Applied Mechanics and Materials Vols. 592-594

Abstract: The usage of a conventional cutting fluid in the metal cutting operations gives harmful effect for environment and to the operator’s health. In this study, experimental investigations were carried out in a drilling operation on aluminium alloy material using a liquid nitrogen (LN₂) coolant. The variables in the experiment were, cutting speed and feed, the drilling depth was maintained constant. For each feed rate (0.02, 0.05 & 0.08 mm/rev) three holes were drilled for cutting speeds 110, 130 & 150 m/min. The cutting temperature and thrust force were recorded. The cutting temperature and thrust force were reduced, when cutting speed was increased. The hole quality parameters like cylindricity, circularity and perpendicularity were analyzed using CMM.

Abstract: This paper focuses on optimization of process parameters for wire electric discharge machining (WEDM) of In-situ Al7075-TiB₂ metal matrix composites processed by stir casting technique using Taguchi method of experimental design. The effect of pulse-on, pulse-off, current, and bed speed on dimensional accuracy, surface roughness and volumetric material removal rate (VMRR) have been investigated keeping voltage and flush rate constant. L₂₇ orthogonal array of Taguchi technique was used for experimental trials. The optimum process parameters have been identified. Significant process parameters were identified from the analysis of variance (ANOVA). Further, verification experiment has been carried out to confirm the performance of optimum process parameters.

Abstract: This research work mainly deals with the mechanical and microstructure properties of various thermal barrier coating (TBC) materials for an internal combustion engine piston using plasma spraying technique. Three thermal barrier coating Materials namely the combination of Aluminium Oxide with Titanium oxide (87%Al₂O₃ + 13%Tio₂), Aluminium Oxide with Titanium oxide (97% Al₂O₃ +3%Tio₂) and Yttria Stabilized Zirconia (YSZ) (100%) were selected and coated on Aluminium Alloy(Al Ai) with the thickness of 150 Microns (µm) for this investigation. Among three Thermal barrier coating materials, Yttria Stabilized Zirconia showed better mechanical properties such as elongation (EL) of 6.25%, tensile strength TS of 106.06MPa and yield strength (YS) of 90.34MPa when compared with that of the base piston metal Aluminium Alloy (Al Ai). Further, better microstructure properties were also observed for YSZ (100%) in comparison with other thermal barrier coated materials.

Abstract: Carbon fiber reinforced plastics (CFRP) are used as structural materials in automotive and aerospace industries because of its superior properties like high strength to weight ratio and high stiffness to weight ratio. Though most CFRP products are produced to near net shape by different composite manufacturing methods, some post machining processes such as drilling, edge trimming are required. In order to shape and smooth the edges of the composite components the edge trimming plays a major role. This research gave the approach of studying the effect of temperature and tool wear on surface roughness obtained during edge trimming of uni directional CFRP with different fiber orientations and quasi isotropic CFRP with the sequence of [90/-45/0/45/90/-45/0/45]_S. The effect of coating of tool on tool wear and surface roughness were also studied.

Abstract: In recent trend, the most used fiber reinforced composite is the glass fiber composite. The glass-fiber composites have high strength and mechanical properties but it is costlier than sisal and jute fiber. Though the availability of the sisal and jute fiber is more, it cannot be used for high strength applications. A high strength-low cost fiber may serve the purpose. This project focuses on the experimental testing of hybrid composite materials. The hybrid composite materials are manufactured using three different fibers - sisal, glass and jute with epoxy resin with weight ratio of fiber to resin as 30:70. Four combinations of composite materials viz., sisal-epoxy, jute-epoxy, sisal-glass-epoxy and sisal-jute-epoxy are manufactured to the ASTM (American Society for Testing and Materials) standards. The specimens are tested for their mechanical properties such as tensile and impact strength in Universal Testing machine. The results are compared with that of the individual properties of the glass fiber, sisal fiber, jute fiber composite and improvements in the strength-weight ratio and mechanical properties are studied.

Abstract: The properties of fiber reinforced composites (FRP) like high strength to weight ratio, high stiffness to weight ratio, flexibility in design, ease of fabrication with economical savings as compared to metal alloys, make it an excellent choice for various range of products from building materials, sporting equipment, appliances, automotive parts, boats, canoe hulls to bodies for recreational vehicles. In this study the properties of natural fibre composite are compared with composite made of artificial fibres. The natural fibre chosen is jute fibre and the artificial fibre chosen is glass fiber. Polyester resin was the matrix used because of compatibility, cost effectiveness and easy availability. The composites were fabricated by Hand Layup technique and the number of layers of composite laminate was varied as three, four and five. The specimens were subjected to mechanical tests and Young’s Modulus, Ultimate Strength were evaluated. Modal analysis was carried out to determine the damping characteristics through damping ratio. A comparison of the two composites in terms of mechanical properties is made and the results are tabulated.

Abstract: Aluminium alloy (AA7075) is largely used in various fields of transport applications, including marine, automotive and aviation and aerospace due to their high strength-to-density ratio. The present work deals with the influence of TiC on the mechanical behavior of AA 7075 composites. TiC is particularly attractive as it offers high hardness and elastic modulus, low density, good wettability yet low chemical reactivity with aluminium melts. The aluminium metal matrix composites (AMMCs) are produced as AA 7075 matrix metal and TiC particulates of an average size of 2µm as reinforced particles through stir casting, Magnesium added to the melt to overcome the wetting problem between TiC and liquid AA7075 metal. AMMCs are produced in different %weight of TiC ranging between 2 to 10%.These composites are characterized with optical, SEM and EDS analysis in as-cast condition and T₆condition and hardness are predicted using macro vickers hardness tester. The test results showed increasing hardness of composites compared with matrix (AA7075) because of the presence of the increased reinforced material (TiC)

Abstract: Surface finish and Manufacturing process has a prominent role in the fatigue life of a machine component. Fatigue strength of a material generally increases with the surface finish. But the super finishing process like electro polishing reduces the fatigue strength of the material. In Abrasive flow machining it is found that surface finish and fatigue strength always increasing. In Abrasive flow machining the fatigue strength is mainly governed by the process variables extrusion pressure, abrasive concentration and mesh size. This research studies the influence of the process variables on the fatigue strength of the material. In this study an approximate surface finish of 4μm is obtained after AFM. The effect of three process variables on the response function selected, fatigue strength, were studied. A statistical 2³ full factorial experimental technique is used to find out the main effect, interaction effect and contribution of each variable on fatigue strength. The instron machine is used to find out the number of cycles to failure of the material. The fatigue strength is obtained with S-N curve analysis.

Abstract: During last few years, the interest in using natural fibers as reinforcement in polymers has increased significantly. Natural fibers are not only strong and lightweight but also relatively very cheap and bio-degradable. In this work, an investigation is carried out on jute fiber, a natural fiber. Jute fiber has gained interest in the composite field due to its superior specific properties compared to manmade synthetic fibers like glass, Kevlar, asbestos, etc. The present work describes the development and characterization of natural fiber based composites consisting of jute fiber as reinforcement and hybrid resin consisting of general purpose resin and cashew nut shell resin as matrix material. The composites are fabricated using hand lay-up technique. The tensile strength is studied using experimental and numerical analysis. The nature of hybrid matrix at different composition is also studied. The commercial Finite Element Analysis software ANSYS is used for numerical study.

Abstract: In this research work, thermo-elasto-plastic analysis using finite element modeling (FEM) was carried out to study the thermo mechanical behavior of AISI 304L stainless steel plate of 3 mm thick during the autogenous tungsten inert gas welding. Sysweld software has been employed for simulating the temperature distribution, residual stresses and distortion. Physical and mechanical properties of 304 L stainless steel required for simulation were obtained from the literature. Bead-on-plate experiment was carried out at 140 A and 120 mm/min for obtaining weld bead dimensions which are required for heat source fitting in the simulation. Heat source parameters in the simulation were frozen when the bead profile obtained in the simulation matched with the actual bead profile. Then thermal cycles were simulated with the frozen heat source parameters. The thermal cycles and the peak temperatures predicted by the model were compared with that of the experimentally measured values. There was good agreement between the predicted and measured values. The experimentally validated thermal model was further used for simulating residual stresses and distortion. The calculated residual stress profile was validated using experimentally measured residual stress profiles using an Ultrasonic technique. There was good agreement between the predicted and measured residual stress profiles. The simulated distortion values were compared with measured distortion values using height gauge. There was good agreement between the simulated and measured distortion values. The Finite Element model developed for simulating the TIG welding of 304 L stainless steel predicted the thermal cycles, residual stresses and distortion with minimum error.