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The energy absorption due to low-velocity impact on non-hybrid and hybrid (Kevlar-K, carbon-C, and glass-G) fabric reinforced epoxy composite laminates were studied by conducting standard drop weight tests. The experimental energy absorption results were compared with finite element analysis results. Both values were in good agreement with a maximum variation of about 6%. Kevlar/epoxy (K/K/K) specimen recorded the highest energy absorption (18.67 J) followed by Kevlar specimen sandwiched with glass fabric in the middle layer (K/G/K) (17.24 J). Specimens consisting of glass or carbon layers in the middle, sandwiched by Kevlar layers at the top and bottom (K/G/K and K/C/K) exhibited better energy absorption compared with laminates consisting of all three fabric reinforcements (K/C/G (13.38 J), G/C/K (16.11 J) and C/G/K (16.04 J), respectively). Considering the cost of these composite laminates, K/G/K composite offers 21% reduction in material cost when compared to K/K/K specimen and also offered reasonably enhanced impact resistance and energy absorption as compared to other hybrid composites. Hence, this data may be useful for developing cost effective impact resistant components for defense (protective helmets and body armor) and aerospace (aircraft body components) sectors. The morphologicalstudy of the drop weight impact tests revealed that, delamination, fiber breakage, fiber splitting, and matrix cracking are the major damage mechanisms observed in the study. The cost was found to be a critical factor to compare between the different composites. © 2021 The Authors. Published by Elsevier B.V. This is an open access article under the CC

In this study, a methodology combining finite element analysis (FEA) and artificial neural network (ANN) through multilayer perceptron architecture was utilized to predict the impact resistance behavior of hybrid and non-hybrid fabric reinforced polymer (FRP) composites. A projectile at 250 m s−1 impact velocity was considered for the high velocity impact simulations. The Kevlar, carbon and glass fabric-based epoxy composites were modelled and the impact tests were performed through finite element simulations. The residual velocity results from FEA were used as training data for the ANN prediction. The ANN predicted results were in good agreement with FEA results with a maximum variation of about 6.6%. In terms of impact resistance, composite laminates with more Kevlar layers exhibited enhanced performance compared to other samples. Neat Kevlar/epoxy (K/K/K) exhibited the best impact resistance performance in terms of lowest residual velocity and highest energy absorption of 101.84 m s−1 and 222.86 J, respectively. Whereas, neat glass/epoxy (G/G/G) specimens registered the highest projectile residual velocity (165.13 m s−1) and lowest energy absorption (158.99 J) compared to all other specimens. 2-fabric sandwich composite K/G/K exhibited a low residual velocity of 115.27 m s−1 and high energy absorption of 218.53 J, which is the second best among all specimens. Comparatively, the 3-fabric hybrid composites registered intermediate impact resistance results lower than that of Kevlar rich specimens, but significantly higher than neat G/G/G composite, thus, proving the effectiveness of hybridization in enhancement of impact performance compared to neat glass composite. Overall, the chosen methodology yielded significantly accurate results for the prediction of impact behavior of FRP composites.

The multi-walled carbon nanotubes (MWCNTs) and the poly(acrylonitrile-co-butadiene-co-styrene) (ABS) granulates are dispersed in acetone separately using a magnetic stirrer followed by ultrasonication. Further, both the solutions were mixed with magnetic stirring followed by ultrasonication. Neat-ABS film, 0.25 wt%, 0.5 wt% and 1 wt% of MWCNT-ABS nanocomposite films of the average thickness of 140 µm are fabricated by the solution molding using a petri dish, followed by room temperature curing and further hot compression to maintain uniform thickness. The tensile properties, thermal stability, electrical conductivity, and EMSE of all films are investigated. The results indicate that the addition of MWCNTs to ABS enhanced the mechanical properties and electrical conductivity, thermal stability, and EMSE. The 0.25 wt% MWCNT-ABS nanocomposite films show attractive mechanical, electrical, thermal, and EMSE as compared to neat-ABS films. More than 0.25 wt% MWCNTs in the ABS matrix deteriorates the tensile strength. However, 0.5 wt% MWCNT-ABS nanocomposites exhibit better tensile strength, Young’s modulus, electrical conductivity, and EMSE than neat-ABS. In this research, we used a low quantity of MWCNTs and followed a one-time heating process in the entire fabrication, and produced MWCNT-ABS nanocomposite films with reasonable properties. Hence, this may be one of the options to produce nanocomposites suitable for EMS materials. We recommend that these films may be used as interlayers to develop an X-band range electromagnetic wave shielding material.

Multiwalled Carbon Nano Tube (MWCNT) filled glass fabric reinforced epoxy composites (MWCNT/GEC), and neat GEC were prepared by hand-lay-up followed by hot compression molding method. As per the ASTM standard, specimens were prepared and investigated the influence of the addition of MWCNTs on flammability properties of GEC through the UL-94 vertical flammability test and the limiting oxygen index (LOI) method. The thermal degradation was studied by thermogravimetric analysis (TGA). It was found that the GEC improved upon the thermal stability and fire-retardant properties due to the addition of MWCNTs. It was observed that the 0.3 wt.% MWCNTs-glass fabric reinforced epoxy composite (0.3MWCNT/GEC) exhibits better properties than neat GEC and 0.075 wt.% MWCNT-glass fabric reinforced epoxy composite (0.075MWCNT/GEC) and 0.15 wt.% MWCNT-glass fabric reinforced epoxy composites (0.15MWCNT/GEC). Hence, this material may be suitable for electrical devices and appliances based on the other required properties’ further fulfillment.

A study of high-velocity impact behavior of multi-layer nanopolymer composites has been one of the most exciting research topics in materials science and engineering. The material researchers and designers developed and investigated the behavior of advanced materials suitable for impact resistance. Background information and current research activity in the field of fiber-reinforced hybrid nanopolymer composites are briefly reviewed. The factors influencing the performance of the polymer composites and failure mechanisms when subjected to high- velocity impact are presented. The ballistic properties of some representative composite materials containing Carbon, Glass, Kevlar, and hybrid fabric reinforced with suitable nanophase are briefly discussed. The material characterization methods and test standards are highlighted. A systematic approach that facilitates the formulation and fabrication of application-specific, ballistic properties-centered, and tailor-made design of polymer nanocomposites helps the scientific community achieve the desired material sufficiency. Such information can have important implications in the design of more sophisticated systems for a wide range of applications

Natural fiber reinforced polymer composites have proved to be fit for use in several structural and functional applications. Jute fiber reinforced epoxy composites are one of the most preferred natural fiber-based polymer composites. The emerging need for high strength application while considering environmental sustainability and with the advent of bio-composites, the researchers, in recent times, started showing interest in incorporating the various bio-based resins in the composites. The present work thus aims at investigating the possibilities of making jute fiber reinforced epoxy composites with alkali-treated fibers and cashew nut shell liquid blended epoxy resins. The feasibility is tested through the mechanical properties, which is quantified using tensile strength and flexural strength. The modified matrix in the prepared composites is based on the variation in the weight percentage of cashew nut shell liquid (25 and 30%). The results indicate that it is possible to make better composites using the modified matrix and alkaline treated jute fibers as the mechanical properties outperform the jute fiber reinforced epoxy composites made using conventional epoxy resin and untreated jute fibers. The best amongst all the variants made, the one that proved to be the best JFRE composite is having alkaline treated fiber and blend 2, which exhibits an average tensile strength of 679 MPa, and flexural strength of 88.83 MPa.

This work endeavors to investigate thermomechanical performance of carbon fabric reinforced epoxy composite (CEC) with fillers – hexagonal boron nitride (h-BN) and molybdenum disulfide (MoS2). The filler of 2, 4, 6, and 8 Wt.% was dispersed precisely in the epoxy resin through magnetic stirring and ultrasonication, prepared the filler loaded CEC using vacuum bag technique and studied the composite behavior at an elevated temperature by dynamic mechanical analysis. The 6 Wt.% MoS2-CEC showed 70% enhancement of storage modulus since the filler in the epoxy networks increased the composite stiffness. The increase in G-band intensity of Raman spectra in the filler loaded composites confirmed the improved matrix-fiber stress transfer. The 4 Wt.% BN-CEC revealed the highest glass-transition temperature 92°C. The thermogravimetric analysis of the composite exhibited a two-step thermal decomposition: epoxy matrix (nearby 260°C) and carbon fibers (beyond 420°C). The 4 Wt.% MoS2-CEC showed the maximum degree of crosslinking, twice the neat CEC, the MoS2 restrained the mobility of the epoxy chains and decreased the thermal decomposition. Both the filler loaded composites have comparable thermal stability and are significantly improved than the neat CEC. Thus, the composite containing solid lubricant filler up to 6 Wt.% shall be used for high-temperature applications.

In this work Graphene nanoplatelets (GNPs) filled with Linear low-density polyethylene (LLDPE), nanocomposite films designated as LLDPE+1%GNP and LLDPE+5% GNP were manufactured using LLDPE pristine granules, 1 wt. % GNPs-LLDPE, and 5wt. % GNPs-LLDPE masterbatch granules by the extrusion-blow molding process. It was found that the ductile behaviour of neat LLDPE film and nanocomposite films are anisotropic in the machine direction (MD) and transverse direction (TD). The tensile strength of neat LLDPE films in the MD and TD is 25.93 & 20MPa. LLDPE+1GNPs nanocomposite films showed higher tensile strength in the MD and TD 28.38 & 23MPa, and LLDPE+5GNPs nanocomposite films showed 24.36 & 23MPa respectively. The high concentration of GNPs in LLDPE acts as plasticizers increased the elongation, reduced the strength, and increased the rate of thermal degradation. The XRD results reveal additional peeks observed in LLDPE+5GNPs nanocomposite films infer the slight change in crystallinity as compared to neat LLDPE film. This is evident in the change of tensile behaviour of nanocomposite as compared to LLDPE.

In this study, non-hybrid and hybrid (Kevlar, carbon and glass) fabric epoxy composite laminates were fabricated with different stacking sequences by hand lay-up followed by hot-compression molding. Experimental tests were conducted to investigate tensile, flexural, and hardness characteristics. It was found that the stacking sequence did not significantly affect the tensile strength and hardness values of the composites; however, it affected their flexural strength. Damage morphology of the specimens through SEM images showed that the major damage mechanisms in the composites were delamination, fiber breakage, pull-out, and matrix cracking. Based on the static experimental results, the high-velocity impact behavior was investigated through simulation study using LS-DYNA finite element analysis (FEA) software. To study the ballistic impact, a steel projectile with a hemispherical penetrating edge at impact velocities of 100 m.s−1, 250 m.s−1, and 350 m.s−1 was considered. Among non-hybrid fabric epoxy composite specimens, Kevlar/epoxy specimen was found to have the highest impact energy absorption followed by carbon/epoxy and glass/epoxy, respectively. Regarding the hybrid fabric epoxy composite specimens, the ones with Kevlar plies in the rear face exhibited better energy absorption compared to other stacking sequences. The non-hybrid glass/epoxy specimen had the lowest energy absorption and highest post-impact residual velocity of projectile among all specimens. From the FEA results, it was noted that impact resistance of hybrid composites improved when Kevlar fabric was placed in the rear layer. Thus, the stacking sequence was observed to be of substantial importance in the development of fabric-reinforced composite laminates for high-velocity impact applications.

Fiber-reinforced polymer (FRP) composites are widely being used for structural applications due to their attractive properties. Particularly, to fabricate complicated structures by FRP comp...

Green composites, because of its economic advantages and contribution to environmental sustainability, finds its wide range of applications in several industrial sectors. Mechanical characterization of any engineering materials is of utmost importa

Hybrid filler loaded multi-layer polymer composites are becoming one of the suitable alternative material for electromagnetic interference shielding (EMIS) applications. Mainly these composites are manufactured by conductive/magnetic fabrics, foams, foils or films or a combination of all, layered in an orderly architecture to obtain effective EMIS. In this work, dendrite structured copper particulate dispersed in cellulose acetate polymer (CA). We have developed approximately 100-micron thickness of cellulose acetate/copper filler (CA/Cu) films (7–55 wt%) and a neat CA film. The electrical conductivity, tensile strength, percentage of elongation, burst strength and folding endurance of CA/Cu films were measured and compared. The percolation threshold for conductivity was found at 28 wt% and the drastic increase in conductivity at 28–37 wt%. The mechanical strength of CA/Cu composite films was investigated and reported.

Multi-layered carbon fabric-epoxy composites (CFEC) encounter certain challenges in expanding their usage mainly due to their low interlaminar shear strength (ILSS) and sensitivity to delamination damage. The present article focuses on evaluating the effectiveness of the fillers molybdenum disulfide (MoS2) and hexagonal boron nitride (h-BN) (2–8 wt%) on the flexural and the shear properties of the CFEC. The filler dispersion in epoxy resin is achieved by ultrasonication and composite fabrication through vacuum-assisted hand lay-up process. The filler surface area, evaluated as per nitrogen adsorption principles, reveals characteristics of hysteresis isotherm and mesoporous structure in both the fillers. Fourier transform infrared analyses on MoS2 reveal the stretch vibration due to molybdenum-sulfur and disulfide bonds whereas, in the h-BN, the transverse stretching and the out-of-plane bending happen due to boron-nitrogen and the boron-nitrogen-boron molecular group, respectively. Further analysis in the atomic force microscope shows more regular filler distribution at the outer surface for 4 and 6 wt% filler loaded CFEC whereas, 8 wt% filler loading results in an uneven particle distribution and attains the minimum surface roughness. The study exhibits the maximum ILSS (43.46 MPa) which is 43% enhancement compared to the neat CFEC for 6 wt% h-BN loaded CFEC. The maximum flexural strength (532 MPa) was noticed in 4 wt% MoS2 loaded CFEC signifying 62% improvement compared to the neat CFEC. The structural property improvements were witnessed because of the regularly distributed filler that strengthens the fiber-matrix interaction zone and reduces the matrix crack. The findings reveal that the proposed enhanced scheme by solid lubricant fillers proves to be more favorable for improving the matrix-dominated properties and the bending stiffness compared to the other particle-reinforced approaches.

This work aims to evaluate the effect of post-heat treatment and quenching on the hardness, coating thickness, morphology, wear, and microstructure of the coatings made on steel travelers. The test result shows that all the quenched samples have similar hardness. Wear tests of the specimens show that Type-I oil quenched specimens have better wear resistance compared to other specimens. Atomic force microscope results reveal that Type-I oil-quenched travelers have a smoother surface than water and air-cooled travelers. Scanning electron microscope images show that the distribution of plating on the substrate is not uniform. After baking, the coating becomes uniform. However, some small voids are present in the coating due to improper surface activation before the plating process

Epoxy-cashew nut shell liquid (E-CNSL) composites are prepared by open resin moulding method with varying CNSL content (16 to 30 vol. %.). The tensile properties, hardness and impact strength of E-CNSL composites were investigated as per ASTM standards. It is found that the addition of the CNSL in epoxy increases the elongation at break and tensile strength. The 16 vol. % CNSL addition showed maximum tensile strength, and further increased CNSL deteriorates the tensile properties of the resultant composites. Further, hybrid composites are prepared by reinforcing crumb rubber (CR), short banana fibre (BF) and friction dust (FD) in cashew nut shell liquid (CNSL) mixed epoxy. The samples were tested as per ASTM standards to investigate the basic mechanical properties. It is found that the hybrid composite made of 2.5 vol. % CR, 2.5 vol. % FD and 7.5 vol. % BF in epoxy with 16 vol. % of CNSL showed better properties. Further, the specific wear rate, coefficient of friction and rate of water intake is investigated for the hybrid composite and reported

Banana short fiber/Al(OH)3/epoxy composite laminates were prepared by dispersing short banana fiber and Al(OH)3 particulates in an epoxy matrix and investigated for their specific wear rate...

Cryogenic treated multilayered carbon fabric/oxidized multiwall carbon nanotube/epoxy (CCF/O-MWCNT/E) composite and untreated carbon fabric/epoxy (CF/E) composite were prepared by hot compression molding technique. The density and mechanical properties such as tensile properties, flexural properties, interlaminar shear strength, and microhardness of the composites were investigated as per ASTM standards. The wear and coefficient of friction behavior were investigated using computer interfaced pin-on-disc test rig at room temperature for varied load and sliding speed. The morphology of worn surfaces of the wear test composite specimens were studied by scanning electron microscope. It is found that the synergetic effect of addition of O-MWCNT to epoxy matrix and cryogenic treatment of carbon fabric improved the wear resistance and mechanical properties. Also, a thin lubricating film developed by the oxidized multiwall carbon nanotube/epoxy wear debris reduces the coefficient of sliding friction and wear rate.

Waste tyre rubber/epoxy composites were prepared with 15, 30 and 45 Wt.% of recycled waste tyre rubber (WTR) particles (size:100 µm, 200 µm, and 300 µm) as fillers in the epoxy matrix by open moulding method followed by post-curing at elevated temperature. The physical, mechanical and sliding wear behaviour of the composites were investigated. Due to the addition of WRT filler in epoxy enhanced its sliding wear resistance and reduced the modulus of the composites. it is found that both the quantity and particle size of WTR influenced on wear rate. Addition of 15 Wt. % WRT filler enhanced the tensile strength of the epoxy composite, further addition WRT filler deteriorates the tensile strength. Also, investigated the structure-property correlation and observed no correlation between mechanical properties and specific wear rate of WRT/epoxy composites. The morphological study was performed on tensile fractured and on the worn-out surfaces. The investigation revealed that the recycled WTR particles could be used as fillers for epoxy composites and it has potential applications like flooring and anti-corrosion coating, as well as an electrical insulating

Neat glass fabric/epoxy composites (GECs) and multi-wall carbon nanotube/glass fabric/epoxy composites (MWCNTGECs) were prepared by hand-lay-up followed by compression molding technique and investigated the structural properties. It is found that the mechanical properties and wear resistance of the glass fabric reinforced epoxy composite improved upon the addition of MWCNTs. The 0.3 wt%MWCNTs filled glass fabric/epoxy composite (0.3MWCNTGECs) exhibits better properties as compared to 0.075 wt% MWCNT filled glass fabric/epoxy composites (0.075MWCNTCs), 0.15 wt% MWCNT filled glass fabric/epoxy composites (0.15MWCNTCs) and GECs. The mechanism of wear failure of these composites was analyzed from the morphology of worn surfaces. It was observed solid lubricant film established on the wear track at higher normal loads reduces the wear. The correlation of Vickers's hardness and Lancaster factor ( σ e ) − 1 with specific wear rate is investigated and reported.

Cu2SnSe3 has been considered as a potential thermoelectric material owing to its cost-effective and nontoxic constituent elements along with its high electrical conductivity. However, its low Seebeck coefficient has been a concern towards realizing a high figure-of-merit. In the present study, Cu2SnSe3/xSnSe (x = 0, 5, 10, and 20 wt %) composite samples whose thermoelectric performance has been studied in the temperature range 10–375 K, shows that the Seebeck coefficient of sample containing 10% SnSe is ~3.6 times that of the pure. The incorporation of SnSe has resulted in a significant increase in electrical resistivity and Seebeck coefficient which is attributable to the decrease in carrier concentration with increase in SnSe content. Concurrently, a power factor (PF) of 35.60 μW/mK2 has been attained for x = 10% sample at 375 K. However, due to the increase in thermal conductivity with the addition of SnSe, the composites have lower ZT values than that of the pristine Cu2SnSe3 sample. Furthermore, the Vicker's microhardness, which is a key measure for the mechanical strength of a material, has distinctly improved by the addition of SnSe.

Metal-coated synthetic fibe rreinforced polymer composites have been recently used fo rmany electrical and electronic applications. In this direction,due to low weight,non corrosive,and excellent structural properties, the carbon fabric reinforced polymer composites are in high demand.In this work,we have developed Fe2O3 filmonbi-axial oriented plain viewed carbon fabric by spray pyrolysis at various thicknesses using FeCl2. H2O solution.XRD study revealed that the film consisted of α-Fe2O3 and no other crystal line phase was observed.The Fe3+ concentration was varied and the samples were characterized for electrical, magnetic properties and morphology study.The coating on the fabric surface was found to be uniformand covered the entire fiber surface when the spray volume was 40ml.The Fe3+content on the fabric increased with the increase in the solution concentration. It was not icedthatα-Fe2O3 coated on the fabric surface increased the conductivity and magnetic property making this suitable for Electro magnetic interference(EMI)shielding applications

In this paper the ultrasonic test performance of water based Methylcellulose couplant on steel is reported. The couplant used in the ultrasonic testing has an influence on the amplitude of the pulse echo signal. The ultrasonic energy which is transmitted from the transducer to the test material, through the couplant which is present in the interface. The amplitudes of back wall echo increases with increasing acoustic impedance of the couplant. In this research work couplant was prepared by using 0 to 50g of methylcellulose in steps of 10g in 250 ml of water. All five types of water based methylcellulose couplant were used for testing a standard stainless steel calibration U2 block. The effect on the amplitudes of back wall echoes was studied and best possible combination of water and methylcellulose are reported.

The main cause of power loss or dissipation of heat in case of meshed gears is due to friction existing between gear tooth mesh and is a major concern in low rotational speed gears, whereas in case of high operating speed the power loss taking place due to compression of air-lubricant mixture (churning losses) and windage losses due to aerodynamic trial of air lubricant mixture which controls the total efficiency needs to be considered. Therefore, in order to improve mechanical efficiency it is necessary for gear designer during gear tooth optimization to consider these energy losses. In this research paper the power loss analysis for a tooth-sum of 100 altered by ±4% operating between a specified center distance is considered. The results show that negative altered tooth-sum gearing performs better as compared to standard and positive altered tooth-sum gearing.

Jatropha seed cake particulate (JSCP)-reinforced epoxy composites were prepared by open mold resin casting method. The influence of JSCP on mechanical and dry sliding wear properties of epoxy was experimentally investigated as per the ASTM standards. Dry sliding wear test was conducted for these composites at a constant sliding distance of 500 m with different sliding velocities and applied loads by a pin-on-disc wear test machine. The results revealed that incorporation of JSCP decreased the specific wear rate and coefficient of friction while improving the mechanical properties. The composite reinforced with 40 wt% of JSCP exhibited better mechanical properties and wear behavior compared to the neat epoxy and other compositions of JSCP/epoxy composites. The results of this study indicate that jatropha seed cake powder can be used as biosolid lubricant filler for epoxy.

Thispaperpresentsacomprehensiveliteraturesurveyonhybridpolymercompositematerialresearch forelectromagneticshieldingapplications. Itfocusesonelectromagnetic(EM)radiation,mechanism ofelectromagneticinterference(EMI)shieldingandsuitabilityofpolymercompositesfortheEMI shieldingapplications.Basedontherecentliterature,itsummarizesanddiscussesthefabrication, characterization,andresultsofpolymerhybridcomposites.Particulatereinforcedbulkpolymer composites,polymer-basedmicrofilms,multi-layeredpolymer-basedfilmcomposites,hybridfabric reinforcedcomposites,andfoambasedpolymercompositeforEMIshieldingapplicationsare discussed.Inaddition,anattemptismadetosummarizethesalientfeaturesandthechallengesin hybridpolymermaterialdesignanddevelopmentforEMIshieldingapplications

Hybrid composites of bi-directionally woven E-glass cloth/epoxy containing different amounts of silica were fabricated by compression molding. Composites were characterized as per ASTM standards for their tensile and flexural behaviours, inter laminar shear strength (ILSS), impact strength, surface hardness and density. The effect of silica content on wear loss and specific wear rate of the composites was investigated by three body abrasive wear testing under different loads and abrading distances. The lowest wear rate was observed for 3 wt.% silica-filled hybrid composite at an abrading distance of 300 m. 6 and 9 wt.% silica filled composites exhibits lower wear rates at 600 m and 900 m abrading distances compared with 3 wt.% silica filled composite. It is also observed that the specific wear rate strongly depends on the applied load at lower abrading distances in all composites. We have also correlated the mechanical property with specific wear rate and wear loss.

Multi-layered laminates of bi-directionally woven E-glass fabric/epoxy with different loading of graphite particles were made by hand layup followed by compression molding. Tensile and flexural behaviors, impact strength, hardness and density of these laminates were determined. Wear behaviors of these composites were investigated by a pin-on-disc wear test apparatus. Specific wear rates of these composites strongly depend on their filler content and applied normal loads. The hybrid composite containing 3 wt% of graphite exhibits the optimum mechanical and wear performances. A further increase in the graphite content increases the specific wear rate and deteriorates the mechanical behavior. The lowest ( σ e ) −1 factor (the reciprocal of the product of tensile strength and elongation at break) signifies the lowest specific wear rate. The results of the morphology study of the wear test specimens support the results of the wear test.

The estimation of gear tooth stiffness is important for finding the load distribution between the gear teeth when two consecutive sets of teeth are in contact. Based on dynamic model a C-program has been developed to compute mesh stiffness. By using this program position dependent mesh stiffness of spur gear tooth for various profile shifts have been computed for a fixed center distance and altering tooth-sum gearing (100 by ± 4%). It is found that the C-program using dynamic model is one of the rapid soft computing technique which helps in design of gears. The mesh tooth stiffness along the path of contact is studied for both 20° and 25° pressure angle gears at various profile shifts. Better tooth stiffness is noticed in case of negative alteration tooth-sum gears compared to standard and positive alteration tooth-sum gears. Also, in case of negative alteration tooth-sum gearing better mesh stiffness is noticed in 20° pressure angle when compared to 25°., {"references":["Ivana Atanasovska., \"Influence of stiffness and base pitch deviation on load distribution between tooth pairs and involute gear load capacity\", Faculty of technical sciences, Novi Sad, Machine design, 47th Anniversary of the Faculty, pp. 259-264, May 18th 2007.","Wang K. L. and Cheng H. S. \"A numerical solution to the dynamic load, Film thickness and surface temperature of spur gears: part I analysis\", ASME journal of mechanical design, Vol. 103, pp. 177-187, 1981.","Yang D. C. H. and Sun Z. S. \"A rotary model for spur gear dynamics\". ASME journal of mechanisms, transmissions, and automation in design, Vol. 107, pp. 529-535, 1985.","Moore, W. L., \"Low cycle fatigue and ultimate strength related to gear design\". Trans of the ASME, Journal of mechanical design, Vol. 101, pp. 373-379, 1979.","V.Atanasiu, I. Doroftei., \"Dynamic contact loads of spur gear pairs with addendum modifications\", European journal of mechanical and environmental engineering, Vol. 49(2), pp. 21-26, Romania, 2008.","Ali, hammoudi and Amal a. Abdullah. \"Non-linear analysis spur gear mesh by finite element method\", Journal of kerbala university, Vol. 5, No. 4, pp. 260-273, 2007.","C. H. Wink and A. L. Serpa, \"Investigation of tooth contact deviations from the plane of action and their effects on gear transmission error\", Proceedings of the institution of mechanical engineers, Part C: Journal of mechanical engineering sciences, Vol. 219 (5), pp. 501-509, 2005.","Frolov, K.V and Kosarev O.I. \"Control of gear vibrations at their source\", International applied mechanics, 39(1): pp. 49-55, 2003. Doi: 10.1023/A: 1023612015873.","Burgess E.G., Jr. \"Minimization of gear train inertia\". Trans. of the ASME, Vol. 76, pp. 493-496, 1954.\n[10]\tFakhfakh, T, Walha, L, Louati, J, haddar M, \"Effect of manufacturing and assembly defects on two stage gear system vibration\", The international journal of advanced manufacturing technology, Vol. 19(9-10), pp. 1008-1018, 2006.\n[11]\tViktor Skrickij, Marijonas Bogdevicius, \"Vehicle gearbox dynamics: center distance influence on mesh stiffness and spur gear dynamics\", ISSN 1648-4142, Transport, pp. 278-286, 2010. doi: 10.3846/transport.2010.34.\n[12]\tGill- Jeong C. \"Nonlinear behavior analysis of spur gear pairs with a one way clutch\", Journal of sound and vibration, Vol. 301(3-5), pp. 760-776, 2007. Doi:10.1016/j.jsv.2006.10.040.\n[13]\tLitak G, and Friswell M.I., \"Dynamics of a gear system with faults in meshing stiffness\", Nonlinear dynamics, Vol. 41(4), pp. 415-421, 2005, Doi: 10.1007/s11071-005-1398-y.\n[14]\tA. Palerno, D. Mundo, A.S. Lentini, R. Hadjit, P. Mas and W. Desmet., \"Gear noise evaluation through multibody TE-based simulations\", Proceedings of ISMA leuven, belgio, pp. 3033-3046, 2010.\n[15]\tLin T. and Seireg A., \"An optimum design algorithm for gear systems incorporating surface temperature\", Vol. 41(4), pp. 415-421, 2005, Doi: 10.1007/s11071-005-1398-y.\n[16]\tSachidananda, H, K. Joseph, G. and Prakash, H. R. \"Analysis of contact stresses in altered tooth-sum spur gearing,\" Journal of applied mechanical engineering, Vol. 1(1), pp. 1-5, 2012.\n[17]\tSachidananda, H. K., K. Raghunandana. and J. Gonsalvis \"Design of spur gears using profile modifications,\" Tribology Transactions, Vol. 58(4), pp. 736-744, 2015.\n[18]\tA. D. Lin and J H. Kuang. On the bending and surface fatigues of an engaging, spur gear pair, 12th IFTMM world congress, Besancon (France), June 18-21, 2007.\n[19]\tYang Y. T. and Kuang J. H., \"An estimate of mesh stiffness and load sharing ratio of a spur gear pair\". Proceedings of ASME 12th International power transmission and gearing conference, Scottsdale, Arizona, De-vol. 43-1, pp. 1-10, 1992."]}

Nanocomposites were prepared with Al/Al-Si alloys (LM 6 and LM 25) as matrix and multi wall carbon nanotube (MWNT) of 0.25, 0.5, 0.75, 1.0 and 1.5 wt. % as reinforcement through powder metallurgy (PM) followed by sintering and hot extrusion techniques. Fabricated nanocomposites were machined on a Panther 1530/1650 lathe by using tungsten carbide tool. Recurrence quantification analysis (RQA) was used to study the machining characteristics by using cutting force signal stability. Highest value of determinism (DET-one of the RQA parameter) was observed for 0.5 wt.% MWNT reinforced Al and Al-Si nanocomposites. This attributes better machining characteristic due uniformity of the signals. Also it is observed better mechanical properties at 0.5 wt.% reinforced nanocomposite and further reinforcement deteriorate the machinability and mechanical properties. Copyright © 2011 VBRI press.

The design, fabrication, and testing of an epoxy-glass reinforced polymer composite pressure vessel suitable for high-pressure gas storage have been reported. In this study composite pressure vessels are made up of aluminum alloy 6063 seamless liner and glass/epoxy composite reinforcement. The aluminum liner, which is developed by extruded aluminum tube of internal diameter 141 mm and wall thickness 4 mm, is subjected to super plastic deformation. Continuous glass fibers impregnated in epoxy resin are wound on the seamless liner by filament winding process. In this work, 10 pressure vessels were manufactured for 3.5 MPa service pressure with marginal safety of 3. Four pressure vessels were subjected to cyclic and burst test; the burst pressures were 10.9, 11.0, 11.0, and 13.0 MPa.

Aim: To compare the incidence of apical root crack formation after root canal preparation at different instrumentation lengths using ProTaper Universal (PTU), ProTaper Next (PTN) and ProTaper Gold (PTG) file systems. Subjects and Methods: Eighty-four mandibular first premolars with single and straight root canal were mounted in resin block after simulating periodontal ligaments. 1–2 mm of root apex was exposed followed by sectioning of 1 mm of root tip for better stereomicroscopic visualization. While the Control group was left unprepared, experimental groups were instrumented up to root canal length (RCL) and (RCL-1 mm) respectively using PTU, PTN and PTG. After staining the root apex with 1% methylene blue dye, stereomicroscopic images were obtained for evaluating apical root cracks. The data were analyzed using Chi-square, phi and Cramer test. The significance level was set at P < 0.05. Results: Significantly less dentinal defects were seen between PTG and PTU while there was no significant difference between PTU-PTN and PTN-PTG. Furthermore, samples instrumented up to RCL-1 mm showed lesser cracks as compared with samples instrumented up to RCL. Conclusion: PTG produced least number of cracks followed by PTN and PTU. Furthermore, instrumenting short of RCL reduced the crack formation risk.

Nano particulate composites with Al-Si alloys (LM6 and LM25) as matrix and Multiwall Carbon Nanotube (MWNT) as reinforcement (0.25, 0.5, 0.75, 1.0 and 1.5 weight percentage) have been fabricated by powder metallurgy process. Damping specimens were prepared according to ASTM E 756-05 standard and the specimens were subjected to free vibration test to investigate the damping ratio and natural frequency. It is observed from the free vibration test data; both alloys (LM6 and LM25) have shown significant improvement in damping ratio, natural frequency and modulus when reinforced with 0.5 weight percentage of MWNT. Increase in weight percentage of MWNT beyond 0.5 leads to deterioration in damping ratio, natural frequency and modulus. This is due to agglomeration of reinforcement phase. The same has been observed in the morphological study using transmission electron microscopy (TEM). In this work an attempt has been made to also investigate the mechanical properties of the fabricated composites.