INTERNATIONAL JOURNAL OF ENGINEERING … · petroleum hydrocarbon [1]. Power production by MFCs...

INTERNATIONAL JOURNAL OF ENGINEERING TECHNOLOGY AND SCIENCES (IJETS) Vol. 2 (1) DEC 2014

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An overview on biological concept of microbial fuel cells

Ravinder Kumar

Faculty of Engineering Technology, Universiti Malaysia Pahang (UMP),

Lebuhraya Tun Razak, 26300 Gambang, Kuantan, Pahang,

Malaysia

Lakhveer Singh*

Faculty of Engineering Technology, Universiti Malaysia Pahang (UMP),

Lebuhraya Tun Razak, 26300 Gambang, Kuantan, Pahang,

Malaysia

Email: [email protected].

Zularisam A. Wahid

Faculty of Engineering Technology,

Universiti Malaysia Pahang (UMP),

Lebuhraya Tun Razak,

26300 Gambang, Kuantan,

Pahang, Malaysiaya

Abstract—The microorganisms such as bacteria act as biological catalysts in microbial fuel cells (MFCs). These microorganisms oxidize the organic matter at the anode and transfer the electrons exogenously to the electrode surface (anode surface) without any need of artificial mediators. Such microorganisms have been referred as exoelectrogens. They form conductive biofilms on the electrode surface, metabolize the substrates into electrons, protons and carbon dioxide. The exoelectrogens produce some redox proteins such as c-type cytochromes and pili for direct electron transfer, and some electron shuttles e.g., pyocyanin for mediated electron transfer.

Index Terms— Microbial fuel cell (MFC), exoelectrogens; electricity production; c-type cytochromes (c-Cyts); microbial nanowires).

I. INTRODUCTION

Microbial fuel cells (MFCs) have long been

considered an attractive mean for converting various carbohydrate wastes directly into electricity using electrogenic bacterial cells in the anode compartment. Most MFCs have been operated using anaerobic or facultative aerobic bacteria which oxidize various substrates including glucose, sewage sludge and petroleum hydrocarbon [1]. Power production by MFCs varies with bacterial cell species, specific substrate concentration, cathode catalysts and the MFC configuration [2]. Typically, MFCs which were operated with a mixture of bacterial cells produced higher specific power than MFCs operated by a monoculture in the anode compartment [1]. Knowledge and understanding of the anode biofilm components, morphology formation steps and electron transfer mechanism may lead to better biofilm conductivity in MFC. General principle of a MFC is given in Fig.1.

The world got the first glimpse more than a century ago that bacteria could generate electricity in a MFC

with the publication of Potter in 1911. However, it is only recently in last two decades MFC technology is in the limelight of research for bioelectricity production, achieved waxed power outputs. MFC is a promising technology for harvesting energy that can be advantageously combined with various applications, such as bioremediation, sensors and powering electronic monitoring devices. It is because of the emergence of exoelectrogens since they produce such proteins or molecules that can transfer the electrons exogenously directly to the electrode, deploying the use of toxic and expensive artificial electron shuttles in MFCs. Several phylogenetically diverse microbes (mostly bacteria) have been reported to generate electricity in mediatorless MFCs. Five classes of Proteobacteria, Firmicutes and Acidobacteria phyla; some microalgae, yeast and fungi have shown current generation in the technology. The prevalent bacterial species known to produce electricity in MFCs include dissimilatory iron reducing Geobacter spp., Shewanella spp., Rhodoferax ferrireducens, Aeromonas hydrophila, Pseudomonas aeruginosa, Clostridium butyricum and Enterococcus gallinarum. Alternatively, microalgae have been used as a substrate or biocathode in MFC. Microalgae biomass contains high level of proteins (32%) and carbohydrates (51%) which are readily degradable by the exoelectrogens to produce electricity [3]. Velasquez-Orta et al. obtained power density of 277 W/m3 in MFC using Chlorella vulgaris (microalgae) powder as a substrate [4]. However, the electron transfer mechanisms and the proteins or molecules involved are known only in limited exoelectrogens, particularly in Geobacter sulfurreducens and Shewanella oneidensis. G. sulfurreducens, a Gram-negative bacterium can oxidize acetate completely into protons and electrons, and can reduce minerals like Fe (III) oxides effectively. It forms highly thick biofilms (more than 50 µm) on electrode surfaces. In its monolayer biofilms, it transfers the electron to the electrode surface directly through outer membrane c-


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Cyts (the pivotal c-Cyts is OmcZ) or via secreting riboflavin that interacts with c-Cyts to shuttle the electrons out of the cell [5]. In thick multilayer biofilms, G. sulfurreducens produces conductive proteinaceous pili that are made of PilA monomer units, encoded by the gene pilA. Multiple lines of evidence have confirmed the role of pili in electron transfer mechanisms and are also essential in electroactive biofilm formation [6]. Some proteins other than the outer membrane c-Cyts, the outer-membrane multicopper proteins OmpB or OmpC are also required for Fe (III) oxide reduction [6]. The deletion of ompC gene inhibited the reduction of insoluble Fe (III) oxides, indicating its importance in optimal Fe (III) oxides reduction by G. sulfurreducens [7]. The other widely studied exoelectrogen, S. oneidensis can reduce variety of substrates and can transfer the electrons exogenously via outer membrane c-Cyts containing MtrCAB complex [4]. The exoelectrogen secretes two types of flavins i.e. riboflavin and flavin mononucleotide. Both flavins interact with c-Cyts and these flavin- c-Cyts complexes help in hopping the electrons across the membrane [5]. An oxygenic phototrophic cyanobacterium, Synechocystis sp. produces nanowires, has been discovered to generate electricity in MFC. Another exoelectrogen i.e. Aeromonas hydrophila produces nanowires (type IV pili), are essential for electron transfers to the electrodes and biofilm formation.

In this article, the authors endeavor to elucidate the physiological and molecular concepts of microbial mechanisms that are advantageous to the MFC technology. Further, the article reviews the different mechanisms of electron transfer from microorganisms to electrode and vice-versa, followed by the explanation of high current producing microorganisms used for electricity production at anoxic and oxic compartments of MFC.

Fig. 1 Principle of a Microbial Fuel Cell.

II. MICROBIAL METABOLISM

Bacteria live in biofilms to a great degree. Bacterial cells embedded in a complex, self-produced polymeric matrix, attached to biotic or abiotic surfaces, referred as a biofilm. Biofilm can be formed by a single bacterial species (pure culture biofilm) or by multiple bacterial species (mixed culture biofilm). In MFCs, it is highly advantageous to produce electroactive biofilms to generate electricity more efficiently. It’s blatant from the previous studies that the bacteria incompetent to form biofilms on the electrode are unable to generate substantial current densities in MFCs. However, the bacteria competent to form thick biofilms on the anode generate higher current densities in rival to bacteria adept to form thin biofilms. For example, confocal microscopy revealed that Geobacter sulfurreducens forms highly structured and thick multilayer biofilms (>50µm) and Therminocola ferriacetica, a Gram-positive bacteria form thick biofilms (~38 µm), generated a sustained current density 7-8 Am-2 [8]. While, Therminocola potens and Clostridium ljungdahlii form monolayer biofilms, produced comparatively lower current densities [9].

Diverse group of exoelectrogens have been experimented in MFCs for electricity generation, bioremediation and other manifold applications. Besides, sundry nutrients (acetate, glucose, starch, sucrose, ethanol, lactate and xylose etc.) and wastewaters (beer brewery wastewater, chocolate industry wastewater, swine wastewater, paper recycling wastewater and protein-rich wastewater etc.) from various sources have been used as substrate for microbial growth in MFC technology [10]. Despite the availability of wide range of substrates and exoelectrogens, only limited and specific exoelectrogens are known to produce electricity in MFCs. Exoelectrogens from various categories such as Gram-positive bacteria, Gram-negative bacteria, yeast, cyanobacteria, algae and even fungi have already been utilized in different kinds of MFCs. The organisms are substantially efficient for electricity generation that can completely oxidize complex organic substrates into their respective components in the anodic chamber. But, a particular exoelectrogen can oxidize specific substrates or a specific type of substrate for its growth and energy production. Moreover, depending on the type of substrate every exoelectrogen has different pathways and genes, enzymes or proteins for its degradation or oxidation. Therefore, selection of a suitable bacterial consortia and preferred substrate


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determine the output of MFC. For example, a MFC fed with aerobic-anaerobic sludge inoculum and glucose, when operated for three months increased the bacterial substrate to electricity conversion rates by seven fold [11]. It is also important to get an idea about microbial metabolic pathways regulating electrons and protons flow prior to rate the electricity generation in MFC. In MFC, organic substrates containing carbohydrates, lipids and proteins serve as electron donors for redox reactions at the anode to produce energy. These complex organic molecules further undergo through glycolysis and other respective processes to yield acetyl Co-A, which then participate in citric acid cycle (also known as TCA cycle or Kreb’s cycle) (see Fig. 2).

Fig. 2 Reduction of NAD+ and FAD to their electron carrier forms (NADH and FADH2)

through the Citric Acid Cycle (also known as tricarboxylic acid cycle or TCA cycle).

One complete turn of the cycle converts three equivalents of nicotinamide adenine dinucleotide (NAD+) into three equivalents of reduced NADH; one flavin adenosine dinucleotide (FAD) reduces to FADH2 and CO2 is released as by-product. These metabolic pathways (glycolysis and Kreb’s cycle) occur in cytoplasm in both prokaryotes (bacteria) and eukaryotes (yeast). NADH and FADH2 acts as electron carriers, which then transfer their electrons to electron transport chain (ETC) to produce energy carrier molecule, adenosine triphosphate (ATP). In bacteria respiratory reaction occurs in the cell membrane (constituting outer cell membrane, inner cell membrane and periplasm), the machinery containing all the proteins or enzymes required for the electron transfers (the basis of MFC). While in yeast, ETC resides on the inner mitochondrial membrane. The ETC typically contains four intermediary proteins NADH dehydrogenase, ubiquinone, coenzyme Q and

cytochromes (however, these intermediary proteins may vary with species). The electrons are passed through these proteins to the final electron acceptor and the protons (reduced) are pumped out of the cell, in the anode which is then transferred to the cathode through PEM. Prior to the prominence that bacteria can facilitate electron transfer, chemical mediators were utilized to catalyse electron transfer from inside the bacterial cell to the anode surface. These mediators react with ETC components and get reduced, release out of the cell and transfer their electrons to the anode.

III. ELECTRON TRANSFER MECHANISM

In MFCs, the bacterial transfer of electrons from the substrates to electrodes is mainly through three ways (Fig.3). The mechanism of electron transfer may be of short range direct electron transfer (via c-type cytochromes), electron transfer via electron shuttles secreted by exoelectrogens or by long range electron transfer (through pili).

Short range direct electron transfer

Diverse exoelectrogens are known to mediate electrons from inside the cells to electrode surfaces via direct electron transfer mechanism. But, Geobacter sulfurreducens has been studied most extensively to comprehend the mechanisms for direct electron transfer. G. sulfurreducens contains the enzymes for the central metabolism to anaerobically oxidize carbon (effectively acetate) completely to carbon dioxide and water and can transfer electrons to a variety of electron acceptors including metal ions, elemental sulphur and fumarate [12]. Earlier studies revealed that G. sulfurreducens does not use shuttles to reduce the electrodes but utilizes alternative electron transfer pathways; takes electrons generated from central metabolism in the cytoplasm and transfer them by direct contact to extracellular electron acceptors, such as Fe (III) oxides. The genetic studies of G. sulfurreducens genome unveiled the presence of unprecedented number of c-Cyts containing heme groups in their motifs, exposed on the outer surface of cell [7, 13]. The profusion of cytochromes is an advantageous characteristic for the organism that ameliorates electron transport and suggests the flexibility and redundancy in the electron transfer networks which further assists the reduction of diverse metal ions in natural environments. The alternative electron transport components include dehydrogenases,


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quinones, iron-sulfur proteins, and b-type cytochromes. The electron transport proteins reside in the periplasm or on outer membrane of G. sulfurreducens that transport the electrons through the plasma membrane to outside of the cell. Besides, many studies including gene deletions demonstrated that c-Cyts transfer electrons to diverse extracellular electron acceptors in vitro as well as in vivo [61, 62]. Furthermore, the studies of G. sulfurreducens biofilms evinced that OmcZ (outer membrane c-type cytochrome Z) acts as the electrochemical gate between cells adhered on the electrode and the electrode surface, as some of the cytochromes were present in close proximity of electrode surface for direct electron transfer. The immunogold labelling of G. sulfurreducens biofilms validated the accumulation of profuse OmcZ at biofilm and anode interface [7]. Besides, deleting the gene for OmcZ dramatically increases the resistance of electron exchange between the anode and the biofilm. Therefore, all these results confirmed the vital role of OmcZ in direct electron transfers. Multiple lines of evidence suggest that OmcZ is the most important cytochrome in high current producing biofilms, is a octaheme hydrophobic protein occurs in two forms; one large form (OmcZL)with a molecular mass of ca. 50 kDa and a short form (OmcZS) having a molecular mass of ca. 30 kDa [7]. OmcZS is a cleaved product of OmcZL and subcellular-localization studies suggested that OmcZS is the predominant extracellular form of OmcZ. Moreover, redox titration analysis revealed that heme groups in OmcZ cover a large reduction potential range (-420 to -60 mV), with midpoint reduction potential of ca. -220 mV (versus the standard hydrogen electrode) [14]. Cyclic voltammetry of biofilms of wild type and mutant G. sulfurreducens strains grown on graphite cloth anodes acting as electron acceptors with acetate as the electron donor evinced that OmcZ participates in homogeneous electron transfer (through the biofilm bulk) while OmcB mediates heterogeneous electron transfer (across the biofilm/electrode interface) and OmcS plays a secondary role in homogenous electron transfer while OmcE is salient in Fe (III) oxide reduction [15]. Deletion of the gene encoding OmcF, a monoheme outer membrane c-type cytochrome, substantially decreased the current production [66]. Further, the results suggested that OmcF is required for optimal current production, not because OmcF is directly involved in extracellular electron transfer but OmcF is required for the appropriate transcription of other genes that either directly or indirectly is involved in electricity production [16].

Electron transfer via electron shuttles secreted by exoelectrogens

Many exoelectrogens including Gram-positive and Gram-negative bacteria, such as Geothrix fermentans, Shewanella oneidensis, Pseudomonas aeruginosa, Lactococcus lactis secrete soluble electron shuttles to further the electron transfer to electrodes. The first evidence of an organism synthesizing a soluble compound that promotes electrode reduction came with the publication of Bond et al.; suggested that G. fermentans releases a soluble electron shuttle which promotes reduction of Fe (III) oxides [17]. G. fermentans when grown with Fe (III) but, not with fumarate as electron acceptor; secreted two different soluble redox-active electron shuttles with separate redox potentials[70]; first was riboflavin at redox potential of -0.2 V and the other, still unknown at redox potential of 0.3 V. Earlier, P. aeruginosa strain KRP1 isolated from MFC; produced pyocyanin and phenazine-1-carboxamide.

Fig. 3 Different mechanisms of electron transfers (A) Short- range electron transfer by

microorganisms through c-type cytochromes associated with the outer cell membrane. (B)

Electron transfer via soluble electron shuttles. An oxidized shuttle molecule is reduced by the redox-

active proteins at the outer cell surface which further donates its electron to the electrode. (C)

Long-range electron transfer. The electrons from the distant and other cells are transported to the

electrode through conductive biofilm via proteinaceous electrically conductive pili [7].

A mutant strain of P. aeruginosa KRP1, deficient in the synthesis of pyocyanin and phenazine-1-carboxamide, achieved only 5% power output as compared to wild type’s strains [18]. Further, the study demonstrated that pyocyanin promote substantial


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electron transfer, not only used by P. aeruginosa but also by other bacterial species as well.

Long range electron transfer

In monolayer biofilms, most of cells remain in proximity of electrode surface contribute for generation of current densities. Alternatively, in multiple layer biofilms, only few cells can access the electrode surface, then, how the cells in biofilms distant from the electrode surface transfer electrons to the electrode surface; has been discussed in this section. Long-range electron transfer is mediated by dense network of pili with metallic like conductivity produced by the microorganism, responsible for the conductive biofilms of high current production. Though, diverse exoelectrogens are known to produce pili but only Shewanella sp. [19] and Geobacter sp. [20] are competent to produce conductive pili that account for electricity production.

The role of conductive pili in long range electron transfer in biofilms was demonstrated earlier in Geobacter sulfurreducens, and the study revealed that these electronic networks contributed for more than 10-fold increase in electricity production [21]. G. sulfurreducens pili are type IV pili composed by the monomers of PilA protein and are similar to that of other type IV pili [20,5]. Type IV pili are small structural proteins of molecular weight ca. 7 to 20 kDa, 10-20 µm long and 3-5 µm broad with a conserved N-terminal domain forming α-helix with a transmembrane domain and a protein-protein interaction domain that allows monomers to interact with each other to generate a hydrophobic filament core [22]. Moreover, C terminus of PilA contains a conserved sequence of aromatic amino acids (Trp, Phe, Tyr, His, and Met) responsible for overlapping of pi-pi orbitals in the pili structure and consequently for metal like conductivity; lacks in non-conductive biofilms [23]. The function of PilA is directly regulated by PilR which functions as an RpoN-dependent enhancer binding protein. Further, the study revealed that a strain deficient in pilR gene showed waned insoluble Fe (III) reduction as well as soluble Fe (III) reduction [24]. G. sulfurreducens strain Aro-5 was demonstrated for substitution of alanine amino acid for each of the five aromatic amino acids in C-terminus with a graphite anode serving as the electron acceptor for Fe (III) reduction. The strain expressed pili with multiheme c-Cyts OmcS, was incompetent for extracellular electron transfer and Fe (III) reduction and consequently showed extensively diminished

conductivity in rival to wild type strain [25]. Reguera et al. demonstrated, pilA -deficient mutant of G. sulfurreducens was incompetent to reduce Fe (III) oxides, indicating that pili of G. sulfurreducens are pivotal for Fe (III) oxide reduction. Further, atomic force microscopy revealed that the pili were highly conductive, transferring electrons from the cell surface to the surface of Fe (III) oxides and hence, serves as microbial nanowires [26]. The hypothesis that cytochromes are associated with G. sulfurreducens pili and serve a key role in electron transfer along with pili was ruled out with the publication of Malvankar et al. [27, 20]; the study unveiled that conductivity of G. sulfurreducens nanowires don’t attribute to cytochromes because the spacing between cytochrome-to-cytochrome was ca. 200 times greater than required for electron hopping. It was further clarified by Liu et al., demonstrated a G. sulfurreducens strain PA, pilA gene was replaced with pilA gene of Pseudomonas aeruginosa PAO1, expressed the pili subunits and c-type cytochrome OmcS similar to control strain.. Further, the results suggested that c-type cytochrome OmcS on pili don’t confer for the conductivity of pili [28].

The exoelectrogen studied for ‘microbial nanowires’ so far beyond Geobacteraece family is Shewanella oneidensis. Naggar et al. by using conducting probe atomic force microscopy technique provided the evidence that S. oneidensis MR-1 nanowires are conductive in nature. Further, the study demonstrated that mutants deficient in genes for c-type decaheme cytochromes MtrC and OmcA produced nonconductive nanowires [29]. Electronic transport characteristics of S. oneidensis MR-1 nanowires was further studied and exhibited p-type, tunable electronic behaviour with a field-effect mobility [30]. A multistep hopping mechanism has been proposed for extracellular charge transfer in S. oneidensis MR-1 biofilms, suggesting that redox components are associated with each other at less than 1 nm distance forming a chain along extracellular appendages, responsible for electron hopping or electron tunnelling [29,31]. However, the actual organization of cytochromes on S. oneidensis MR-1 nanowires and their exact role in electron transfer mechanism is yet to be clarified.

Direct interspecies electron transfer

It is quite evident from the earlier genetic and transcriptomic studies that during the syntrophic growth, G. metallireducens and G.


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Role of Bio-filtration in Petrochemical Wastewater treatment using CSTR

Md. Nurul Islam SIddique

Faculty of Engineering Technology

University Malaysia Pahang

Kuantan, Malaysia

[email protected]

A.W. Zularisam*

Faculty of Engineering Technology

University Malaysia Pahang

Kuantan, Malaysia

[email protected]

Abstract— Continuous stirred tank reactors (CSTR) operated at 35"C, were efficaciously used for the anaerobic digestion of a petrochemical effluent. Bio-filtration of petrochemical wastewater was carried out and the results were evaluated in terms of basic water quality parameters. The effects of organic loadings, solid retention time were also investigated. COD reductions of 93-98% were found at an optimum retention time of 2.3 days and a loading rate of 4.7 kg COD/m3/d. The amount of biogas produced was 0.88 m3/m3/d (STP) with a methane content of 90-96%. Volatile fatty acid removal was also achieved up to 97% after performing bio-filtration process. Therefore, the current work revils that bio-filtration of petrochemical wastewater using CSTR might be an effective solution to the prevailing treatment limitation.

Index Terms—Anaerobic digestion, Petrochemical wastewater, CSTR, Methane

I. INTRODUCTION

In today's industrial civilization, it has become increasingly important to prevent the pollution of our limited water resources by providing adequate treatment of effluents from industrial sources [1]. Anaerobic waste treatment is one of the major biological waste treatment processes in use, and has been employed for many years in municipal sewage treatment units [2]. The search for greater efficiency and better economy as well as the interest in methane as a renewable energy source, has led to the study of new types of anaerobic reactors [3]. In recent years considerable attention has been focused on a new range of reactors for the treatment of high strength industrial waste water [4]. One of the most successful of this range is the continuous stirred tank reactors [5]. The continuous stirred tank reactor (CSTR) is equivalent to a closed-tank digester equipped with mixture facility [6]. Over and above basic reactor design, the filling of most anaerobic digesters are mixed to assure competent transfer of organic material

for the active microbial biomass, to discharge gas bubbles trapped in the medium and to prevent sedimentation of denser particulate material [7].

In Malaysia a unique high strength petrochemical effluent is produced by the crude petroleum refining process. This high strength effluent contains approximately 93-95 g/L volatile fatty acids. Large amounts of these fatty acids are produced per annum and have to be disposed of by other means. This paper reports on the use of continuous stirred tank reactors for the anaerobic treatment of high strength petrochemical effluent.

II. MATERIALS AND METHODS

a) Sample collection and characterization

A100 L of PWW sample was collected in plastic containers at the point of discharge in to the main stream and from the receiving stream. Then, transported to the laboratory and preserved at 4˚C for further study were physicochemical analysis and treatment. Effluent pH was maintained at 6.5, using 5N NaOH solution. Alkalinity was maintained between 1400-1800 mg CaCO3/l by NaHCO3. Complementary nutrients like nitrogen (NH4Cl) and phosphorous (KH2PO4) were employed to maintain a COD: N: P ratio of 250:5:1. Table1 explains composition and characteristics of PWW. With a view to eliminate trash materials, the prepared sludge was initially passed through a screen.

Table 1 Composition and Characteristics of PWW

Parameters CPW

pH 6.5-8.5

BOD 8-32

COD 15-60

TOC 6-9

Total solids 0.02-0.30


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Acetic acid 46.60

Phenol 0.36

Total Nitrogen 0.05-0.212

Total Phosphate 0.102-0.227

Volatile fatty acids 93-95

*Except pH and Acetic acid, all parameters in gL-1

CSTR Construction and Operation.

Details of the continuous stirred tank reactor (CSTR) are given in Figure 1. The reactors consisted of 1 m glass columns, each with a working volume of 3.5 liter. The operational temperature was 35°C [8]. Inside each reactor an inert cylindrical, polyethylene bacterial carrier was placed. The surface area of the support material was 3,500 cm2. The substrate was continuously pumped in at the top of the reactor at the required rate while the reactor effluent was removed from the bottom. The reactor liquid level volume was electronically controlled [9]. Gas exited at the top of the reactor and volumes were determined by a means of a brine displacement system. At the start-up, the reactors were filled with sludge from a local municipal plant and slowly fed with a diluted fatty acid solution, which corresponded to the fatty acid composition of the factory effluent. With the start of gas production, the dilution was gradually reduced until the fatty acid solution corresponded to 50% of the effluent fatty acid concentration. Approximately 8 weeks were required, at a hydraulic retention time of 4.0 days, to obtain a 90% COD removal.

Analytical Methods

The COD was measured by direct digestion method, using HACH apparatus LR (3–150 COD), HR (20–1500 mg/L COD), and HR plus (20–15,000 mg/L COD and above). Total organic carbon was measured by direct method of low, medium, and high range tests (N tube reagent set), using HACH DBR 200 TOC program in HACH apparatus. Day-to-day gas yield was determined, by a revocable device, having liquid displacement technology. Biogas configuration was determined by a Perkin Elmer gas chromatograph having a thermal conductivity detector. A GC column packed with supelco 100/120 mesh was employed to distinct CH4 and CO2. Helium was employed as carrier gas maintaining flow rate 30 mL/ min. The columns sustained at 50˚C. Volatile fatty acids (VFAs) were analyzed using that similar GC, having a flame

ionization detector connected to a supelco capillary column. Helium was employed as carrier gas maintaining flow rate 50 mL/ min. Injector and detector temperatures were 200 and 220˚C, individually. The kiln temperature was fixed at 150˚C for 3 min and subsequently amplified to 175˚C. The recognition limit for VFA investigation was 5.0 mg/L [10].

Statistical Analysis

Data analysis was performed with Microsoft EXCEL 2010. Regression coefficient (R2) was calculated to analyze the effect of OLR on COD removal efficiency, biogas, and methane.

Figure 1: CSTR experimental setup

III. RESULT AND DISCUSSION

Chemical Oxygen Demand, Hydraulic retention time, Organic loading rate and Methane

After adjusting the pH of the petrochemical effluent, a red-brown precipitate formed. This was ascribed to the precipitation of iron and other trace metals. With continuous agitation on a magnetic stirrer this was used as substrate to feed a preconditioned reactor. The proficiency of this reactor was found to deteriorate with time and stabilized at a COD reduction of approximately 39% (Table 2). This low performance was ascribed to the precipitation of the minerals which possibly caused a growth limitation for the microbial population. A second reactor was fed with effluent that had been filtered through a Whatman no. 1 filter to remove the precipitate and to which a mineral solution had been added, to prevent any growth limitations to the microbial population. This reactor operated satisfactorily and for a period of 120 days a COD reduction of more than 98% was found (Table 2). These results show that the petrochemical effluent can be effectively treated by the anaerobic digestion process using a continuous stirred tank reactor


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(CSTR). The data, shown in Table 2, was obtained at the hydraulic retention time (HRT) with the highest

COD reduction. With the shortening of the HRT beyond this point a sharp decrease in COD reduction and corresponding increase in volatile fatty acids, especially propionic acid, was found. Thus the HRT with the highest COD reduction was considered as the optimum for the system under the described conditions. It is possible that with a bigger microbial surface area or different film supports, shorter HRT's could be obtained as shown by Movahedyan et al (2007)[11]. The results also showed that the microbial population, especially the methanogens, was successfully retained on the support material. The reactor effluent COD was found to consist of mainly soluble COD with the difference in soluble and total COD being less than 2.0%. The methane content of the gas produced by this type of reactor was very high compared with the results of others [12]. The collected gas contained approximately 90-96% methane. Since the petrochemical effluent was initially neutralized, the fatty acids were thus in the salt form. During the digestion process the acetate ions are assimilated by the microbial population and the sodium ions are set free into the surrounding medium where sodium hydroxide is regenerated. The pH of the reactor effluent was found to be around 7.1. This could be the result of the regenerated sodium hydroxide. The carbon dioxide formed in the reactor, and not used by the methanogens, will react to form sodium carbonate [13]. The excess carbon dioxide is thus removed from the reactor and mostly only methane is set free explaining the high methane to carbon dioxide ratio [14]. That’s how this experiment reviles a clear concept of producing much more biogas with the help of co-digestion technology. However, bio-filtration with continuous stirred tank reactor (CSTR) appears to be effective treating petrochemical wastewater.

Table 2: CSTR performance via filtration

Parameter Effluent

Unfiltered Filtered

Hydraulic retention time (days)

4 2

Loading rate (kg COD/m3/d)

3.17 4.7

COD removal (%) 39 98

Biogas production rate (m3/m3/d)

0.13 0.90

Methane content (%) 57% 92%

Volatile fatty acid removal (%)

40% 97%

pH reactor effluent 6±0.3 7.1±0.2

B. Petroleum Hydrocarbon, Microbial cell production & MLSS:

Fig 2 explains that total petroleum hydrocarbon concentration was gradually decreased with the increase of SRT. Under these testing conditions, the MLSS Values. Moreover, as SRT values exceed beyond 10 days, relatively small incremental changes formed for both petroleum hydrocarbons and MLSS concentrations. During AD, it is a must to measure the quantity of sludge produced per day due to its effect on process stability and disposal facilities. In order to prevent excess accumulation of microbial cell in the system, the quantity of sludge produced/ day must be wasted [15-16]. As AD incorporates cell recycle, the additional importance of cell decay and sludge production at increasing SRT can be seen by examining SRT with respect to MLSS and microbial cell production, as illustrated by Fig. 3. This plot illustrates the net synthesis in the system broadly, the mass of cells formed less those lost by decay. The highest daily production of 110 g/d was found at 3 d SRT. It reflects the necessary time frame and accumulative production at which a great deal of the dissolved petroleum substrate has been degraded and transformed to cells while decay is not yet a major factor . Nevertheless, sludge production started to turn down steadily through the remaining SRT values with the extended SRT values. A shift from cell synthesis to cell decay due to the increasing SRT values and the attainment of complete stabilization of the petroleum hydrocarbons might be suggested by the declination of the curve. The regression values (R2) of fig 2 and 3 were determined 0.96 and 0.97 which implies that the results have obvious consistency.

Figure 2: Effluent petroleum concentration vs. solid retention time for co-digestion process


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Figure 3: Effluent microbial cell concentration vs. solid retention time for co-digestion process.

IV. CONCLUSION

1. The results show that effluent from a petrochemical industry is amendable to treatment by an anaerobic digestion process. The HRT's could probably be shortened by the increase in microbial surface area.

2. The precipitation of iron and trace metals caused a growth limitation for the microbial population. This limitation could be removed by filtering the effluent and adding a mineral solution.

3. The methane content was high (90-96%) due to the self-scrubbing effect of this type of reactor.

V. ACKNOWLEDGMENT

The authors would like to thank faculty of civil engineering and earth resources, university Malaysia Pahang, for providing continuous laboratory facility. The present research was made possible availing facility provided by RDU-0903113.

VI. REFERENCES

[1] M.N.I. Siddique, M.S.A. Muniam, and A. W. Zularisam, “Mesophilic and thermophilic biomethane production by co-digesting pretreated petrochemical wastewater with beef and dairy cattle manure”, J. Ind. Eng. chem, vol. 20, pp. 331-337, 2014.

[2] M.N.I. Siddique, M.S.A. Muniam, and A. W. Zularisam, “Feasibility analysis of anaerobic co-digestion of activated manure and petrochemical wastewater in Kuantan (Malaysia)”, J. Clean. Prod, doi:10.1016/j.jclepro.2014.08.003, 2014.

[3] M.N.I. Siddique, M.S.A. Muniam, and A. W. Zularisam, “Role of biogas recirculation in enhancing petrochemical wastewater treatment efficiency of

continuous stirred tank reactor”, J. Clean. Prod, doi:10.1016/j.jclepro.2014.12.036, 2014.

[4] M.N.I. Siddique, M.S.A. Muniam, and A. W. Zularisam, “Influence of flow rate variation on bio-energy generation during anaerobic co-digestion”, J. Ind. Eng. chem, doi:10.1016/j.jiec.2014.12.017, 2014.

[5] K. Wang, J. Yin, D. Shen, and N. Li, “Anaerobic digestion of food waste for volatile fatty acids (VFAs) production with different types of inoculum: Effect of pH”, Bioresource Technol., vol. 161, pp. 395-401, June 2014.

[6] L. Alibardi, R. Cossu, M. Saleem, and A. Spagni, “Development and permeability of a dynamic membrane for anaerobic wastewater treatment”, Bioresource Technol., vol. 161, pp 236-244, June 2014.

[7] J. Zhao, X. Ge, J. Vasco-Correa, and Y. Li, “Fungal pretreatment of unsterilized yard trimmings for enhanced methane production by solid-state anaerobic digestion”, Bioresource Technol., vol. 158, pp. 248-252, April 2014.

[8] W. Choorit, and P. Wisarnwan, “Effect of temperature on the anaerobic digestion of palm oil mill effluent”, E. J. Biotechnol, vol.10, pp. 376–385, 2007.

[9] B.E. Rittmann, and P.L. McCarty, “Environmental biotechnology: Principles an applications” New York: McGraw-Hill Book Co., 2001, 768. ISBN 0–072-34553–5.

[10] APHA. Standard methods for the examination of water and wastewater. 19 th ed. Washington, DC: American Public Health Associayion, 2005.

[11] H. Movahedyan, A. Assadi, and A. Parvaresh, “Performance evaluation of an anaerobic baffled reactor treating wheat flour starch industry wastewater” Iran J. Environ. Health. Sci. Eng., vol. 4, pp. 77–84, 2007.

[12] S. Michaud, N. Bernet, P. Buffiere, M. Roustan, and R. Moletta, “Methane yield as a monitoring parameter for the start-up of anaerobic fixed film reactors” Wat. Rese., vol. 36, pp.1385–1391, 2002.

[13] B. Rincon, F. Raposo, R. Borja, J.M. Gonzalez, M.C. Portillo, and C.J. Saiz-Jimenez, “Performance and microbial communities of a continuous stirred tank anaerobic reactor treating twophases olive mill solid wastes at low organic loading rates” Biotechnol., vol. 121, pp. 534–543, 2006.

[14] P.J. Sallis, and S. Uyanik, “Granule development in a spilt-feed anaerobic baffled reactor” J. Biores. Technol., vol. 89, pp. 255–265, 2003.

[15] S. Kalyuzhnyi, L. Santos, and J.R. Martinez, “Anaerobic treatment of raw and preclarified potato-maize wastewater in a UASB reactor” J. Biores. Technol. Vol. 66, pp. 195–199, 1998.

[16] R. Grover, S.S. Marwaha, and J.F. Kennedy, “Studies on the use of an anaerobic baffled reactor for the continuous anaerobic digestion of pulp and paper mill black liquors” J. Process Biochem, vol. 39, pp. 653–657, 1999.


13

Various Techniques Involved in Acquisition of Image Using Image Sensors

J Rama Tulasi

Assistant Professor

Malla Reddy Institute of Engineering and Technology

Maisammaguda ,Secunderabad

Sai Preetham Sata

B-Tech (Mechatronics)

SRM University,Chennai,Tamil Nadu

[email protected]

Sata Venkata Yesoda Bhavana

B-Tech

Electronics and Instrumentation

SASTRA University, Tamil Nadu

Abstract— Image sensors are being used predominantly in almost every aspect of science and technology. When an image is captured by a network camera, light passes through the lens and falls on the image sensor. This image is converted to voltage and it is further converted to digital format that act as input signal for the PC host. The image acquisition is done using single sensor, in-line arrangement of sensors in the form of a sensor strips or in the form of a 2-D array of individual sensors. The following paper deals with the various techniques involved in the design of the image sensors and few methods are being discussed to overcome the demerits in the above sensors.

I. INTRODUCTION

Image sensors are overwhelmingly used in the field

of astronomy and defense applications and automation

industries. These are basically used to acquire the

image in the form of analog voltage. The amount of

voltage that is produced is dependent on the light

intensity acquired by the sensor. The light intensity

acquired by the sensor is generated by the combination

of an “illumination” source and the reflection or

absorption of energy from that source by the elements

of the “scene” being imaged. For example, the

illumination may originate from a source of

electromagnetic energy such as radar, infrared, or X-

ray energy. The light energy is transformed into a

voltage by the combination of input electrical power

and sensor material that is responsive to the particular

type of energy being detected. The output voltage

waveform is the response of the sensors, and a digital

quantity is obtained from each sensor by digitizing its

response. The image acquisition is done using single

sensor, in-line arrangement of sensors in the form of a

sensor strips or in the form of a 2-D array of individual

sensors. Single point laser scanner, computer

radiography, photodiode are some of the examples of

image sensors using single sensor. Flatbed scanner,

film scanner .These type of sensors also acts as basis

for medical and industrial computerized axial

tomography (CAT) imaging. Charge coupled device

(CCD) sensors; CMOS (Complementary Metal-oxide

Semiconductor) image sensors are examples of the

sensors that use an array of individual sensors to

acquire the image. Microwave image is one of the

imaging techniques that are used to detect the hidden

objects using electromagnetic radiation in the

frequency range of microwaves. RADARS and

LIDAR are some of the examples of microwave

imaging. Thermal imaging also utilizes

electromagnetic radiation but the frequency range

varies in infra-red(IR) region .Digital still cameras,

machine vision, security and surveillance, video

conferencing and camcorders, mobile phones,

document scanning, medical imaging, PC cameras,

barcode readers, scientific imaging, aerospace and

defense , automotive, toys and games, biometrics are

some of the applications where image sensors are

being used profoundly. Due to the growth in demand

for cameras, camcorders, multimedia mobile phones,

and security cameras, the image sensors’ market is

experiencing significant growth. Due to advances in

technology, high definition image sensors with

increased resolution are being developed.

II. IMAGE ACQUISITION USING A SINGLE

SENSOR

The most common sensor of this type is the photodiode, which is constructed of silicon materials and whose output voltage waveform is proportional to light. The usage of a filter in front of a sensor improves selectivity. For example, a green (pass) filter in front of a light sensor favors light in the green band


14

of the color spectrum. As a consequence, the sensor output will be stronger for green light than for other components in the visible spectrum.

In order to generate a 2-D image using a single sensor, relative displacements should be present in both the x- and y-directions, between the sensor and the area to be imaged. This arrangement is similar to the one used in high precision scanning, where a negative film is mounted onto a drum whose mechanical rotation provides displacement in one dimension. The single sensor is mounted on a lead screw that provides motion in the perpendicular direction. Since mechanical motion can be controlled with high precision, this method is an inexpensive way to obtain high-resolution images. Other similar mechanical arrangements use a flat bed, with the sensor moving in two linear directions. These types of mechanical digitizers are also referred to as microdensitometers. Another example of imaging with a single sensor includes placing a laser source coincident with the sensor. Moving mirrors are used to control the outgoing beam in a scanning pattern and to direct the reflected laser signal onto the sensor.

Fig 1 Single Point Laser Scanner

Digital images are often corrupted with noise and various other artifacts which significantly degrade the image quality and make the techniques involved in the processing of image complex. Some of the defects that arise in the single sensor imaging are image noise, coloration, demosaicking artifacts, exposure shifts and compression artefacts.

III. IMAGE ACQUISITION USING SENSOR

STRIPS

It consists of an arrangement of sensors in one line to form a sensor strip. The strip provides imaging elements in one direction. Motion perpendicular to the strip provides imaging in the other direction .This type of arrangement is used in most flat bed scanners. Air

borne imaging applications are the most common applications where we find these sensors to be of a significant role. In these applications, imaging system is mounted on an aircraft that flies at a constant altitude and sped over the geographical area to be imaged .The imaging strip that responds to the electromagnetic spectrum is mounted in the direction perpendicular to direction of motion of flight. The imaging strip gives one line of an image at a time, and the perpendicular motion of the strip completes the other dimension.

Fig 2 : Image capture by sensor strip

Computer converts the data into square array and thus the image is acquired.

IV. IMAGE ACQUISITION USING AN ARRAY

OF SENSORS

Sensors are arranged in the form of arrays called pixels and light energy is focused on the pixels and converted into analog voltage .This analog voltage is converted into digital format by an ADC Converter and fed to the PC Host. Some of the sensors which use this technique are Charge coupled device (CCD) sensors and CMOS (Complementary Metal Oxide semiconductor) image sensors. In CCD image sensor, the light (charge) that falls on the pixels of the sensor is transferred from the chip through one output node, or only a few output nodes. The charges are converted to voltage levels, buffered, and sent out as an analog signal. This signal is then amplified and converted to numbers using an A/D-converter. Better light sensitivity, low sensor complexity, moderate to fast speed, high fill factor, electron pixel signal and less noise are some of the characteristics of CCD. Higher power consumption and complex analog circuitry pose barriers to the usage of CCD image sensors.

The complementary metal-oxide semiconductor (CMOS) sensor consists of millions of pixel sensors, each of which includes a photodetector. As light enters


15

the camera through the lens, it strikes the CMOS sensor, which causes each photodetector to accumulate an electric charge based on the amount of light that strikes it. The digital camera then converts the charge to pixels that make up the photo. CMOS chips have several advantages. Unlike the CCD sensor, the CMOS chip incorporates amplifiers and A/D-converters, which lowers the cost for cameras since it contains all the logics needed to produce an image. It is possible to read individual pixels from a CMOS sensor, which allows ‘windowing’, a phenomenon where parts of the sensor area can be read out, instead of the entire sensor area at once. In this way, a higher frame rate can be delivered from a limited part of the sensor, and digital PTZ (pan/tilt/zoom) functions can be used. CMOS sensors are used significantly for the low end applications such as mobile phones. Low sensitivity, low fill factor are some of the demerits possessed by the CMOS sensors. CCD image sensors are more expensive to produce because they are manufactured using a more specialized manufacturing process. According to statistics, it takes approximately 18 months to develop a new CMOS chip, whereas it takes about eight months to develop a simple CCD chip.

Fig 3: CCD Sense Element (Pixel) Structure

Effect Of Electronic Shutter Voltage On Charge Transfer In Ccd Image Sensor

An image is captured by converting the light from an object into an electronic signal at the photosensitive area (photodiode) of a solid−state CCD or CMOS image sensor. The amount of signal generated by the image sensor depends on the amount of light that falls on the image, in terms of both intensity and duration. Therefore, like conventional film cameras, digital cameras require some form of shutter to control exposure. This is generally achieved either by incorporating an external mechanical shutter in front of the image sensor or by an on−chip electronic shutter. When an electronic shutter operation is performed the voltage is shifted to second level. An image sensor such as interline charge coupled sensor

can be damaged when the pixel is exposed to bright light during the shutter operation. The damage is caused by the bipolar junction transistor formed within the sensor. An n-type vertical CCD channel becomes the emitter of the transistor formed, the grounded p-well forms the base and the n-type substrate forms the

Fig: 4 Terminals of Transistor within a sensor

collector. At the centre of the pixel, p-well resistance is very large .The generation of photocurrent on exposure with light is faster than the time required to drain it away. When a bright light falls on the pixel, it shorts the electron shutter voltage and turns on the transistor. This high voltage on vertical CCD induces charge on vertical dielectric which causes increase in dark current in the vertical CCD. With the continued exposure of the bright light it also induces charge in the gate dielectric that results in poor charge transfer and image lag.

Recent Technologies Developed To Improve The Photosensitivity And Reduce Shutter Voltage For A Ccd Sensor

Charge-Coupled Device (CCD) image sensors with a smaller chip and higher photo-sensitivity are in high demand in the consumer market for compact digital still cameras. Reducing the pixel size causes the drop in photosensitivity and increase in shutter voltage. To increase photo-sensitivity, scientists have developed an incident light anti-reflective film technology and a shallow surface p -layer technology. To reduce VOD shutter voltage, development of an epitaxial grown substrate with double impurity concentration layers with optimal impurity concentrations and thicknesses has taken place.

On the conventional structure, the SiO2 insulator film is formed on the surface of the photodiode. This type of structure reflects 20–30% of the incident light at the silicon surface because of the refractive index difference between the SiO2 and Si. In the new structure, a Si3N4 film sandwiched by SiO2 is


16

formed on the surface of the PD to act as an anti-reflective film .The reflectivity property depends on the variability in thickness of SiO2 and Si3N4.The results show that, with thickness of SiO2 as a parameter, the suppressing ability of incident light reflection is more, compared to the results obtained by taking Si3N4 thickness as a parameter.

The results show that smear-noise was strongly affected by the impurity concentration profile at the silicon surface, apparently due to the charge diffusion from the PD to V-CCD, through the lower impurity concentration layer at the silicon surface. The optimal impurity profile design of the p -layer is clearly effective in reducing smear-noise. To reduce shutter voltage, it is necessary to suppress the growth of the depletion layer because suppressing the growth of the depletion layer results in the substrate voltage controlling the potential barrier in the p-well effectively.

It is observed that by using an epitaxially grown substrate with double impurity concentration layers and optimizing the impurity concentration and thickness of the epitaxial layers, the VOD shutter voltage could be decreased linearly by logarithmically decreasing the thickness of the top epitaxial layer.

Recovery of Poor Responsitivity From Uv Radiation In A Ccd Sensor

CCD often shows poor response towards incident UV radiation. The low responsivity is because of the small penetration depth of UV in silicon. Two different approaches to improve this limitation are: structural modifications to the CCD and post-processing of deposited phosphor coatings. Structural designs such as back-side thinned devices and pinned photodiodes exhibit good characteristics but require complicated fabrication processes that may be expensive to manufacture. Organic phosphor coatings to convert UV into visible radiation have been developed as a simpler, yet effective solution. Even though organic coatings exhibit good initial response, they photodegrade to zero efficiency exponentially. To cross this barrier caused by organic coating, inorganic coatings offer a suitable solution due to their unique characteristics.

The important parameters that should be considered to employ this coating are photostability, conversion efficiency, decay time, absorption and emission peak, particle size and distribution and film

morphology. The selected phosphor should have conversion efficiency as close to 100% as possible. This is of particular importance because the luminescence mechanism is isotropic and 50% of the fluorescence is emitted away from the sensor. A fraction of this fluorescence will experience total internal reflection at the film–air interface and will be directed back toward the sensor. This fraction will improve the conversion efficiency.

CONFIGURATION OF IMAGE SENSORS

Image sensors can be configured in one of the following ways:

1) by mounting the sensor on the PC.

2) By creating a hybrid Package where the image sensor is integrated into the systems that also incorporate other sensors.

3) As an integrated circuit with microprocessor.

4) By putting the image sensor and smart electronics on a single chip.

The type of configuration can vary from application to application but the most common trend is to use a sensor IC with an integrated microprocessor. The most important functional features for an image sensor system are accuracy, reliability, image sharpness, performance under low-light conditions, easy download, transfer and replication of images, and long life.

V. CONCLUSION

Suitable image sensors are used for the acquisition of image based on complexity of application. For example, low end devices CMOS Image sensors are being used for the applications where high sensitivity is required.CCD Sensors are being used due to the technological advances that are being stimulated in recent years. Few parameters such as resolution, sensitivity, conversion efficiency etc are being improved. Latest cameras such as HDTV Cameras, Megapixel cameras are emerging in response of these technological advances.

VI. REFERENCES

[1] Ichiro Murakami, Takashi Nakano "Technologies to Improve Photo-Sensitivity and Reduce VOD Shutter


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Voltage for CCD Image Sensors" IEEE Trans on Electron Devices, VOL. 47, NO. 8, August 2000

[2] Akihito Tanabe, Yoshiharu Kudoh , Yukiya Kawakami " Dynamic Range Improvement by Narrow-Channel Effect Suppression and Smear Reduction Technologies in Small Pixel IT-CCD Image Sensors" IEEE Trans On Electron Devices, VOL. 47, NO. 9, September 2000

[3] "single sensor imaging methods and applications for digital cameras" edited by Rastislav Lukac.

[4] "Image sensors in industrial applications" by Smithers apex

[5] "CMOS Image sensors " Abbas El Gamal and Helmy Eltoukhy .

[6] Wendy A. R. Franks, Martin J. Kiik," UV-Responsive CCD Image Sensors With Enhanced Inorganic Phosphor Coatings"

[7] IEEE Trans on Electron Devices, VOL. 50, NO. 2, February 2003.


18

A Review on the Performance of a Vibration Absorber in an Active Suspension System

G.Hima Bindu

Asst. Professor, Department of Mechanical Engineering

MLR Institute of Technology, Dundigal, India

[email protected]

Dr.A.Siva kumar

Professor & HOD, Department of Mechanical Engineering

MLR Institute of Technology, Dundigal, India

Abstract— Active suspension system is to isolate a vehicle body from road irregularities to maximize passenger ride comfort and retain continuous road wheel contact in order to provide road holding with the help of roll and pitch as well as torsion modes. In advance active suspension concepts, damped vibration absorbers, may be fitted to the axles to control wheel hop oscillations. The optimal turning and damping ratio for the vibration absorber to minimize wheel bounce on a random road are computed for a linear two-degree-of freedom system as function of the relative tyre damping rate and mass ratio. The adaptive suspension controllers provide superior passengers comfort over the whole range of road condition. In this connection an attempt is made to explain in detail about suspension system, springs, vibrations and results obtained of different researchers in their experimental investigation.

Keywords— Active Suspension; spring; Vibrations and Quarter car model.

I. INTRODUCTION

Shock absorber or a suspension damping system is a

device for reducing the effect of a sudden shock by the dissipation of the shock's energy. On an automobile, springs and shock absorbers are mounted between the wheels and the frame. When the wheels hit a hole or a raised spot on a road, the springs absorb the resultant shock by expanding and contracting. To prevent the springs from shaking the frame excessively, their motion is restrained by shock absorbers, which are also known by the more descriptive term dampers. The type of shock absorber found on automobiles is usually a hydraulic type that has a casing consisting of two tubes, one telescoping into the other. On some automobiles a type of hydraulic suspension is used to function both as a spring and as a shock absorber. It comprises a sealed spherical container filled with equal volumes of hydraulic fluid and gas under pressure. The compression of the gas, which absorbs the shock, is supplied by the vehicle's engine.

II. REVIEW ON SUSPENSION SYSTEM

a) literature review

The review of literature is discussed to focus on an active suspension system in a passenger car. The analysis of leaf spring and vibrations of the suspension system is discussed in the following sessions.

Rahul N. Sandage et.al [1] has investigated about the ride comfort of the passengers by studying the performance of suspension system. For this a quarter car model with two degree of freedom has been used for checking the performance of semi-active suspension system. To improve ride comfort many analytical and experimental studies on semi-active suspension have been performed at the same time Fuzzy-PID controller work better than the PID controller having fixed gain parameters have been studied. Yahaya Md. Sam et.al [2] studied about the new strategy by which the active suspension system can be controlled. The strategy utilized the proportional-integral sliding mode control scheme. the study is been carried on a quarter-car model and the performance of the controller is compared to the linear quadratic regulator and with the existing passive suspension system. A simulation study is performed to prove the e7ectiveness and robustness of the control approach. Ayman A. Aly et.al [3] has studied why semi-active and active systems are being developed. This study states that due to increased competition on the automotive market has forced companies to research alternative strategies to classical passive suspension systems. To simulate the actions of an active vehicle suspension system a quarter-car 2 degree-of-freedom (DOF) system is designed and constructed on the basis of the concept of a four-wheel independent suspension. The main aim of this study is to illustrate the application of intelligent technique to the control of a continuously damping automotive suspension system. Zhang Jin-qius et.al [4] have investigated how the considerable energy is been wasted in the form of heat due to mechanical


19

vibrations of a conventional vehicle suspension. In recent years for the improvement of vibration attenuating performance as well as the reduction of energy dissipation the regenerative suspensions have attracted much attention. In this investigation the amount of energy dissipation and the potential of energy regeneration are discussed, then the research and development of regenerative suspension is reviewed, and the energy harvesting schemes and their characteristics are summarized and remarked. A. Aldair et.al [5] have studied how to reduce the road roughness in order to give comfort to the passengers and at the same time increase the ride handling associated with the pitching and rolling movements which can be done by designing a robust controller for a vehicle suspension system. This necessitates a very fast and accurate controller to meet as much control objectives, as possible. In this study to design a robust controller to meet the control objective an artificial intelligence Neuro-Fuzzy (NF) technique is been used. The vibrations on each corner of vehicle is been minimized by the proposed controller supplying control forces to suspension system when travelling on rough road. The other purpose for using the NF controller for vehicle model is to reduce the body inclinations that are made during intensive manoeuvres including braking and cornering. A full vehicle nonlinear active suspension system is introduced and tested. Suleiman Abu-Ein et.al [6] have developed a control system and the implementation technology of the controllers and the subsequent experimental study are used for suspension system in automobiles. This development is been done for safe, and driving pleasure, and keeping vehicle occupants comfortable and reasonably well isolated from road noise, bumps, and vibrations. In this study it is been found that active suspension system improves ride comfort even at resonant frequency by the simulation and analytical methodologies which is used to analyze the suspension system. For step input of 0.08 m, the sprung mass displacement has been reduced by 25 % which shows the improvement in ride comfort and sprung mass acceleration reduced by 89. 93% .The suspension travel has been reduced by 74.64% and tire deflection has reduced by 89.73%. Sheilza Jain et.al [7] has studied that the suspension system is designed, where a ¼ model of bus is used to simplify the problem to a one dimensional mass spring-damper system. In this study the open-loop performance on the basis of time response is observed which depicts that the bus suspension has oscillations with large settling time. To overcome this problem, closed-loop system is used. Despite continuous advancement in control theory, Proportional

–Integral (PI) and Proportional-Integral Derivative (PID) Controllers are the popular technique to control any process. In this paper, Proportional-Integral (PI) and Proportional-Integral-Derivative (PID) controllers are used to control the vibrations to give smooth response of the bus suspension system and carry-out their comparison on the basis of time and frequency using Matlab environment. The simulation and implementation of the controller is done using Matlab/Simulink. C. Poussot-Vassal et.al [8] have studied how the frequency modulation at mid and high frequency can be trade-off to overcome the optimal control of damping and how the best performances in terms of comfort are reflected in terms of handling and vice verse. In this a semi-active suspension system is described as a quarter car model, equipped with a controllable damper, providing an effective representation of the semi-active suspension dynamics. The main aim of this study is to propose a methodology allowing for evaluation of handling and comfort lower theoretical filtering bounds, which can be used as a benchmark for any semi-active control design.

Ammar A. Aldair et.al [9] has developed the design of a robust controller for full vehicle nonlinear active suspension systems which is used to control and handle the nonlinearities faster than other conventional controllers. Neural controller are devised to adjust the hydraulic actuators which forces to minimize the vertical displacement at each suspension point when travelling on rough roads and to reduce the inclination of the vehicle during sudden manoeuvres such as sharp bending and braking. The robustness of the proposed controller is being assessed by comparing with Fractional Order PID (FOPID) controller. To validate the robustness of the proposed approach, the cases with six types of disturbances will be investigated. The results show that intelligent neural controller have improved dynamic response measured by a decreased cost function. Kommalapati. Rameshbabu et.al [10] have studied about the shock absorber which is used to reduces the effect of travelling over rough ground, leading to improved ride quality , and increase in comfort. In this a shock absorber is designed and a 3D model is created using Pro/Engineer. The model is also changed by changing the thickness of the spring. Structural analysis and modal analysis are done on the shock absorber by varying material for spring, Spring Steel and Beryllium Copper. The analysis is done by considering loads, bike weight, single person and 2 persons. Structural analysis is done to validate the strength and modal analysis is done to determine the displacements for different frequencies for number of modes. Comparison is done for two materials to verify


20

best material for spring in Shock absorber. Faraz Ahmed Ansar et.al [11] have constructed an active suspension control for a quarter car model to improve the riding quality without compromising the handling characteristic by directly controlling the suspension forces to suit the road and driving conditions. In order to achieve the desired ride comfort, road handling and to solve the uncertainties, a sliding mode control technique is presented. A nonlinear surface is used to ensure fast convergence of vehicle’s vertical velocity which changes the system’s damping. Extensive simulations are performed and the results obtained shows that the proposed controller perform well in improving the ride comfort and road handling for the quarter car model using the hydraulically actuated suspension system. S.Pathmasharma et.al [12] have studied about improving the suspension system which increases the market share when a vehicle is provided with maximum comfort. This improvement is done by the analysis of the existing of the suspension system. The data of the Passenger vehicle suspension system of the existing vehicle are collected and a model is created using UG. Automatic dynamics of Mechanical System (ADAMS) has become an important feature of roadside hardware design and analysis in recent year. The analysis of existing model is carried out using ADAMS which is used to determine the forces acting on components of suspension system. With the view of minimizing the forces acting on the components of the suspension system all of the critical components of the suspension system such as mounting points, track width and mass were modified and incorporated into the new model along with the capacity to make the most important components force act with time by carefully modeling the geometric details such as mounting points. It is believed that these modifications significantly improve the performance of simulating impacts with off road side.V.V. Jagirdar et.al [13] has developed Wishbone structure for double wishbone front-independent Suspension for a military truck application is presented. At present, the vehicle is equipped with rigid axle with leaf springs. There are two aspects that dictate the design of wishbone structure, viz. the path of relative motion between the constituents of the suspension system and the forces transmitted between them. Also, enhancement of mobility was made possible by maintaining the live axle in the system. A double wishbone, double coil spring with twin damper configuration was employed for this application. MBD Analysis was carried out using MSC ADAMS. A double wishbone independent suspension has been designed for the front axle and has been successfully integrated with the vehicle. Niranjan Singh [14] has studied about the

fatigue stress analysis of springs used in automobiles. To isolate the structure and the occupants from shocks and vibrations generated by the road surface the automobile suspension systems is used. The suspension systems basically consist of all the elements that provide the connection between the tyres and the vehicle body. A spring stores mechanical energy and act as an elastic body that can be twisted, pulled, or stretched by some force. It returns to their original shape when the force is released. Kalaivani Rajagopa et.al [15] has developed Multi Objective Optimization (MOO) of Vehicle Active Suspension System (VASS) with a hybrid Differential Evolution (DE) based Biogeography-Based Optimization (BBO) (DEBBO) for the parameter tuning of Proportional Integral Derivative (PID) controller. Initially a conventional PID controller, secondly a BBO, an rising nature enthused global optimization procedure based on the study of the ecological distribution of biological organisms and a hybridized DEBBO algorithm which inherits the behaviors of BBO and DE have been used to find the tuning parameters of the PID controller to improve the performance of VASS by considering a MOO function as the performance index. Simulations of passive system, active system having PID controller with and without optimizations have been performed by considering dual and triple bump kind of road disturbances in MATLAB/ Simulink environment. The simulation results show the effectiveness of DEBBO based PID in achieving the goal. Abdolvahab Agharkakli et.al [16] has investigated whether the active suspension system is synthesized based on the Linear Quadratic Regulator (LQR) control technique or a quarter car model. By using road profile comparison between passive and active suspensions system are performed. The mathematical model for the passive and active suspensions systems for quarter car model and an active suspension control for a quarter car model subject to excitation from a road profile using LQR controller. The performance of this controller is been determined by performing computer simulations using the MATLAB and SIMULINK toolbox. A.Purushotham [17] has developed a two-dimensional mathematical model of a McPherson suspension. There are two main suspension systems namely: double wishbone suspension system and McPherson suspension. The MacPherson strut setup is still being used on high performance cars such as the Porsche 911, several Mercedes-Benz models and lower BMW models due to its light weight, design simplicity and low manufacturing cost. The McPherson suspension model considers not only the vertical motion of the chassis(sprung mass) but also rotation and translation for unsprung mass(wheel assembly). Furthermore, this


21

model includes wheel mass and its moment of inertia about the longitudinal axis. Yousfi Khemissi [18] have studied about the proposition of sliding mode position controller of the magnetic suspension ball system which is a mechatronic system already acknowledged and accepted by the field experts. The main function of the sliding mode control (SMC) Controller is to maintain the balance between the magnetic force and the ball's weight. The proposed controller guarantee the asymptotic regulation of the states of the system to their desired values. Complete mathematical models of the electrical, mechanical and magnetic suspension system are also developed.

III. REVIEW ON SPRINGS

U. S. Ramakanth et.al [19] have studied about multi leaf springs having nine leaves where generally a leaf springs which are one of the oldest suspension components are used, especially in commercial vehicles. The automobile industries have shown interests in replacement of steel springs with composite leaf springs due to high strength to weight ratio. In this a Finite element approach for analysis of a multi leaf springs using Ansys software is carried out. The model is generated using solid works and imported in Ansys. Fatigue analysis of leaf springs is carried out for steel leaf springs, and Static analysis for steel leaf springs, composite leaf springs and hybrid leaf springs.

Pankaj Saini et.al [20] has developed design and analysis of composite leaf spring where the comparison of the stresses and weight saving of composite leaf spring with that of steel leaf spring is done. Now a days the Automobile Industry has great interest for replacement of steel leaf spring with that of composite leaf spring, since the composite materials has high strength to weight ratio, good corrosion resistance. The composite leaf spring is used to reducing weight while increasing or maintaining strength of products which is getting to be highly important research issue in this modern world. The design parameters were selected and analyzed with the objective of minimizing weight of the composite leaf spring as compared to the steel leaf spring.

Ghodake A. P. et.al [21] have studied about the new materials which can be used for leaf spring and then selected glass fiber reinforced plastic (GFRP) and the polyester resin (NETPOL 1011) which is used against conventional steel. This study is been done because the Automobile Industry has shown keen interest for replacement of steel leaf spring with that of glass fiber composite leaf spring, since the composite material has high strength to weight ratio, good corrosion resistance

and tailor-able properties. The numerical analysis is carried via finite element analysis using ANSYS software. Stresses, deflection and strain energy results for both steel and composite leaf spring material were obtained. Result shows that, the composite spring has maximum strain energy than steel leaf spring and weight of composite spring was nearly reduced up to 85% compared with steel material.

Baviskar A. C. et.al [22] have investigated for improving the performance of leaf spring. The study states that the suspension system in a vehicle which significantly affects the behavior of vehicle, i.e. vibration characteristics including ride comfort, stability etc. Leaf springs are commonly used in the vehicle suspension system and are subjected to millions of varying stress cycles leading to fatigue failure. In this investigation a lot of review on some papers on the design and analysis leaf spring performance and fatigue life prediction of leaf spring is seen. There is also the analysis of failure in leaf spring. Also the analysis of leaf spring with ansys is done. Abdul Karim Selman Abdul Karim et.al [23] have investigated about a rational technique to design leaf spring for light truck . The Light truck is used for the world economic growth since it was used in transportation for various kinds of commodities. Leaf spring is the most admire alternative utilized in the suspension system of this specific truck due to their low production cost, reliability and maintainability. Simulation resembles to constrained condition when mounting on the vehicles were undertaken to examine the stresses distribution for each leaf.

IV. REVIEW ON VIBRATIONS

Saikat Dutta et.al[24] has developed a phenomenological model of MR damper in which Magnetorheological (MR) fluids can produce good controllable damping force under application of magnetic field. MR damper can be used as effective element in semi active vibration control. Out of various semi-active control strategies, the on-off sky-hook control strategy is used in this work. A single degree of freedom system with MR damper under sinusoidal excitation is first studied to check the performance of the proposed on-off controller with MR damper. By changing the input voltage according to the control scheme the parameters of MR damper in the model are varied. Performances of this controller for two types of road profiles, namely, sinusoidal road profile, random road profile are studied. The control strategy is found to be effective for a quarter car model. To examine optimal damper force vehicle required to isolate


22

the vibration several performance indices have been chosen which are functions of vehicle performance measures such as sprung mass acceleration, vehicle handling and working space. Saeed Asiri et.al [25] have studied about new class of periodic mounts for isolating the vibration transmission from vehicle engine to the car body and seats is presented. Periodic mounts exhibit unique dynamic characteristics that make them act as mechanical filters for wave propagation. As a result, waves can propagate along the periodic amounts only within specific frequency bands called the “PassBands” and wave propagation is completely blocked within other frequency bands called the “Stop Bands”.

Deulgaonkar V.R et.al [26] has studied the correlation between pressure and vibration levels of different sources with acoustical and structure transfer path and at the same time the effectiveness of the firewall, silencers and engine mounts are checked and compared. The various automotives produce a lot of noise & vibrations for which a reduction technique is studied through energy flow path. Various international and Indian standards for vehicles consider two types of noise measurement i.e. pass by noise and stationary noise. In this study the appropriateness of SN test for in use vehicle is discussed. Two vehicles of same class but of different makes were compared and evaluated for interior noise and vibration levels. Yogendra S. Rajput et.al [27] has investigated about the vibration characteristics of the frame including the natural frequencies and mode shapes. The off-road racing vehicle for the SAEINDIA’s BAJA competition has raised the value of dynamic analysis under severe uneven loading. The dynamic analysis is carried out by the finite element method simulation there by predicting failure modes of the vehicle frame under vibration analysis. B. Soleimani et.al [28] have developed the dynamic response of the wheel on irregular rail track which is been analyzed with analytical approach using the method of Multiple Scales (MMS). The Hertzian contact theory is used to obtain the relationship between normal contact force and the displacement of the mass center of the wheel. Analytical approach is expanded for performance of train’s wheel travelling on the rail. The Wheel/rail contact simulation is one of the most complicated problems in the modeling of railway vehicles. The wheel/rail interaction plays a unique role in rail vehicle dynamics. A. Bala Raju et.al [29] have developed the equations of motion and studied the vibrations of the suspension system under different disturbing conditions. The suspension system of an automobile helps to support the car body, engine and passengers, and at the same time absorbs shocks

received from the ground while vehicle moves on rough roads. Haiping Du et.al [30] have studied about the active control of seat suspension to reduce vertical vibration transmitted from uneven road profile to driver body and to provide ride comfort, in particular, commercial vehicles, to reduce driver fatigue while long hours driving. The control problem will be firstly studied by proposing an integrated seat suspension model which includes vehicle chassis suspension, seat suspension, and driver body model. A static output feedback controller is then designed for the seat suspension with using measurement available signals. Driver mass variation and actuator saturation are also considered in the controller design process. The conditions for designing such a controller are derived in terms of linear matrix inequalities (LMIs). Finally, numerical simulations are used to validate the effectiveness of the proposed control strategy. Zulkifli Mohd Nopiah et.al [31] has investigated the effects of vibration to noise in passenger car cabin generally the vibration is caused by two main sources: engine transmission and interaction between tyre and road surface. The noise which produced by the car system can cause hearing impairment, hypertension, annoyance and sometimes can decrease the driving focus which may cause an accident. Vehicle acoustical comfort index (VACI) was used to evaluate the noise annoyance level and vibration dose value (VDV) was used to evaluate the vibration level. By using the changes trend of noise and vibration level depending to engine speeds, optimization model was proposed to optimize the vibration level in the passenger car cabin.

V. CONCLUSIONS

The following observations are drawn from the investigation of the previous researchers mentioned in the introduction.

Ride comfort and handling characteristics of semi active suspension system is better as compared to conventional passive suspension system and less expensive than the active suspension system. There are two criteria of good vehicle suspension performance: the first one is typically their ability to provide good road handling and the other is grantee the passenger comfort. The main disturbance affecting these two criteria is terrain irregularities. Active suspension control system reduces these undesirable effects by isolating car body motion from vibrations at the wheels. Suspension control is highly a difficult control problem due to the complicated relationship between its components and parameters. The research was carried out in suspension control system cover a broad range of design issues and


23

challenges. Conventionally, the vibration energy of vehicle suspension is dissipated as heat by shock absorber, which wastes a considerable number of resources. The composite spring has maximum strain energy than steel leaf spring and weight of composite spring was nearly reduced up to 85% compared with steel material. The design and analysis of leaf spring performance and fatigue life prediction of leaf spring is reviewed also the analysis of leaf spring with ANSYS is done. The rational technique to design leaf spring for light truck is investigated. Simulation resembles to constrained condition when mounting on the vehicles were undertaken to examine the stresses distribution for each leaf. By using the changes trend of noise and vibration level depending to engine speeds, optimization model was proposed to optimize the vibration level in the passenger car cabin. The vibration characteristics of the frame including the natural frequencies and mode shapes are studied where the dynamic analysis is carried out by the finite element method simulation thereby predicting failure modes of the vehicle frame under vibration analysis.

VI. ACKNOWLEDGMENT

My special thanks to Dr. A. Siva Kumar M.Tech, Ph.D, MISTE, MIE, Professor & Head in Mechanical Department for guiding me in the right way to complete my paper in the right time. Last but far from least, I also thank my parents, family members and my friends for their moral support and constant encouragement.

VII. REFERENCES

[1] Rahul N. Sandage, Pranit M. Pati, S.A. Patil, “Simulation Analysis of 2dof Quarter Car Semi-Active Suspension System to Improve Ride Comfort”, International Journal of Application or Innovation in Engineering & Management (IJAIEM), Vol: 2, Issue: 12, December 2013.

[2] Yahaya Md. Sam, Johari H.S. Osman, M. Ruddin A. Ghani, “A class of proportional-integral sliding mode control with application to active suspension system”. Received 20 February 2002; received in revised form 16 October 2002; August 2003.

[3] Ayman A. Aly and Farhan Salem, “A.Vehicle Suspension Systems Control: A Review”. International Journal Of Control, Automation And Systems VOL:2, Issue:2 July 2013.

[4] Zhang Jinqiu, Peng Zhi-zhao, Zhang Lei, Zhang Y, “A Review on Energy-Regenerative Suspension Systems for

Vehicles” Proceedings of the World Congress on Engineering 2013 Vol :3, WCE 2013, July 3-5, 2013.

[5] A. A. Aldair and W. J. Wang , “Design An Intelligent Controller For Full Vehicle Nonlinear Active Suspension Systems”. International Journal On Smart Sensing And Intelligent Systems, Vol: 4, Issue:2, June 2011.

[6] Suleiman Abu-Ein and Sayel M. Fayyad, “Electromagnetic Suspension System: Circuit And Simulation” International Journal of Modeling and Optimization, Vol:3, Issue:5, October 2013.

[7] Sheilza Jain and Swati Gaur “ Vibration Control of Bus Suspension System using PI and PID Controller” International Journal of Advances in Engineering Sciences Vol:3, July, 2013.

[8] C. Poussot-Vassal, S.M. Savaresi, C. Spelta, O. Sename and L. Dugard, “A Methodology for Optimal Semi-Active Suspension Systems Performance Evaluation”. 49th IEEE Conference on Decision and Control (CDC 2010) .

[9] Ammar A. Aldair and Weiji J. Wang, “Neural Controller Based Full Vehicle Nonlinear Active Suspension Systems with Hydraulic Actuators”, International Journal of Control and Automation, Vol: 4, Issue: 2, June 2011.

[10] Kommalapati Rameshbabu, Tippa Bhimasankara Rao “Design Evaluation of a Two Wheeler Suspension System for Variable Load “International Journal of Computational Engineering Research, Vol:03, Issue: 4, PP:279, April 2013.

[11] Faraz Ahmed Ansari, RajShree Taparia “Modeling, Analysis and Control of Active Suspension System using Sliding Mode Control and Disturbance Observer “International Journal of Scientific and Research Publications, Volume:3, Issue:1, January 2013.

[12] S. Pathmasharma, J. K. Suresh, P. Viswanathan and R. Subramanian, “Analysis of Passenger Car Suspension System Using Adams”. International Journal of Science, Engineering and Technology Research (IJSETR), Vol:2, Issue: 5, May 2013.

[13] V.V. Jagirdar, M.S. Dadar, and V.P. Sulakhe, "Wishbone Structure for Front Independent Suspension of a Military Truck" Defence Science Journal, Vol: 60, Issue: 2, pp. 178-183, March 2010.

[14] Niranjan Singh, “General Review Of Mechanical Springs Used In Automobiles Suspension System” International Journal of Advanced Engineering Research and Studies, Vol :3, Issue:1, December 2013.

[15] Kalaivani Rajagopal, Lakshmi Ponnusamy, "Multi Objective Optimization Of Vehicle Active Suspension System Using Debbo Based Pid Controller", International Journal of Engineering and Technology (IJET) , Vol:6 Issue:1, March 2014.

[16] Abdol vahab Agharkakli, Chavan U.S, Dr. Phvithran S, “Simulation And Analysis Of Passive And Active Suspension System Using Quarter Car Model For Non Uniform Road Profile”, International Journal of Engineering Research and Applications (IJERA), Vol: 2, Issue :5, PP:900-906, October 2012.


24

[17] A. Purushotham, “Comparative Simulation studies on MacPherson Suspension System”, International Journal of Modern Engineering Research (IJMER), Vol:3, Issue:3, PP:1377-1381, June. 2013.

[18] Yousfi Khemissi, “Control Using Sliding Mode Of the Magnetic Suspension System”, International Journal of Electrical & Computer Sciences IJECS-IJENS, Vol:10, Issue :3, June 2010.

[19] U. S. Ramakanth & k. Sowjanya, “Design And Analysis Of Automotive Multi-Leaf Springs Using composite Materials”, International Journal of Mechanical Production Engineering Research and Development (IJMPERD) ISSN 2249-6890, Vol: 3, Issue: 1, PP: 155-162, March 2013.

[20] Pankaj Saini, Ashish Goel, Dushyant Kumar, “Design And Analysis Of Composite Leaf Spring for Light Vehicles”, International Journal of Innovative Research in Science, Engineering and Technology , Vol : 2, Issue :5, May 2013.

[21] Ghodake A. P, Patil K.N, “Analysis of Steel and Composite Leaf Spring for Vehicle”, IOSR Journal of Mechanical and Civil Engineering (IOSR-JMCE), Vol:5, Issue :4, PP 68-76, Feb.2013.

[22] Baviskar A. C, Bhamre V. G, Sarode S. S,“ Design and Analysis of a Leaf Spring for automobile suspension system”, International Journal of Emerging Technology and Advanced Engineering, Vol:3, Issue:6, June 2013.

[23] Abdul Karim Selman Abdul Karim, and Arshed Abdul Hamed Mohammed, “Studying The Stress Analysis In Leaf Spring By Finite Elements Method”, Diyala Journal of Engineering Sciences, Vol :3, Issue:1, PP: 47-64, June 2010.

[24] Saikat Dutta, Sangolla Narahari, Goutam Chakraborty, “Semi-active vibration isolation of a quarter car model under random road excitations using Magneto rheological damper”,1st International and 16th National Conference on Machines and Mechanisms (iNaCoMM2013), Dec 2013.

[25] Saeed Asiri and A.A.N. Aljawi, “Periodic Mounts to Isolate the Vibrations of Automotive Vehicle Engine”, JKAU: Eng. Sci., Vol:17, Issue:1, PP:97-115, 2006.

[26] Deulgaonkar V.R, Dr.Kallurkar S.P, Dr. Mattani A.G, “Review and Diagnostics of noise and vibrations in automobiles”, International Journal of Modern Engineering Research (IJMER), Vol:1, Issue:2, PP:242-246.

[27] Yogendra S. Rajput1, Vikas Sharma1, Shivam Sharma1, Gaurav Saxena, “ A Vibration Analysis Of Vehicle Frame”, International Journal of Engineering Research and Applications (IJERA), Vol : 3, Issue : 2, PP:348-350, April 2013.

[28] B. Soleimani1, M.M. jalili, “Analytical Approach to Vibration Analysis Of the Wheel-rail contact”, International Journal of Automotive Engineering, Vol: 3, Issue : 3, Sept 2013.

[29] Bala Raju

and R. Venkatachalam, “Analysis of Vibrations of Automobile Suspension System Using Full-car

Model”, International Journal of Scientific & Engineering Research, Vol : 4, Issue: 9, September 2013.

[30] Haiping Du, Weihua Li and Nong Zhang, “Vibration Control of Vehicle Seat Integrating with Chassis Suspension and Driver Body Model”, Advances in Structural Engineering, Vol : 16, Issue : 1, 2013.

[31] Zulkifli Mohd Nopiah, Ahmad Kadri Junoh, Wan Zuki Azman Wan Muhamad, Mohd Jailani Mohd Nor, Ahmad Kamal Ariffin Mohd. Ihsan, Mohammad Hosseini Fouladi, “Linear Programming: Optimization of Noise and Vibration Model in Passenger Car Cabin”, International Journal of Soft Computing And Softwar Engineering (JSCSE), Vol :2,Issue :1, 2012.


25

Dynamic Analysis of Structures Using Constrained Layer Damping Technique

Ch. Rajesh

Dept of Mechanical Engineering,

Faculty of science & Technology,

IFHE University

Hyderabad- 501203, India.

J. Suresh Kumar

Dept of Mechanical Engineering,

JNTU College of Engineering,

Hyderabad-500085, India

Abstract: This Paper deals with the dynamic analysis of the structures designed to support engines are subjected to vibration due to dynamic excitations. When the exciting force is oscillatory, the system is forced to vibrate at the excitation frequency. If the frequency of excitation coincides with one of the natural frequencies of the system, a condition of resonance is encountered. In this paper an attempt is made to identifying suitable damping treatment for a motor driven compressor foundation used in marine structures. It involves to finding the natural frequencies of the structural foundation. An experimental investigation is carried out to find the natural frequencies of structural foundation using FFT analyzer. The results obtained are compared with the results obtained from ANSYS.

Keywords: CLD; natural frequency; mode shapes; viscoelastic material; FFT analyzer

I. INTRODUCTION

Vibration measurements have been performed in the

industry since the advent of the steam engine. These measurements were resorted to only in times of difficulty. During olden days, the machines were very few, slow, and quite robust. The present day engineer has to contend with faster, sensitive machinery with very high requirements of production rates and quality. Increased reliability of the machines and economic feasibility of the maintenance programs are the primary interests of the engineer today. In many programs involving maintenance, the utility of vibration measurement as a tool for assessment of the machinery condition is well known. Excessive vibration can endanger the safety of structures. Another aspect of vibration, which is of interest to defence applications is the radiation of vibration as noise. Vibration, depending on the damping present in the system, decays with time, and is converted into heat, or is radiated away as noise. This noise acts as a give-away to an underwater/surface vessel. This noise needs to be controlled to avoid ‘detection’, and one of the means of noise reduction is to reduce the vibration at source.

II. FORMULATION

The vibration transducer is a device that is held on attached to the machine to convert the machines mechanical vibration into an electrical signal that can be processed by the associates instrument into measurable characteristics of vibration amplitude, frequency and phase. An accelerometer is a transducer whose output is proportional to the accelerometer input. A velocity pick up is a transducer whose output is proportional to velocity input. A displacement pick up is a transducer whose output is proportional to displacement input. Accelerometer used is a self-generating device that produces a voltage output proportional to vibration acceleration.

The propagation or transient problems: Transient problems are time dependent. In finding the response of a body under time varying force in solid mechanics Propagation problems

[A] d2 x/dt2 + [B] dx/dt + Cx = F(x, t), t>0

Subjected to boundary conditions

[D]x = g, t >0

Initial conditions are

x = Xt, t = 0

Where [A][B][C] and [D] are square matrix whose elements are known. X is the vector unknown or field variable, is the Eigen value, t is the time parameter and F is the vector whose elements are known functions of X and t.

III. EXPERIMENTAL SETUP

An experimental modal analysis is carried by shock excitation. An impact hammer as shown in Fig. 1 is used to generate force required to excite various modes of the structure as shown in Fig. 2. A steel tip is used to cover a wide frequency range which has a high peak force with a narrow spectrum. The force is measured by a piezoelectric disc incorporated in the body of the hammer. It covers a frequency range up to


26

10 kHz the duration of pulses of the order of few milliseconds. Certain precautions have to be taken in carrying out the test. If the hammer is too heavy in relation to the response of the structure, there is risk off double hitting where the structure rebounds and hits the hammer. Since the duration of the signal is short the response has to be windowed.

Fig 1: IMPACT HAMMER

Fig 2: Experimental Set Up For Impact Hammer Test

IV. RESULTS AND DISCUSSIONS

Figure 3 shows the auto spectrum response of the structure measured from FFT analyzer. From the fig.3 it is noticed that for free condition the first fundamental natural frequency of the structure is 65.5 Hz, where as from the ANSYS (FEA) is 66.202Hz. For fixed condition the fist fundamental natural frequency of the structure obtained from the experiment is 321.16 Hz where as from ANSYS is 324.6 Hz

Autospectrum(RESPONCE) - Input (Magnitude)

Working : Input : Input : FFT Analyzer1

40 80 120 160 200

1m

10m

100m

1

10

[Hz]

[m/s²] Autospectrum(RESPONCE) - Input (Magnitude)

Working : Input : Input : FFT Analyzer1

40 80 120 160 200

1m

10m

100m

1

10

[Hz]

[m/s²]

Fig 3. Auto Spectrum (Responce) – Input

Fig. 4 Response of the Structure before and after Damping

Fig. 5 Damping Response of the Structure

Fig 4 shows the response of the structure before and after damping. From the Fig it is observed that the


27

Vibrations are decreasing from without internal damping to with internal damping. The damping response of the structure for different constrained layer thicknesses is shown in Fig 5. It is observed that the 6mm constrained layer for external damping treatment (CLD) vibrations are higher in between 800Hz to 1400Hz compare to other thickness of layer.

V. CONCLUSIONS

The experiments were conducted successfully to find the vibration responses of structures used in marine applications. The results obtained from experimentation and ANSYS are compared. The percentage variation in the results obtained from experimentation and ANSYS is about 1.5. The vibration response is drastically decreasing from without damping to with damping. From the study carried out it concluded that the 6mm layer with constrained layer treatment is better to reduce the vibration response compare to all other layers.

VI. REFERENCES

[1] Experimental Modal Analysis, Peter Avitabile, Journal of Sound and Vibration, January-2001, pg 20-31.

[2] Material Damping Properties, Matthew D. Black, Mohan D. Rao, Journal of Sound and Vibration, August-2001, pg 24-28.

[3] Active Constraint layer Damping, A. Baz, Journal of Sound and Vibration, Vol.28, pg 18-21.

[4] Vibration control in Machines and Structures using Viscoelastic Damping, B.C. Nakra, Journal of Sound and Vibration, Vol.221(3), pg 449-463.

[5] Vibration Analysis of Sub Marine structures, Ch.Rajesh, J. Suresh Kumar , P. Ravikanth Raju, International conference on Multi Body Dynamics 2011, pp 199 -203.

[6] Active and Passive Noise Control of Flexible Structures using combination of Magneto and Ferro- Magnetic Alloys, B.R. Vidyashankar, G.R. Tomilision and B. Bhattacharya, Journal of Sound and Vibration, Vol. 91(4), pg 601-603.

[7] A Refined Dynamic Theory of Visoelastic Laminated Composites (Part 2), Mingi and G.A.Birlik, Journal of Sound and Vibration, Vol.130 (1), pg 55-67.

[8] Vibration Control with Viscoelastic Materials, B.C. Nakra, Sound and Vibration Digest, Vol. 16, pg 17-22.

[9] Hand Book of Noise and Vibration Control, Antony Barber, Elsevier Advanced Technology, 1992 (6th Edition).

[10] Vibration Damping, Ahid D. Nashif, David I.G.Jones, John. P. Henderson, Wiley Inter Science Publication, 1985.

[11] Hand Book of Noise Control, Vol. 1., Cyril M. Harris, McGraw-Hill Book Company, 1973.

[12] Hand Book of Noise Control, Vol. 2., Cyril M. Harris, McGraw-Hill Book Company, 1979.

[13] Hand Book of Plastics and Electrometers, Charles A.Harper, McGraw-Hill Book Company, 1975.


28

Design, Modeling and Structural Analysis of Helical Gear for ceramic and steel material by using ANSYS

Niyamat.A.Mulla

M.Tech Final Year Student

Mechanical Engineering Department,

Malla Reddy College of Engineering & Technology, Hyderabad, India

[email protected]

K.Bicha

Assistant Professor

Mechanical Engineering Department,

Malla Reddy College of Engineering & Technology,

Hyderabad, India

[email protected]

Abstract— This project mainly deals with the design and analysis of helical gear with involutes profile. The involutes gear profile is the most commonly used system for gearing today. In an involutes gear, the profiles of the teeth are involutes of a circle. In involutes gear design contact between a pair of gear teeth occurs at a single instantaneous point. Rotation of the gears causes the location of this contact point to move across the respective tooth surfaces. The teeth on helical gears are cut at an angle to the face of the gear. When two teeth on a helical gear system engage, the contact starts at one end of the tooth and gradually spreads as the gears rotate, until the two teeth are in full engagement .This gradual engagement makes helical gears operate much more smoothly and quietly than spur gears. For this reason, helical gears are used in almost all power transmissions. One interesting thing about helical gears is that if the angles of the gear teeth are correct, they can be mounted on perpendicular shafts, adjusting the rotation angle by 90 degrees. Under this project the Helical gear with involutes profile is designed with the help of CATIA V5R16 software , modal and static structural analysis is carried by the ANSYS software .

Keywords— Gear Specification, Gear modeling, Modal & Structural analysis

I. INTRODUCTION

Gears are most commonly used for power

transmission in all the modern devices. These toothed wheels are used to change the speed or power between input and output. They have gained wide range of acceptance in all kinds of applications and have been used extensively in the high-speed marine engines. In the present era of sophisticated technology, gear design has evolved to a high degree of perfection. The design and manufacture of precision cut gears, made from materials of high strength, have made it possible to produce gears which are

capable of transmitting extremely large loads at extremely high circumferential speeds with very little noise, vibration and other undesirable aspects of gear drives. A gear is a toothed wheel having a special tooth space of profile enabling it to mesh smoothly with other gears and power transmission takes place from one shaft to other by means of successive engagement of teeth. Gears operate in pairs, the smallest of the pair being called “pinion” and the larger one “gear”. Usually the pinion drives the gear and the system acts as a speed reducer and torque converter.

II. HELICAL GEAR SPECIFICATION

Helical gears offer a refinement over spur gears. The leading edges of the teeth are not parallel to the axis of rotation, but are set at an angle. Since the gear is curved, this angling causes the tooth shape to be a segment of a helix. Helical gears can be meshed in a parallel or crossed orientations. The former refers to when the shafts are parallel to each other; this is the most common orientation. In the latter, the shafts are non-parallel. The angled teeth engage more gradually than do spur gear teeth causing them to run more smoothly and quietly. With parallel helical gears, each pair of teeth first make contact at a single point at one side of the gear wheel; a moving curve of contact then grows gradually across the tooth face to a maximum then recedes until the teeth break contact at a single point on the opposite side. In spur gears teeth suddenly meet at a line contact across their entire width causing stress and noise. Spur gears make a characteristic whine at high speeds and cannot take as much torque as helical gears. Whereas spur gears are used for low speed applications and those situations where noise control is not a problem, the use of helical gears is


29

indicated when the application involves high speeds, large power transmission, or where noise abatement is important. The speed is considered to be high when the pitch line velocity exceeds 25 m/s Quite commonly helical gears are used with the helix angle of one having the negative of the helix angle of the other; such a pair might also be referred to as having a right-handed helix and a left-handed helix of equal angles. The two equal but opposite angles add to zero: the angle between shafts is zero – that is, the shafts are parallel. Where the sum or the difference (as described in the equations above) is not zero the shafts are crossed. For shafts crossed at right angles the helix angles are of the same hand because they must add to 90 degrees.

a) Helical Gear Nomenclature

Helix angle, ψ

Angle between a tangent to the helix and the gear axis. Is zero in the limiting case of a spur gear.

Normal circular pitch, pn

Circular pitch in the plane normal to the teeth.

Transverse circular pitch, p

Circular pitch in the plane of rotation of the gear. Sometimes just called "circular pitch". pn = pcos(ψ)

Fig: 1 helical gear nomenclature

Helical gear geometric propotion

p = Circular pitch = d g. p / z g = d p. p / z p

p n = Normal circular pitch = p .cosβ

P n =Normal diametrical pitch = P /cosβ

p x = Axial pitch = p c /tanβ

m n =Normal module = m / cosβ

α n = Normal pressure angle = tan -1 ( tanα.cos β )

β =Helix angle

d g = Pitch diameter gear = z g. m

d p = Pitch diameter pinion = z p. m

a =Center distance = ( z p + z g )* m n /2 cos β

a a = Addendum = m

a f =Dedendum = 1.25*m

Fig: 2 Tool used in gear geometry

III. MODELING OF HELICAL GEAR USING

CATIA

It was developed by Dassault Systèmes in 1981 and it is located in French. Versions of CATIA are V1, V2, V3, V4, V5 and V6 more companies are using from V4 only. Now in the market many companies are using V5R16 and in V5 we have many versions from V5R1 to V5R21.It is a tool based software these tools we call as features, so it is a feature based software .It is a parametric software, parametric mean while designing or after completing the design we can change the parameters of the component. CATIA stand for Computer Aided Three Dimensional Interactive Application. It is a product modeling software can be custom-made via Application Programming Interfaces (API). CATIA V5 features are parametric solid/surface-based wrap up which uses NURBS as the interior surface representation and has quite a lot of workbenches that make available KBE support(1).

Before creating helical gear we should know the specifications of helical gear based on the data and formulas we can design the helical gear.

Specification of Helical gear

rb - base cylinder radius

r - pitch circle radius

rk - outside circle radius

rf - root radius

a - pressure angle (20deg)


30

m – Modulo (in our example 20) m=p/3.14159 where p is circular pitch 2r=m*z

z - Number of teeth (in our example 30)

The following figure shows complete helical gear model which is generated by using CATIA and then it is retrieved into ANSYS using IGES files.

Fig: 3 shows Designed helical gear

IV. ANSYS

The ANSYS Workbench platform is the framework upon which the industry’s broadest and deepest suite of advanced engineering simulation technology is built. An innovative project schematic view ties together the entire simulation process, guiding the user through even complex multi physics analyses with drag-and-drop simplicity. With bi-directional CAD connectivity, powerful highly-automated meshing, a project-level update mechanism, pervasive parameter management and integrated optimization tools, the ANSYS Workbench platform delivers unprecedented productivity, enabling Simulation Driven Product Development. In this project ANSYS 13.0 played a major role, all the analysis was done with the implementation of ANSYS. Mainly Modal ANSYS and Static Structural ANALYSIS were done in this Project.

Modal Analysis

In this Modal ANSYS, only the deformation of the component was calculated with applying forces and boundary conditions. The deformation will be calculated at different natural frequencies and it was mentioned as different modes. Applying of the boundary conditions will give you the specified directional deformation along with the total

deformation.In this section modal analysis is done by using ANSYS and which is shown in result table.

Structural Analysis

After the preprocessing, the solution has to be done. From solution phase, choose the new analysis as static. Then solve the current load step option. The solution will be done. A model is generated using CATIA software and then it is retrieved into ANSYS using IGES files.

In this section the Structural analysis is to be done .The following Figure shows total deformation of gear, the structural analysis of helical gear for aluminum and steel at load 100Mpa, 200Mpa, 300Mpa, 400 Mpa, 500 Mpa.

Structural Analysis for Aluminum

Fig: 4.1 Total deformations at 100 Mpa




31



Structural Analysis for Structural Steel






V. RESULTS

The analysis is carried out by ANSYS. The following First table shows the modal analysis and second table shows the comparison of equivalent stresses & Total deformation for aluminum and Structural steel.


32

Table: 1 Modal Analysis

S.No Equivalent Stresses

(Mpa)

Total Deformation

(mm)

1 3609.7 7.0487

2 4346.2 10.334

3 4346.7 10.338

4 4668.9 7.1834

5 5243.8 11.19

6 5244 11.189

Table-2 Comparison of equivalent stresses & Total deformation between aluminum and structural

steel

S.NO

L

O

A

D

Equivalent stress

(Mpa)

Total Deformation

(mm)

Aluminum

Structural

Steel

Aluminum

Structural

Steel

1 100 0.81445 2.2572 0.0005591

9 0.000556

2 200 3.2578 9.0288 0.0022368 0.002229

3 300 7.3301 20.315 0.0050327 0.050127

4 400 13.031 30.115 0.008947 0.008911

5 500 20.361 56.43 0.01398 0.013924

VI. CONCLUSION

1. From the tables, it is observed that bending and compressive stresses of ceramics are less than that of the steel.

2. Bending and compressive stresses were obtained theoretically & by using ansys software for both ceramic& steel.

3. Weight reduction is a very important criterion in the helical gears.

4. Hence aluminum material is preferred.

VII. FUTURE SCOPE OF THE WORK

In the present investigation of static analysis, a high speed helical gear is analyzed by fem package ansys. As a future work, modal analysis and harmonic analysis of the gear can be performed to find out the mode

VIII. ACKNOWLEDGMENT

I have great pleasure in presenting this paper on “Design, Modal and Structural Analysis of Helical Gear for Ceramic and Steel material by Using ANSYS”. I take this opportunity to express sincere appreciation and deep sense of gratitude to my project guide, Assist Prof. K. Bicha, MRCET, Hyderabad. For his whole hearted co-operation, valuable guidance and perpetual encouragement and inspiration during the path of his work. I remain ever indebted to him for the keen interest shown and moral support offered all through pursuance of this work.

I would like to express my gratitude to M.Amarnadha Reddy Professor, Head of the Department of Mechanical Engineering for their support and valuable suggestions during this work.

I would also like to thank all the supporting staff of the Dept. of MECHANICAL and all other departments who have been helpful directly or indirectly in making the paper success.

I would like to express my high regards, sincere thanks and profound gratitude to all my family members specially my mother for their moral support and blessings.

IX. REFERENCES

[1] Thirupathi r. Chandrupatla & ashok d.belegundu ., introduction to finite eleement in engineering, pearson ,2003

[2] Joseph shigley, Charles mischike ., mechanical engineering design, tmh,2003

[3] Maithra ., handbook of gear design,2000 [4] V.b.bhandari., design of machine elements,tmh,2003 [5] R.s.khurmi ., machine design, schand,2005 [6] Darle w dudley.,hand book of practical gear

design,1954 [7] Alec strokes., high performance gear design,1970 [8] Www.matweb.com [9] Standards in spur and helical gears with FEM based

verification,” ASME Journal of Mechanical Design,Vol 128/114

[10] J.O.Nordiana, S.O.Ogbeide, N.N.Ehigiamusoe and F.I.Anyasi., 2007,”Computer aided design of a spur gear, “Journal of Engineering and Applied Sciences 2 (12); pp 17431747.


33

Stress Analysis and Damage tolerance evaluation for wing structure with a large cutout in the bottom skin

Balaji Pukale

PG Scholar

Department of Mechanical Engineering


Hyderabad, India

[email protected]

M.Amarnadha Reddy

Associate Professor & HOD



Hyderabad, India

[email protected]

Abstract— Wings are the lift generating components in the airframe structure. Wings are also used as fuel tanks in the transport aircraft. From the functional requirements point of view, cutouts are introduced in the bottom skin of the wing structure. Bottom skin is under tension stress field during flight. Cutouts in the bottom skin will act as stress risers due to stress concentration effect. The current project includes the stress analysis of a wing box with large cutouts in the bottom skin to identify the critical location for fatigue crack initiation. Damage tolerance evaluation includes the stress intensity factor calculations at crack tip. This is carried out by simulation of the crack in the finite element model. Stress intensity factor (SIF) at different crack lengths will be calculated using Modified Virtual Crack Closure Integral (MVCCI) method.

Keywords— Damage tolerance design, Transport airframe, Stiffened panel, Finite element analysis,Wing box,SIF, MVCCI method.

I. INTRODUCTION

Aircraft is a flying machine which flies in air. Aircraft means it is not only airplane it will be categorized in to airplane, helicopters, parachute, and lighter-than-air vehicles. There are many aspects of design of aircraft structures are available. For modern jet aircraft, the design must incorporate clear aerodynamics shapes for long range flight near or at supersonic speeds, and or wings to open up like parachutes at very low speeds. Safety and weight are two major considerations in aircraft design. There should not be any compromise between safety and weight. Aircraft is mainly subjected to drag force, lift force, thrust force and weight due to these loads there are mainly five types of stresses occurred which are tensile stress, compressive stress, bending stress, shear stress and torsion stress. Frames and stiffeners will help to carry these loads. An aircraft is

a complex structure, but a very efficient man-made flying machine.

The basic functions of an aircraft’s structure are to transmit and resist the applied loads to provide an aerodynamic shape and to protect passengers, payload systems, etc., from the environmental conditions encountered in flight. Airframe design is a field of engineering that combines aerodynamics, materials technology, and manufacturing methods to achieve balances of performance, reliability and cost. Aircrafts are generally built-up from the basic components of wings, fuselage, tail units and control surfaces. Each component has one or more specific functions and must be designed to ensure that it can carry out these functions safely. Any small failure of any of these components may lead to a catastrophic failure of material.

a) Material Selection

Selection of aircraft materials depend on the considerations which are categorized as structural performance and cost. The key material properties that are required to maintain cost and structural performance are,

Ultimate and Yield strengths

Damage tolerance (fracture toughness and crack growth)

Density

Young’s modulus

Fracture toughness

Thermal expansion

Fatigue strength

Corrosion


34

Based on the above considerations some other criteria associated with producing the basic materials in the form of requirement and fabricating the end product at a reasonable cost. They are

Material cost

Availability

Fabrication characteristics

Airframe structural components are made of wide variety of materials based on their properties and requirement. The earliest aircrafts were constructed from wood. Now modified aircrafts are constructed from molded composite materials, such as carbon fiber. Structural members of an aircraft’s fuselage include bulkheads, stringers, longerons, ribs, spars and more. The skin of aircraft is made from a variety of materials, ranging from impregnated fabric to plywood, aluminum, or composites. Under the skin and attached to the structural fuselage are the many components that support airframe function. The entire airframe and its components are joined by rivets, bolts, screws, and other fasteners. Welding, adhesives and special bonding techniques are also used.

Objective and Scope of the work

The main objective of this study is to evaluate the Stress analysis and Damage tolerance evaluation for wing structure with a large cutout in the bottom skin.

Stress analysis of the wing structure with a large cutout in the bottom skin using FEA methodology.

Refinement of the analysis model near the high stress region to capture the stress concentration and gradient stress field.

Calculation of stress intensity factor for different crack length in the stiffened panel.

Methodology

Stress analysis: Stress analysis is carried by Finite element method.

Software used: MSC Patron & MSC Nastran is a finite element analysis (FEA) program that was originally developed for NASA in the late 1960s under United States government funding for the Aerospace industry. The MacNeal-Schwendler Corporation (MSC) was one of the principal and original developers of the public domain NASTRAN code. NASTRAN source code is integrated in a number of different software packages, which are distributed by a range of companies.

Stress intensity factor calculation: SIF calculations carried by Modified Virtual Crack Closure Integral method (MVCCI).

II. PROBLEM FORMULATION

CAD modeling of the wing structure with a large cutout in the bottom skin is carried out using CATIA V5 tool. Stress analysis of stiffened panel with structure with a large cutout in the bottom skin is done by MSC PATRAN and NASTRAN for the internal pressurization load.

Scope of problem Statements

Steps used in MSC-Nastran and MSC-Patran is shown below

Fig: 1 Steps involved in problem formulation

Geometric modeling

A geometric model of the with a large cutout in the bottom skin is carried by CATIA V5 R20 with specified geometrical configuration available by using points, lines, surfaces and solids.

Finite Element Method

Elements, loads after the preparation of geometric model, it is imported in FEA software MSC-PATRAN and then extraction and meshing of model is done. After appropriate meshing using QUAD and TRIA and boundary conditions are applied at required locations of the model and then properties are defined to the various components and parts of fuselage structure and then analysis is done.

Solving

After running the analysis, the database file is imported in the solver MSC-NASTRAN software for the solving of the problem

Review

After solving the problem, the result file created by solver software is imported in MSC-PATRAN for reviewing the results. The results are carried out in the form of stress tensor over the whole structure and deformation of parts and full model.


35

Material Specification

Selection of aircraft materials depends on their properties which can be categorized on cost and structural performance. Mechanical properties of the skin, stiffening members and rivets are required for finite element models. There is little information on the material properties of skin, stiffening members and rivet material in the literature. Aluminum 2024 is used for components fuselage and rivet. Table 1 describes few material properties used for analysis.

Table 1 Material properties used for analysis

Material Property Aluminium-2024 T3

Ultimate tensile strength

483 MPa

Tensile yield strength

362 MPa

Young’s modulus 70000 MPa

Poisson’s ratio 0.33

Fracture toughness 98

Aluminum alloys are widely used in modern aircraft construction because of their material properties shown in table above. There are also different grade among them aluminum 2024 and 7075 alloys are most commonly used. The 2024 alloys T3 have good fracture toughness. T is the code number which indicates the heat treatment process. The 7075 alloys (7075-T6, T6510) have higher strength than the 2024 but lower fracture toughness. Fracture toughness is very important parameter.

III. STRESS ANALYSIS

The CAD model prepared in CATIA V5 is imported in MSC PATRAN FEM software and then each curve surfaces are extracted for further working processes. The wing structure with a large cutout in the bottom skin is divided into groups according to their properties. The meshing includes quad and tria (shell) elements with fine mesh is done in between cutout edges. Corse meshing is done wherever fine meshing is not required. The cutout is associated with rivet holes which are present in actual cutout of bottom skin structure. For the meshing in skin, shell elements especially QUAD elements are used with fine mesh size around the cutout because the chances of getting stress concentration near the cutout is very high and also coarse meshing is done with both QUAD and TRIA elements. Coarse meshing is done for stringers where QUAD elements are used. While meshing them, it should be in mind that the nodes of these elements must also match with the nodes of

skin where connectivity is achieved by 1-D bar element rivets. MPC (multi point constraint) is done for the rivets around the cutout which are used to apply more sophisticated constraints on the FEM model such as sliding boundary conditions.

Finite Elemnt Method of wing structure with large cutout at bottom skin

Meshing can be done using MSC-nastran and MSC-patran software. Fine meshing with 1mm elemental length is done around the cutout region. Course meshing is done away from the stress concentration region . Connectivity established between them by modifying the mesh.

Fig: 2 Finite element of wing structure

Table 2 Total no. of nodes and elements are used

Product Description

Types of Elements

No. of Elements

No. of Nodes

Bottom

Skin

QUAD4 11268

11708 TRAI3 121

Top Skin

QUAD4 5414 5579

TRAI3 7

Ribs & Spar

QUAD4 9680

11135 TRAI3 223

Stringers QUAD4 3880 4704

Rivet 1D bar 1530 2836

Loads and Boundary conditions


36

Fig: 3 shows load and boundary condition

Wing span =10.97m

Fuselage width=1.12m

Lift load /wing = 0.4*1362kg = 652.8kg

Total lift load/wing = 652.8*4.5 = 2937.6kg

L1 = 0.0895*2937.6 = 262.91

L2 = 0.1093*2937.6 = 321.07

L3 = 0.1243*2937.6 = 365.143

L4 = 0.1341*2937.6 = 393.93

L5 = 0.1391*2937.6 = 408.62

L6 = 0.134*2937.6 = 396.63

L7 = 0.12129*2937.6 = 356.301

L8 = 0.0895*2937.6 = 262.9152

L9 = 0.0398*2937.6 = 116.918

L10 = 0.0199*2937.6 = 58.458

Total Bending moment = 7009937.472kg-mm

MbTotal = 7*106 kg-mm

Bending moment = Force * Distance

Mb = F*D

F= 7*106/ 2800

F = 2503.54 kg

F/L = 2503.54/386 = 6.48 kg/mm

Deformation contour

Fig: 4 The deformation in wing structure

Maximum deflection at the tip was found to be 26.8 mm

Stress Contour

The maximum stress is found at the rivet hole location in the skin near the cutout region. Where the rivets are used to fasten the stiffeners on the skin. Fine mesh was carried out to capture gradient stress distribution

Fig: 5 Fig shows induced stress

Maximum stress was found near the rivet hole of fuel access cutout of magnitude 21.3 kg/mm2

IV. CALCULATIONS

SIF can be calculated by Modified Virtual Crack Closure Integral (MVCCI) method. SIF for 10 mm crack length is calculated by

Where,

K is the stress intensity factor in MPa√m

G is the strain energy release rate in N/mm

E is young’s modulus in N/mm2.

Strain energy release rate is calculated by

Where,

G is strain energy release rate


37

F is grid point force balance

ΔV is the crack opening displacement

Δa is the elemental edge length near the crack tip in mm,

T is the thickness in mm,

Fig: 6 Finite Element Models in The Vicinity Of a Crack Tip

The values of crack opening displacement and force at the crack tip are taken from F06 file after solving from software that is shown below. Displacement vector gives the values of crack displacement vector for node 679337is 0.3984 mm which is taken as V2 that is shown below. Where T1, T2, T3 are translations along X, Y, Z axis and R1, R2, R3 are the rotations about X,Y,Z axis respectively.

Fig: 7 (a) crack displacement vector for node 67933

Every node has 4 elements; force in two upper elements will be equal to lower elements but in opposite direction. So, two elements are considered for calculating SIF. Element 49551 has force of 73.32 which is F2. And element 47058 has force of 83.96 which is shown below.

Fig: 7 (b) Crack displacement vector for node 87492.

Fig: 7 (c) Force at tip of crack

Strain energy release rate is,

Elemental length,

Δa = 1 mm

Crack opening displacement,

ΔV = V1 –V2

= 0.3984 - 0.3511

= 0.0473 mm

Force at tip of crack,

F = F1+F2

= 73.32 + 83.96

= 157.28 Kg

Thickness, t = 2mm

Young’s modulus, E = 7000

Substituting these values in above equation,

Stress Intensity Factor is calculated by

Where,

G = 1.69 Kg/mm


38

E = 7000 kg/mm2

So,

K= 108.76 kg/mm² √mm

K = 108.76 9.81 10-3/2

K = 33.74 mpa√m.

V. RESULTS

SIF can be calculated for different incremental crack lengths ranging from 10 mm to 637 mm. SIF for different crack length is shown in table below.

Table: 3 Stress intensity factor values for different crack lengths of the stiffened panel

Fig: 8 SIF vs. crack length

VI. CONCLUSION

Damage tolerance design philosophy is generally used in the aircraft structural design to reduce the weight of the structure. The air load distribution was considered for the stress analysis of the wing structure. The crack is initiated from the location of maximum tensile stress. MVCCI method is used for calculation of stress intensity factor.FEM methodology is used for the stress analysis. A stiffened panel with a fuel access cutout was analyses with and without the presence of the crack. Variation of SIF is studied for different crack length. Plot indicates that SIF decreases near stiffener location. Residual strength calculation where carried out for different crack length. Residual strength plot indicates that the crack get arrested near the stiffener

location. Results obtained from the current study are in good comparison with results shown from an International journal paper.

VII. AKNOWLEDGMENT

First and foremost, I offer my sincere gratitude to my internal guide Mr. Mr. AMARANADH REDDY.M, Associatie Professor & HOD of Mechanical Engineering who has supported me throughout this project with her/his patience and valuable suggestions. I would like to thank Mr. Y.Dilip Kumar, PG (M.Tech) Coordinator for his valuable guidance and encouragement during my dissertation work I am also grateful to the Principal Dr. V.S.K. Reddy for providing me with all the resources in the college to make my project a success.

VIII. REFERENCES

[1] Newman, J. C., Jr., "Finite Element Analyses of Fatigue Crack Propagation -- Including the Effects of Crack Closure", Ph.D. Thesis, Virginia Polytechnic institute and State University, Blacksburg, VA, May 1974.

[2] Newman, J.C., Jr., “An Elastic-Plastic Finite Element Analysis of Crack Initiation, Stable Crack Growth, and Instability”, ASTM STP 833, 1984,

[3] W.T. Chow and S.N. Alturi, “Finite element calculations of stress intensity factors for interfacial crack using virtual crack closure integral”, Computational mechanics 16 (1995).

[4] G.I. Nesterenko, B.G. Nesterenko, “Ensuring structural damage tolerance of russian aircraft”, International Journal of Fatigue, pp. 1054–1061, 31 Jan 2009.

[5] Lucjan Witek , “stress intensity factor calculations for the compressor blade with half-elliptical surface crack using raju-newman solution” Fatigue of Aircraft Structures, Vol. 1, pp. 154-165, 2011.


39

Energy Audit: A Case Study to Reduce Lighting Cost

P.Srinivasa Kumar

Associate Professor


Malla Reddy College of Engineering & Technology

Hyderabad , Telangana , India

[email protected]

Absract----- An energy audit is an inspection, survey

and analysis of energy flow for energy conservation in a building or system to reduce the amount of energy input into the system without negatively affecting the outputs. Energy demand is an increasing pressure for any government. For the developing country like India, the energy generated decides the economic growth of the country. Being the fifth largest power generator and the fourth largest power consumer in the world, energy demand and scarcity rules the country. Energy demand in our country is increasing exponentially. Energy conservation can be the best solution for the raising energy demand. Lighting is an area, which provides a major scope to achieve energy efficiency at the design stage, by incorporation of modern energy efficient lamps, luminaries and gears, apart from good operational practices. This paper focuses on energy auditing by conducting a case study of mechanical engineering block2 of MRCET on conventional lighting loads and replacing with energy efficient lamps and comparing the results.

Keywords---- Energy Demand; Energy Audit in; Lighting Loads; Energy Conservation.

I. INTRODUCTION

The country's annual electricity generation

capacity has increased in last 20 years by about 120 GW, from about 66 GW in 1991 to over 100 GW in 2001, to over 185 GW in 2011[1]. Over 2010–11, India's industrial demand accounted for 35% of electrical power requirement, domestic household use accounted for 28%, agriculture 21%, commercial 9%, public lighting and other miscellaneous applications accounted for the rest. Energy conservation means reduction in energy consumption without making any sacrifice of quantity or quality. A successful energy management program begins with energy conservation; it will lead to adequate rating of equipments, using high efficiency equipment and change of habits which causes enormous wastages of energy. In spite of this, India currently suffers from a major shortage of electricity generation

capacity, even though it is the world's fourth largest energy consumer. Of the 1.4 billion people of the world who have no access to electricity in theworld, India accounts for over 300 million. As of January 2012, the per capita total consumption in India to be 778kWh [2].

II. ENERGY AUDITING

As per the Energy Conservation Act, 2001, Energy Audit is defined as "the verification, monitoring and analysis of useof energy including submission of technical report containing recommendations for improving energy efficiency with cost benefit analysis and an action plan to reduce energy consumption". Implementation of recommended measures can help consumes to achieve significant reduction in their energy consumption levels[3]. An energy audit is an inspection, survey and analysis of energy flow for energy conservation in a building or system to reduce the amount of energy input into the system without negatively affecting the outputs. The objective of this paper is to study the energy consumption of an educational building and reduce the consumption without affecting the output.The institutional building is considered here because of the uncontrolled and unpredictable usage of light,fans and airconditioning facilities in number of classrooms, practical rooms, auditoriums and also rooms with computer facilitiesand UPS[4].

Energy audit analysis in general order involves:

• Analysis of the energy consumable systems and the utility bills

• Survey about the condition of the system

• Understanding the need of the consumer

• Evaluating the possible energy conservation measures and

• Estimating the energy savings potential.

Studies and researchers have shown that energy auditing and conservation in India can save


40

approximately Rs.1800 crores per year as there is a big potential for saving energy in industrial sector and save installation equivalent to 5250 MW.

III. METHODS OF ENERGY AUDITING

Energy audits can be carried outs in different ways. Depending on time span invested auditing can be classified in as:

i) Walk Through Audit

ii) Intermediate Audit

iii) Detailed / Comprehensive Audi

i) Walk Through Audit

This is simple kind of energy, it carries rapid survey of plant. During rapid walk survey main focus is on the energy input, spots of energy wastages and ECO’s. Data about plant is collected in such a way that, data should be utilized for next detailed audits. Usually audit is carried out at two periods viz. During off period & during working shifts Generally this kind of audit is carried out for three days to one week. As the time span required is short cost involve in auditing is also less.

ii) Intermediate Audit

This kind of audit is conducted for detailed survey and measurement of systems compare with walk through audit. Major focus is made on energy loses measure and quantification to analyze energy efficiency of system. Generally low tech recommendations are preferred with first preference is given for -Switching off lights and fans when not required. -Placing of automatic thermostat to control temperature of water heaters etc -Spotting out golden ECO’s which involves higher energy wastage cost. This type of audit is carried out for one week to one week; time span required is more so the cost associated with audit is also more compare with walk through audit.

iii) Detailed / Comprehensive Audit

This is exhaustive audit than the previous types of audit. Detailed survey of systems as well as subsystems of an industry is done. Energy consumption of all subsystems and systems is compared with targeted energy consumption. This kind of audit also identifies the consumption of secondary energy like electricity, steam, gases etc.

Modernization and changes in major retrofitting as suggested if required.

MEASURES IN ENERGY AUDITING OF

EDUCATIONAL BUILDING

An educational building is selected for the energy auditing due to the fact that the number of people involved in an educational building is huge and the possibility of energy conservation is more. Lighting load is where most of the energy is wasted than consumed. In any educational building, lighting load consumes more than 20% of the total electrical energy consumption. Replacing the regular tube lights employingelectromagnetic ballast with Compact Florescent Lights (CFLs) and Light Emitting Diodes (LEDs) is discussed in the paper.

IV. ESTIMATION OF LIGHTING LOADS

Block 2 of MRCET consists of Mechanical engineering, Mining Engineering and Aeronautical Engineering departments,lighting loads of all these departments are considered for calculating lighting load.

Several places are identified during the audit, as the place for easy and efficient energy savings. A count on lighting is done after proper identification and calculation about the replacement of the light as it should not affect the consumers need. In the analysis, the energy consumption of tube lights along with ceiling fixture lights, CFLs and LEDs are evaluated and compared.

Florescent tubes: The usage of 40 W tube light and ceiling tube fixture each 14X4W consumes the specified energy: Total number of tube lights being 308,total energy consumed by the tube lights is (128X40)*1+ (14X180)*1 = 7.64 kWhour. Assuming 7 working hours a day and 22 working days per month, total energy consumption by the tube lights are 7.640*7*22=1176.56 kWh. The cost wise comparison is also done assuming Rs.6.00 per unit. The total amount is 1176.56*6.00 = Rs. 7059.36 per month.

CFLs: Replacing the 40W tube lights with 12 watts CFLs [5], total energy consumed by 128+180= 308 CFLs is, 308*12*1 =3.696 kWhour. Assuming7 working hours a day and 22 working days per month, total energy consumed by the CFLs are3.696*7*22=569.184kWh. The cost wise comparison is also done assuming


41

Rs.6.00 per unit. The total amount is 569.184*6.00 = Rs. 3415.10 per month[6] .

LEDs: Replacing the 40W tube lights with 5 watts LEDs [7], total energy consumed by 128+180=308 LEDs are, 308 *5*1=1.54 kW hour. Assuming 7 working hours a day and 22 working days per month, total energy consumed by the LEDs is 1.54*7*22=237.16 KWh. The cost wise comparison is also done assuming Rs.6.00 per unit. The total amount is237.16*6.00= Rs. 1422.96.

Fig 1. Shows the energy consumption comparison between tube lights along with ceiling fixture lights, CFL and LED.

1176.56

569.184

237.16

00

200

400

600

800

1000

1200

1400Comparison of kWh/month

FIG-1: COMPARISON OF KWH/ MONTH

Fig.2. shows the comparison of cost/unit consumed between tube light, CFL and LED.

FIG-2: COMPARISON OF TOTAL COST OF ENERGY/MONTH

The table 1 below shows the cost wise comparison between the tube light, CFL and LED

TABLE 1. COST COMPARISON BETWEEN TUBE LIGHT, CFL AND LED

Details of bulbs

Tube lights

CFL LED

Number of bulbs

308 308 308

Watt per bulb

40 12 5

Cost per bulb

Rs 45 &small FL@ Rs 26 each

140 Rs 250

Cost of 308bulbs (initial

investment)

Rs10440 Rs43120 Rs77000

kWh energy

consumed by the bulbs

7.64kWh 3.696kWh 1.54kWh

Cost of energy

consumed at Rs.6 /kWh

Rs 45.84 Rs22.176 Rs 9.24

kWh energy

consumed per month (assuming 7working

1176.56 kWh

569.184 kWh

237.16 kWh


42

hours and 22 working

days)

Cost of energy

consumed per month

Rs7059.36 Rs.

3415.10 Rs.

1422.96

The the life span of a LED is generally 50,000 hours which is approximately 40 times more than the life span of tube light and 5 times more than the life span of CFL[8]. The pay back from the CFL and LED is more than the tube light as the energy consumed by the CFL and LED is less when compared with tube light.

V. CONCLUSION

It shows that replacing the conventional tube lights with energy saving CFLs or LEDs reduces the energy consumption drastically. In addition to this the CO2 emission is also reduced when the tube lights are replaced.Replacing a single tube light with a CFL will keep a half-ton of CO2 out of the atmosphere over the life of the bulb [9].A simple change in system can conserve energy and bring down the utility bill amount to a greater extent.Energy audit in all the sectors with few changes in the existing system can conserve energy, which in turn will reduce the power demands in our country. The government can decide policies to initiate the energy audit which will make a great change in the economical status of India in the global market.

VI. RECOMMENDATIONS

Setting timers for air conditioning units, installing automated sensor based fans and lights, replacing the copper ballast of the tube lights with electronic ballasts can reduce the energy consumption.

Using the computer, one of the widely used machine, at the optimum brightness level, which is 15 to 30 percentage in each LCD monitors, can reduce power drawn by three to five watts per computer.

The tubes not required during day time should be switched off and better arrangements for use of natural daylight should be made.

Replace incandescent lights in exit signs with LED fixtures, which can reduce costs of these signs by up to 95 percent[10]

Using energy efficient compact fluorescent bulbs especially in fixturesthat operate more than two hours a day. They cost more initially but use 75 percent less electricity and last about ten

times longer than incandescent bulbs.

Use long-life bulbs only in hardto-reach places. Selecting bulbs carefully; looking for the highest lumens at the lowest wattage..Keep light fixtures clean to gain the most illumination.Cleaning the lamps & fixtures regularly; Illumination levels fall by 20-30% due to collection of dust. Switching of thelights when they are not in use. Photo sensors to be installedin department to utilize optimum day lighting. There areseveral types of sensors available in the market at affordableprices with the help of which we can save a plenty amountof energy.

Natural lighting can be considered for corridor.

VII. REFERENCES

[1] “All India Regionwise Generating Installed Capacity of Power” – Central Electricity Authority, Government of India [Online],2014.

[2] “Electricity Sectors of India” [Online] 2013, [3] ”Auditing transactions” [Online] 2013 [4] “Energy Audit” [Online] 2013, [5] “Pick a CFL”

[Online] 2013 [5] “CFL bulb comparison” [Online] 2013 [6] “Energy Efficient bulb” [Online] 2013 [7] Malkiat Singh, Gurpreet Singh, Harmandeep Singh

“Energy audit: A case study to reduce lighting cost” AJCSIT, Volume 2, No.5, 2012

[8] “CFL replacement with tube light” [Online] 2012, Available:http://www.bijlibachao.com/lights/are-cfls-replacements-for-tube-lights.html.

[9] “Energy Saving Tips” [Online] 2012.


43

Thermoelectric Power Generation from Biomass Cook Stove: A Waste Heat to Energy Conversion

D.Damodara Reddy Makena Harish

Associate Professor Assistant Professor

Department of Mechanical Engineering Department of Mechanical Engineering

Malla Reddy College of Engineering & Technology Malla Reddy College of Engineering & Technolog

Hyderabad, Telangana, India. Hyderabad, Telangana, India.

M. Amarnadh Reddy

HOD, Associate Professor


Malla Reddy College of Engineering & Technology

Hyderabad, Telangana, India

Abstract-This paper point out the present cooking

conditions of rural India and provide a better option for cooking stove for off grid rural areas. The traditional biomass cook stove is associated with number of disadvantages like low efficiency, huge emissions of toxic gases like CO, risks of getting burn. To improve the efficiency of a traditional cook stove it is necessary to provide sufficient air inside the combustion chamber to increase the air-fuel ratio and to achieve complete combustion. For such requirements, mostly improved cook stoves are attached with a small fan. The fan is usually run by electricity or a battery. Most of the rural households do not have access to electricity, so the concept of fan driven improved cook stove fails in those areas. To run a fan off grid, the waste heat from the cook stove is utilized to convert into electricity with the help of a thermoelectric generator. The waste heat of the cook stove is utilized for heating one side of the thermoelectric generator and the other side of thermoelectric generator is cooled by natural or forced convection of air to generate sufficient amount of energy to power a fan for the cook stove. The power generated can also be used for lighting and charging mobile phone.

Keywords-Thermoelectric power generator; Module; TE module; Seebeck cells; Thermoelectricity; Biomass stove; Thermal Energy

I. INTRODUCTION

Biomass is the primary fuel for cooking in rural areas of India. People still rely on natural resources like wood, cow dung, agricultural waste as fuel and built the cook stove with bricks and clay, which gives an investment free cooking. Due to lower efficiency of traditional cook

stoves, it results in inefficient use of scarce fuel-wood supplies. Deforestation is increasing in a very alarming rate which is resulting in environmental disturbance. Traditional cook stoves also results in high emissions of air pollutants and the smoke emanating from these cook stoves also causes acute respiratory infection (ARI). In rural household, still people use traditional three stone cook stoves made of brick and clay and biomass/wood as fuel. Most of the houses are without electricity. Only a fraction of the houses in typical “electrified”. Few Indian villages have acquired domestic connections for electric lighting; the remaining houses depend on kerosene lamps and candles. In India energy consumption per capita is 631 kWh and the average power per capita (watts per person) is 50.5W which is very low as compared to developed countries. In rural India 400 million (57% of population) is without access to electricity. The cook stove that is presented can provide 5-10W to cover basic needs of the people such as lighting and mobile charging to the low income populations living mostly in rural areas. The TEG modules integrated with cook stove are an essential and interesting option to provide electricity. The aim is to study the feasibility of using TEG in the existing or new cook stove for generation of electricity. The expected power generation from the TEG is 5-10W to run a fan for complete combustion and also for basic needs like lighting, radio and charging cell phones as well as other small electronic devices. Hence, such cook stove can be equipped with a thermoelectric generator either in chimney or in the body of cook stove, which can be fed with hot flue gases from cook stove and ambient and can create the temperature difference.


44

II. PRINCIPLE

The principle behind TEG is to convert waste heat as heat source into electricity, which is regarded as totally green technology since the input energy is totally free of cost, and the output of the of the TEG module is of high importance due to its power generating feature and making the cook stove economically viable. On the advent of semiconductor material science the thermoelectric generation practical applications got high emphasis of conversion of waste heat into electricity. The features like reliability and ruggedness of semiconductor material that came from solid state function has made this technology more viable and useful.

Fig.1. Thermo Electric Generator

In 1821, Thomas J. Seebeck discovered that a potential difference could be produced by a circuit made from two dissimilar wires when one of the junctions was heated. This is called Seebeck effect. The emf is proportional to the temperature difference. The potential difference V = αΔT, where, ΔT = Tc and α is the Seebeck coefficient or thermopower expressed in and the sign of α is positive if emf tends to drive an electric current through wire A from the hot to cold junction. The components of thermoelectric modules comprise of two different semiconductor materials also known as Seebeck cells or thermo elements. The TEG module has many semiconductors thermoelements connected electrically in series to elevate the resulting voltage and due to the temperature difference between the walls of the plate energy is captured from thermally excited electrons. A single thermocouple comprises of two thermoelement, p-type and n-type. The themoelements of the n and p-semiconductors are connected thermally in parallel and electrically in series. After thirteen years of Seebeck effect discovery J .Peltier observed the second thermoelectric effect known as Peltier effect. According to Peltier effect the passage of an electric current through a thermocouple produces a small heating or cooling effect depending on its direction. The interdependency between Seebeck effect and Peltier effect was determined by W .Thomson later known as Thomson effect consists of reversible heating or cooling when there is both a flow of electric current and a temperature gradient.

Fig.2. Schematic Diagram of TEG

III. THEORETICAL MODELLING OF TEG

The electrical resistance R and thermal conductance K of a thermocouple of length L and cross-sectional area Ap are defined respectively as

(1)

(2)

The equations used to model the behavior of TEGs are based on the Seebeck, Fourier and Joule effects. Using the standard model and assuming one dimensional conduction through the module, the rate of heat supply QH and heat removal QC can be estimated at the hot and cold junctions as

(3)

(4)

Where ap,n is equal to (ap–an), and I is the current through the thermocouple. The electrical power generated by the TEG is given by the voltage and current across the external load, RL. By applying an energy balance across the module, the electrical power, Pelec, is equal to the difference between heat delivered and dissipated, or (QH _ QC).

(5)

Dividing across by the current gives the voltage:


45

(6)

This gives voltage as a function of current for a given temperature difference. Using the standard model, the parameter apn is measured by open-circuiting (I = 0) the TEG, and measuring the applied temperature difference and corresponding voltage. By setting Pelec equal to I2RL in Eq. (5), the current can be found from

Figure 3 to be inserted

Fig. 3. Diagram of a single thermoelectric thermocouple.

(7)

Substituting Eq. (7) into Eq. (5) yields an expression for the electrical power:

(8)

A thermoelectric module generates maximum power when the module resistance matches the load resistance, i.e.

when RL = R

It follows that maximum power, Pmax, is given by

(9)

From Eqs. (8) and (9), the power produced by each thermocouple is approximately proportional to its cross-sectional area, and inversely proportional to its length.

Therefore, power produced by an entire module is dependent on the number of couples N as well as the ratio of the load resistance to that of the TEG itself. Rowe and Min developed a theoretical model which also took into account the thermal and electrical contact resistances across the ceramic and conductive strips, but this model requires detailed knowledge of the contact parameters and the physical properties of the p–n pellets – information that is not always available from

the manufacturer or supplier. For this study, an approach used by Hsu et al. is utilized. This method, known as the effective Seebeck coefficient model, calculates the Seebeck coefficient under actual load conditions. This is necessary since the TEG performs differently under open-circuit and load settings. To calculate the effective Seebeck coefficient a fixed temperature difference is applied across the TEG and the load resistance is varied. For the TEG used in this study, Fig. 4 plots the voltage vs. the current for a range of temperature differences. A linear relationship exists between the voltage and current. The ‘effective’ open-circuit voltage for each DT can be read from Fig. 4 by extrapolating the voltage corresponding to zero current (y-axis intercept). Similar to Eq. (6), the approach of Hsu et al. relates the voltage to the current:

Fig. 4. Voltage vs. current for different DT for TEG

(10)

For the open-circuit voltage (I = 0), ADT has a maximum value in which A can be defined as the effective Seebeck coefficient, aeff.

(11)

The effective Seebeck coefficient specifies the TEG behavior under actual load conditions, indirectly taking into account the contact effects such as interfacial temperature drops which are not measured in this study. This results in a Seebeck coefficient of lesser magnitude


46

than the theoretical value for a given thermocouple. The power may be calculated from the following equation:

(12)

Peltier module was selected to work as generator. The heat input at the hot side is 200˚C and cold side of 30˚C. It was observed that the open circuit voltage at required is 2.5 V but the current output is 220mA. Since the power output of the Peltier module is very low, a TE power generator is considered for the required operation. A 14 W module HZ-14 was taken for testing in an external environment. The external environment was made with a heater of temperature 600˚C which complements the temperature inside the cook stove. The module works on continuous 250˚C on hot side. The hot side temperature may extend upto 360˚C and intermittent 400˚C. The cold side temperature is to be maintained to 50˚C to get maximum power output from the module. The hot side is attached with 7 x 7 x 2 cm3 thick aluminium block.

The cold side is properly insulated with glass wool so that the radiation heat does not affect the temperature on the cold side. The temperatures on the hot side and the cold side were recorded continuously with K-type thermocouples. The aim of the experiment was to check the module performance by providing desired temperature difference. The first experiment was performed in ambient condition. The second experiment was done by forced air cooling using a fan mounted in top of the sink. It is observed that the power output of the HZ-14 module is very high as, but the individual voltage and current output was not sufficient as per our requirement. The voltage output of the HZ-14 is quite low and the current is very high. Hence, the HZ-9, a 9W TEG module was selected for prototype development. This module has a Voc(max) of 6.5V. The module was considered appropriate since it is relatively easier to boost the voltage where we get output voltage soon. The arrangement of TEG for running a fan of 5V is given in fig 5.

Fig.5. Circuit Diagram TEG arrangement

IV. CONCLUSION

This study describes the design of an energy efficient biomass cook stove for developing countries to accomplish the requirement for both, cook stoves itself and electricity generation. For a simple and low cost application of a rural cook stove, commercially available thermo electric modules are tested and the suitable module is determined for selection. The best power output of the system depends upon the difference in temperatures, through both sides of thermo electric module. A particular attention must be paid to the design of the heat exchangers for heat plate and cold sink. An idea about various parameters associated with the cook stove and TEG module can be viewed with the help of results represented in above graphs. This study shows how that the TE modules can be a used in cook stove in convenient way. In this scenario the best generator module is required but the heat exchanger can be manufactured and assembled in a local workshop. The voltage generated from the modules practically is small due to inability to maintain the temperature difference, hence a dc-dc converter have to be connected to boost output upto the required voltage. The produced electricity will run the fan of the cook stove to increase the combustion efficiency. Thus it will decrease the fuel consumption and the emission level. Extra electricity generated can also be utilized to power up LEDs or charging a mobile phone.

V. REFERENCES

[1] WHO. Fact sheet No. 292: indoor air pollution and health; 2011.

[2] WHO. Global health risks: mortality and burden of disease attributable to selected major risks; 2009.

[3] Rowe DM, Min G. Design theory of thermoelectric modules for electrical power generation. IEE Proc Sci Meas Technol 1996;143:351–6.

[4] Hsu CT, Huang GY, Chu HS, Yu B, Yao DJ. An effective Seebeck coefficient obtained by experimental results of a thermoelectric generator module. Appl Energy 2011;88:5173–9.

[5] Hodes M. On one-dimensional analysis of thermoelectric modules (TEMs).IEEE Trans Compon Packaging Technol 2005;28:218–29.

[6] Rowe DM. Thermoelectric power generation. Proc Inst Electr Eng1978;125(11R):1113–6.

[7] Rowe DM. Thermoelectric generators as alternative sources of low power.


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[8] Renew Energy 1994;5:1470–8 Nuwayhid RY, Shihadeh A, Ghaddar N. Development and testing of a domestic woodstove thermoelectric generator with natural convection cooling. Energy Convers Manage 2005;46:1631–43.

[9] Warwick H, Doig A. Smoke – the killer in the kitchen. London: ITDG Publishing; 2004. p. 11.

[10] The Women’s refugee commission. Sexual violence and firewood collection inDarfur; 2006. p. 40–1. Canadian medical association. Malawi health workers grapple

[11] Killander A, Bass JC. A stove-top generator for cold areas. In: Proceedings of the15th international conference on thermoelectrics; 1996 Mar 26–29; New York, USA. New York: IEEE; 1996.

[12] R.Y. Nuwayhid, D.M. Rowe, G. Min. Low cost stovetop thermoelectric generator for regions with unreliable electricity supply. Renewable Energy 28 (2003) 205–222


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Characterization of Light Weight Composite Panels for Table Tennis Table

Mohamad R.M Yasin Engineering Technology (Manufacturing), Faculty of Engineering Technology,

Universiti Malaysia Pahang, Pahang, Malaysia

[email protected]

Abstract: Light weight composite panels (LWCPs) have attracted interest in various applications such as in building and transportation sectors. However, their usage in constructing sports equipment has not been fully explored due to the novelty of the materials and, sometimes, cost or manufacturing issues. Although traditional table tennis tables (TTT) have shown consistent performance, but due to the weight of the materials, commonly medium density fibreboards (MDF) used, the table movability is often limited. In this study, various composite panels using wood veneers and fibre reinforced polymers as face sheets incorporating different core structures have been developed for the purpose of prototyping a full-size standard TTT. In order to comply with the international standard for such a piece of sports equipment, the effects of various material parameters on the coefficient of restitution have been investigated. Such parameters include the types of core material and configuration, the types of face sheet and its thickness. From the study, the composite surfaces have displayed better restitution properties, i.e. bounce of ball is better, compared to the veneer surfaces. The bounce behaviour of the ball is also much closer to that on the standard TTT made from MDF. The findings from this study have demonstrated the potential of using LWCPs for the construction of TTTs to improve the mobility of this sport without compromising the quality of play.

Keywords: Light weight composite panels, restitution, dynamic coefficient of friction

I. INTRODUCTION

The use of composite sandwich panel in sport

applications is growing rapidly because of the advantageous features such as high strength to weight ratio and low maintenance cost [1]. Table tennis is one of the mainstream sports that manipulate the composite technology, in which most commonly to make the table tennis bet. However, very little research has been undertaken into the development of a light weight, strong and competitive table tennis surface from laminated veneer lumber (LVL) composite panel (plywood), fibreglass and foam. Plywood is a man-made composite combining natural and synthetic material. Thin layers of wood veneer are bonded together with adhesive to form flat sheets of laminated wood that are

stronger than natural wood [2]. Pine is one of the favoured plywood materials as it is easy to saw, treat, nail and glued [3].

The most common material of table tennis table is high density fibre (HDF) and high density press board (HDPB). Radiata pine wood veneer is thought to be a good alternative due to its low density (460 – 560 kg/m3) as compared to HDF and HDPB (between 800 – 1040 kg/m3) [5]. The main issue that comes along with Radiata pine is its relatively high equilibrium moisture content (EMC) compared to HDF and HDPB. HDF and HDPB have an EMC of 10.9% at 80% relative humidity [6]. This is relatively low when compared to the EMC of the untreated pine at around 16% [7]. However, the hygroscopic of wood, defined as the trait of the wood ability to absorb and desorb moisture depending on the humidity of the environment compared to the wood moisture content (MC), can be minimised when wood is heat-treated [8]. Heat-treatment recommended is done with dry air at temperature of 230 degrees for 2 hours for the decrease in physical properties such as shrinkage, swelling and EMC [9].

This research attempts to compare the performance of the prototyped sandwich panel developed with new types of sandwich panel of different core configuration and different types of face sheet. The effect on the panel restitution has been investigated for different core configurations, using honey comb, foam and combination of these two; as well as different face sheets, using wood veneer, two layers and three layers fibreglass. Fibreglass is a fibre-reinforced composite made of a plastic matrix reinforced by fine fibers of glass. Fibreglass is a lightweight, extremely strong stiff material, with Young’s Modulus of around 17.2 GPa [10]. Stiffness of the skin is thought to influence the restitution property of a sandwich panel. Fibreglass also exhibits very low moisture absorption, with the moisture content of almost 0% [11]. Meanwhile foam is a strong, lightweight material that is widely employed as the core material in sandwich structure due to its isotropic property hence providing more uniform property across the panel [12]. This will reduce the variability of the result from the restitution test. However, it is likely that impact loaded sandwich structures will absorb


49

significant energy in contact deformations local to the point of impact [13]. Therefore it is of an interest to study how this energy dissipation will effect on the restitution property of the sandwich panel constructed with foam as the core.

II. EXPERIMENTAL DETAILS

Two main variables being assessed are the cores and the face sheets of the panels. Four types of panels with different cores but the same face sheets (3 Plies Veneer) were manufactured to see the effect of the cores on the properties of the panels, while three different kinds of panels of different face sheets but the same core (honeycomb) were constructed to investigate the face sheet effect on the properties of the panels. 6 types of panels were manufactured to look at the effect of various parameters on the properties of the panels as shown in Table 1. All the panels have a same size (300x200mm) and thickness of 40mm.

Table 1: Manufactured Panel

Panel Core Type Face Sheet Type

1 Honeycomb 3 Plies Veneer

2 Foam 3 Plies Veneer

3 Combination of honeycomb and foam,

honeycomb on top

3 Plies Veneer

4 Combination of honeycomb and foam,

foam on top

3 Plies Veneer

5 Honeycomb 2-Layers Fibreglass

6 Honeycomb 2-Layers Fibreglass

Untrimmed 3 plies Radiata pine veneer sheets of size 2450 mm by 1250 mm were used to manufacture the honeycomb cores. The sheets were preglued with the stacking sequence of [0/90/0] to decrease the probability of warping during the thermoforming process, as corrugated sheet with grain directions normal to the corrugation direction tends to have lower bending stiffness and easily warped [8].

Veneer Honeycomb Panel

Using thermo-forming process, veneer sheets were formed into corrugations with dimension as shown in Figure 1 (reproduced from [14]) to be used as the core of the panels. To make honeycomb structure, the corrugated sheets were trimmed to 40 mm strips. These strips were glued between the peaks by crosslink PVA and clamped together under the pressure for 24 hours during curing. Once the honeycomb was within acceptable tolerance (1 mm), cross-link PVA was applied to the sides of the face sheet to create a bond at the intersection of the face sheet and the honeycomb core. Borders were added to the panel sides to provide more stability by reinforcing weak supports around the edges.

Foam Core Panel

The foam used was M80 Corecell MFoam supplied by SP-High Modulus ™ with the density of 81 – 89 kg/m3 and the thickness of 38 - 40 mm [10]. The foam was carefully cut to 300 mm by 200 mm. Cross-link PVA was applied to both sides of the foam fitted with 3 plies veneer face sheet to create a strong bond between the surfaces of foam and the face sheets and left to fully cured under load. Borders were added to the panel sides and the panels protruding features and sharp corners were sanded flush.

Combination of Honeycomb and Foam Core Panel

To make the core with a combination of honeycomb and foam, each honeycomb and foam was manufactured separately earlier. The procedures of manufacturing the honeycomb and foam core parts are similar to the one used to make the honeycomb and foam core panel. However, the thickness was halved to be 20 mm instead of 40 mm. Once the honeycomb and foam were readied, they were combined together by using the cross-link PVA to form a combined honeycomb-foam core panel of thickness 40 mm. Similar to other panels, 3 plies veneer face sheets were applied with cross-linked PVA to both

Figure 1: Corrugation dimension


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the refined honeycomb and foam core at regions of contacts and cured under evenly distributed loads and borders were glued to the panel sides to provide more stability by reinforcing weak supports around the edges.

Fibreglass Face Sheet Panel

The fibreglass face sheets were manufactured using the resin infusion technique. High clamping pressure of the vacuum (approximately 1 ton/sq.ft.) helps to fuse the material together with any air voids being replaced by resin, therefore results in a weight saving of over 30% over traditional cored fibreglass laminate while improving its properties. Two thicknesses were produced, by using 2 layers and 3 layers of fibreglass fabric. The sandwich panels were made up of layers of EU450-1270, a unidirectional stitched fibreglass fabric with a density of 480 grams per square metre. The polymer matrix utilised during the experimental procedures for this project was epoxy thermosetting resin R300 which is characterised by low viscosity and low exotherm [16]. The resin was used in combination with a fast hardener at a ratio of 80% resin and 20% hardener. The hardener used was R310 Infusion. The resulting mixture permit a faster infusion rate by lowering the viscosity of the resin, hence permitting the resin mixture to infuse the glass fibre more quickly. This was especially favourable when the temperature in the infusion chamber was low.

III. PANEL CHARACTERISATION

International standards set up by ITTF were used as a guideline to characterise the panels. The required testing to get approved by ITTF is the restitution test. The tests were conducted using ITTF approved table tennis ball, Butterfly brand, which is 3 stars, a rating system used to describe the quality of a ball [17].

Restitution Testing

In order to get approved by the ITTF, a standard table tennis ball needs to display a rebound of within the range of 230 - 260 mm when it is dropped from a height of 300 mm. The consistency of the ball bounce is also assessed, where the difference of the maximum and minimum bounce height observed during the approval testing of at least 16 systematically chosen points must be less than 10mm [17]. There were 120 testing points on each panel,

placed in equal length between each other. The distance between the testing points in y-direction is 20 mm and the distance between the testing points in x-direction is 26 mm. Each of the testing point restitution property was tested by dropping the table tennis ball from a fixed height of 300 mm. The bouncing motion of the ball was recorded with a high speed digital camera that captures 60 frames per second of the motion to determine the maximum rebound height. The measured maximum height of rebound was measured at the bottom-most side of the ball at its maximum height. For all the testing panels, each testing point was tested once and the result was recorded. 10 random testing points on each panel was selected to validate the consistency of the rebound height. This is done by repeating the test for five times at each point and the average was recorded.

IV. RESULTS AND DISCUSSION

Restitution Property

Restitution vs Type of Cores

The plots compare the restitution amplitudes based on different types of core, which are honeycomb, foam and the combination of both honeycomb and foam with both sided being tested. From the result in Figure 2, it is apparent that the 40 mm honeycomb core panel has the highest restitution with an average of 227 mm, while the foam core panel has the lowest restitution with an average of 220 mm. This suggests that the foam core gives more damping effect to the bounce of the table tennis ball as compared to the honeycomb core. However, the foam core panel has smaller spread compared to the honeycomb core panel. This is expected as the foam has a very uniform surface in contact with the face sheet, therefore the effect on the restitution is also uniform throughout the panel. The geometry of honeycomb core in the other hand gives supported and unsupported region underneath the face sheet, hence create variation in the restitution property throughout the panel. Meanwhile, the combination of foam and honeycomb core panel exhibits a restitution property in between that of honeycomb core and foam core. The combined core panel does not show much variation in terms of the average amplitude when honeycomb or foam were put as the panel top. However, the spread by the panel when foam was placed as the panel top shows slight reduction, suggesting that the foam contributes an effect in giving a more uniform restitution throughout the panel. This is expected due to the surface of the foam being much more uniform compared to the honeycomb core.


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Matlab code was generated to create a surface plot of the restitution over the tested panel area. Taking the length as the X-axis and Width as the Y-axis, the (0mm, 0mm), (0mm, 300mm), (200mm, 0mm) and (200mm, 300mm) coordinates represent the corner of the panel while (100mm, 150mm) coordinate represents the middle of the top of the panel.

Figure 3: Variation of restitution amplitude based for different types of core

From the surface plots in Figure 3, the variation of restitution amplitude is more noticeable for the panels with honeycomb core. This strengthens the deduction made earlier that the geometry of the honeycomb structure creates the variation in the restitution property. There is also a noticeable increasing trend in the restitution amplitude as it approaches the centre for all panels being compared above. This concludes that all the panels has a high reliance on the core configuration and the mechanical properties of the panel, rather than the supporting structure, like the panel borders, and sub-structure, like the loads on the panels during the testing.

Restitution vs. Type of Face Sheet

From the previous comparison, an early conclusion can be drawn that the core with the best restitution bounce is the honeycomb. Hence in further testing, honeycomb core has been used in comparing the effect of different face sheet to the restitution property. In this comparison, face sheets were varied by using 3 plies veneer face

Figure 2: Bounce vs Type of Cores of LWCP


52

sheet, 2 layers fibreglass face sheet and 3 layers fibreglass face sheet.

From the plots in Figure 4, the average restitution amplitude for the panel with two layers fibreglass face sheet does not vary much with the 3 plies veneer face sheet panel. This suggests the local flexural stiffness of the two layers face sheet is nearly the same as the 3 plies veneer face sheet. However, there is a noticeable increase in the restitution property for the three layers fibreglass face sheet panel. This is thought due to the three layers fibreglass face sheet having a higher global flexural stiffness therefore contributing to a higher bouncing of the table tennis ball.

Figure 5: Variation of Restitution Amplitudes for different types of face sheet

From the Matlab 3-D surface plots in Figure 5, there was significant variation in the restitution property of both fibreglass face sheet panels, as compared to the 3 plies veneer face sheet panel. A factor that could contribute to this is that the presence of the fibre may affect the restitution at a local testing point, while the fibre presence or the local percentage of fibre can vary between the testing points [18]. This could also be the contributing factor as to why the 2 layers fibreglass result is relatively less varied than its 3 layers fibreglass counterpart. This also suggests that the restitution on the fibreglass face sheet is heavily dependent on the face sheet configuration rather than the core.

Industrial Feasibility Study

Weight Comparison

Table 2: Weight comparison among the manufactured panel

Panel Core Face Sheet Weight

(per panel)

Density

(kg/m3)


482.0 g 200.8


411.0 g 171.3

3 Combination Honeycomb and Foam

3 Plies Veneer

513.5 g 214.0

4 Honeycomb 2 Layers Fibreglass

431.0 g 179.6


511.0 g 212.9

Figure 4: Bounce vs Face Sheet Type of LWCP


53

From the weight comparison shown in Table 2, the panel with combination of honeycomb and foam core has the highest density, due to the use of extensive amount of cross-link PVA in the manufacturing of the panel as compared to the other panels. Meanwhile the foam core panel has the lowest density, due to the lightweight and porous nature of the foam structure. Typically, the density of hardboard ranging between 800 - 1040 kg/m3 and the MDF is approximately 500 kg/m3 [5]. Therefore, the weight saving of the panels ranges between 70% and 80% compared to hardboard and up to 65% compared to MDF.

Operation Time Comparison

Table 3: Operation time comparison among the manufactured panel

Panel Core Face Sheet Operation Time

(per panel)


100 minutes


35 minutes

3 Combination Honeycomb and Foam

3 Plies Veneer

125 minutes


230 minutes


230 minutes

The panels with fibreglass face sheets equally took the longest operational time to be manufactured (230 minutes), while the panel with foam as the core consumed the shortest time (35 minutes). Meanwhile, honeycomb core panel took a moderate operational time (100 minutes) and the panel with core of honeycomb and foam combination took slightly longer time than that (125 minutes). The resin infusion process to make fibreglass face sheet is a complicated process, time consuming and is the biggest fraction of time taken to manufacture. If fibreglass sheets were to be used to manufacture the table tennis table in a mass production, it will require very high labour cost, as the labour needs to be skilful and working for a long hour. Although the fibreglass yields a better restitution property, fibre glass also has an exceptionally high strength, which is an unnecessary aspect for a table tennis table. Therefore, it can be deduced that using fibreglass is not feasible to be

manufactured as the table tennis table in mass production. 3 plies veneer sheet made of honeycomb core can be used to manufacture the table tennis table due to its low manufacturing time, its easiness to prepare and acceptable restitution property.

V. CONCLUSION

In comparison of different cores while keeping the face sheets to be 3 plies wood veneers, the 40 mm honeycomb core panel has the highest restitution, while the foam core panel has the lowest restitution. The foam core panel has smaller spread compared to the honeycomb core panel due to the foam has a very uniform surface in contact with the face sheet. The combination of foam and honeycomb core panel exhibits a restitution property in between that of honeycomb core and foam core. The combined core panel does not show much variation in terms of the average amplitude when either honeycomb or foam were put as the panel top. However, the spread by the panel when foam was placed as the panel top shows slight reduction, suggesting that the foam contributes in giving a more uniform restitution throughout the panel.

In comparison of different face sheets while keeping the cores to be honeycomb cores, three layers fibreglass face sheet panel exhibits highest restitution profile, at the expense of consistency. Meanwhile, the average restitution amplitude for the panel with two layers fibreglass face sheet does not vary much with the 3 plies veneer face sheet panel. There was significant variation in the restitution profiles of both fibreglass face sheet panels as compared to the 3 plies veneer face sheet panel.

The panel with combination of honeycomb and foam core has the highest density, while the foam core panel has the lowest density. The honeycomb core panel has density in between that of these two aforementioned panels. The weight saving the panels give ranges between 70% and 80% when comparing to hardboard, and up to 65% when comparing to MDF.

The panels with fibreglass face sheets equally took the longest operational time, while the panel with foam as the core consumed the shortest operational time to manufacture. The honeycomb core panel operation time is in between that of these two panels. 40 mm honeycomb panel would be suitable for casual table tennis table and could be viable alternative for a competition tables with further research.


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VI. REFERENCES

[1] Jack R. Vinson, R. L. S. (2002). The Behavior of Structures Composed of Composite Materials, Second Edition. Solid Mechanics and Its Applications.

[2] Composite Industry Overview. Retrieved 24 May, 2012 from http://www.acmanet.org/professionals/index.cfm

[3] Radiata Pine Properties. Retrieved 24 May, 2012 from http://tenon.co.nz/radiatapine/properties.aspx

[4] Information Sheet Radiata Pine. Retrieved 24 May 2012 from http://www.nzwood.co.nz/images/uploads/file/Info%20Sheets%20Species/NZW13611%20Species-RadiataPine.pdf

[5] ANSI A208.2 MDF for Interior Applications. Gaithersburg, MD: Composite Panel Association. 2002. p. 3.

[6] NcNatt, J. (1974) Effects of equilibrium moisture content changes on hardboard properties. Forest Products Journal, 24, 29-35.

[7] Esteves, B. Domingoes, I. and Pereira, H. (2008) Pine wood modification by heat treatment in air. BioResources, 3, 142-154.

[8] Srinivasan, N. (2008) Forming of Woodfibre Composites and Veneer Sheets. PhD Thesis, University of Auckland.

[9] Ates, S. Akyildiz, M. and Ozdemir, H. (2009) Effects of heat treatment on Calabrian Pine (Pinus brutia Ten) wood. BioResources, 4, 1032-1043.

[10] Polyester Matrix Composite reinforced by glass fibres (Fiberglass). Retrieved 10 June 2012 from http://www.substech.com/dokuwiki/doku.php?id=polyester_matrix_composite_reinforced_by_glass_fibers_fiberglass

[11] J. Yao, G. Z. (2007). Water Absorption Behaviour and Its Influence on Properties of GRP Pipe. Journal of Composite Materials, 993-999.

[12] Akay, M. and R. Hanna (1990). A comparison of honeycomb-core and foam-core carbonfibre/epoxy sandwich panels. Composites 21(4): 325-331.

[13] Akil Hazizan, M. and W. J. Cantwell (2002). The low velocity impact response of foam-based sandwich structures. Composites Part B: Engineering 33(3): 193-204.

[14] Kavermann, S., Banerjee, S., Bhattacharyya, D. (2010) CACM, Mechanical properties of novel plywood based sandwich core materials, The University of Auckland.

[15] Corecell ™ MFoam data sheet (undated). SP Gurit High Modulus

[16] PRIME ™ 20LV Epoxy Infusion System (undated). SP Gurit High Modulus

[17] The Ball Technical Leaflet T3. Retrieved April 20, 2012 from

http://www.ittf.com/stories/pictures/T3_40mmBall.pdf

[18] Padaki, N. and Alagirusamy, R. (2008). Low velocity impact behavious of textile reinforced composites. Indian Journal of Fibre and Textile Research 33: 189-202.

INTERNATIONAL JOURNAL OF ENGINEERING … · petroleum hydrocarbon [1]. Power production by MFCs...

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