Applied Mechanics and Materials Vols. 592-594

Abstract: Composite materials are widely used for their superior properties such as high strength to weight ratio, high tensile strength, low thermal expansion, low density etc. Due to environmental issues the eco-friendly composites are being explored. Natural fibers as reinforcement for polymer composites are widely studied. But natural fibers lack better mechanical properties when compared with synthetic fibers. Hence mixing the natural fiber with a synthetic fiber such as glass fiber will improve mechanical properties of the composites. In this study banana fiber is mixed with glass fiber, and the mixture is used as reinforcement in epoxy matrix. The composite specimens were prepared using hand layup technique, the fibers were randomly oriented. Further the fiber length was varied as 10, 15, 20 and 25mm and volume fraction as 10%, 15%, 20% and 25%. Experiments were conducted to find the effect of fiber length and volume fraction on tensile strength, flexural strength, water absorption properties of the composites. It is observed that a fiber length of 20mm and 20% fiber volume fraction gave better mechanical properties.

Abstract: In this present work the influence of Cenosphere filler material in thermal and mechanical properties of Epoxy resin is discussed. For comparative study, pure resin and composites made with different compositions (1, 3 and 5 wt% of Cenosphere) were prepared. The specimens were submitted to thermal analysis (DMA) and mechanical test (Tensile and Flexural) as well. Dynamic mechanical analysis (DMA) revealed an enhancement in the energy dissipation ability of the composite with 1wt%, wt3%, wt5% of Cenosphere and an increase in stiffness relative to the pure matrix phase. It was generally observed that the tensile strength found to increase with the inclusion of Cenosphere as filler material. Maximum value of tensile stress and strain of resin is not sensitively increased by filler material.

Abstract: Productivity enhancement assumes a paramount importance in today’s competitive industrial world. The aim of this work is to improve productivity in a conventional lathe with two single point cutting tools machining a workpiece simultaneously. An additional tool holding fixture is fabricated and integrated so that distance between the two cutting tools can be varied and has a provision to provide individual depth of cut. Experiments were performed on gray cast iron workpiece at different offset distances between the cutting tools, at a particular cutting speed, feed rate and depth of cut. In the multi-tool turning process, lagging rear cutting tool experiences lesser cutting force than leading front cutting tool. This behaviour is due to the machining of front cutting tool preheat as well as reduction of effective cutting speed while machining with rear cutting tool. With increase in offset distance, moment acting on the work piece contributes to increase in resistance against machining and hence front tool experiences higher force than rear cutting tool.

Abstract: Aluminum alloys are mostly used for high strength structural applications utilized in aircraft structure, trucks body, military vehicles, bridges and weapons manufacture. Conventional fusion welding of aluminum alloy produces porosity and hot cracks in the welded joint due to incorrect selection of consumables and parameters, which may lead to lower weld toughness and defects in the mechanical properties. The mostly adopted method for welding AA 2014-T6 is solid state joining process. Friction stir welding (FSW) is an emerging solid state of joining process which avoids bulk melting of the basic material, hot cracking and porosity. The welding parameters and tool pin profile play a major role in deciding weld quality. In this investigation, an attempt has been made to understand the various influences of tool rotational speed, welding speed and pin profile of the tool on friction stir processed (FSP) zone formation in joining of AA2014 aluminum alloy. High Carbon High Chromium steel tool of plain cylindrical pin profile is used to fabricate the joints. The average grey relation grade for each level of each factor are calculated and it was found that the optimal settings of the levels of factors Tool rotation speed (A), Weld speed (B) and Tilt angle (C) are A1-B3-C3. The findings from these investigations will be presented and discussed.

Abstract: Application of borosilicate glass in Micro Electro Mechanical Systems (MEMS) devices are increasing due to many of its intrigue properties. Micro machining of glass for such applications needs hybrid technology so as to produce precise products. Electro Chemical Discharge Machining (ECDM) has proved immense potential in micro machining of glass. Present paper focuses on the effect of various process parameters of μ-ECDM on Heat Affected Zone (HAZ) while machining borosilicate glass. Grey Relation Analysis (GRA) is used to optimize the process variables. The optimized process variables are confirmed with experimental results.

Abstract: Micro EDM is a nonconventional machining method which has gained researcher’s attention during the past decade. After the success in industrial applications of EDM, focus has been to scale down the entire system to a smaller size. The capability of the process to machine extremely hard and difficult to machine materials has made it a suitable candidate for machining the next generation engineering materials. In this paper, an attempt has been made to develop μEDM setup with piezo actuated tool feed mechanism. The holes are machined on copper plates of thickness 300μm with varying process parameters like voltage, frequency and duty cycle. The design of experiment method has been used to carry out the experiments in a systematic manner. The quality of holes produced is studied using optical microscope and SEM images. The results obtained are presented in this paper.

Abstract: Friction stir processing (FSP) is as a novel modifying technique to synthesize surface composites. An attempt has been made to synthesis AA6082/TiC surface composite using FSP and to analyze the effect of tool rotational speed on microstructure and microhardness of the same. The tool rotational speed was varied from 800 rpm to 1600 rpm in steps of 400 rpm. The traverse speed, axial force, groove width and tool pin profile were kept constant. Scanning electron microscopy was employed to study the microstructure of the fabricated surface composites. The results indicated that the tool rotational speed significantly influenced the area of the surface composite and distribution of TiC particles. Higher rotational speed provided homogenous distribution of TiC particles while lower rotational speed caused poor distribution of TiC particles in the surface composite. The effect of the tool rotational speed on microhardness is also reported in this paper.

Abstract: Magnetically Impelled Arc Butt (MIAB) welding is an unique forge welding process in which an arc is drawn in the gap between the two tubes to be welded in order to raise them to a high temperature to allow forging to form a solid state weld. This paper presents the investigations carried out on MIAB welding trials of carbon steel tubes with varying upset current. Upset current is the short pulse of high current applied prior to upset. It plays a significant role in expulsion of molten metal and impurity from weld interface. This study aims at studying the effect of upset current on weld properties. Carbon steel tubes of SA-210 Grade A have been chosen with outside diameter of 44 mm and thickness of 4.5 mm. Mechanical and microstructural characterization of MIAB weldments was carried out. Good correlation exists between the mechanical properties/microstructure and upset current. Lower upset current has detrimental effect on weld tensile strength due to incomplete expulsion of decarburized zone.

Abstract: History is often marked by the materials and technology that reflect human capability and understanding. Many a times scales begins with the stone age, which led to the bronze, iron, steel, aluminium and alloy ages as improvements in refining, smelting took place. Science made all these possible to move towards finding more advanced materials.Therefore in the present research work, an investigation has been carried out to fabricate and evaluate the microstructure, strength, micro hardness of chilled composites consisting of nickel matrix and fused SiO₂ particles as the reinforcement (size 40-150 μm) in the matrix. The reinforcement being added ranges from 3 to 9 wt. % in steps of 3%. The resulting composites cast in moulds containing metallic chill blocks (MS, SiC & Cu) were tested for their microstructure and mechanical properties. The main objective of the present research is to obtain fine grain Ni/SiO₂ chilled sound composite having very good mechanical properties. A detail of melting and composite preparation is described elsewhere by number of researchers. After melting the matrix material in an induction furnace at around 1600 °C in an inert atmosphere, coated fused SiO₂ particles preheated to 500 °C were introduced evenly into the molten metal alloy by means of special feeding attachments. The moulds for the plate type of castings 150*20*20 mm (American Foundrymen Society standard) were prepared using silica sand with 5% bentonite as binder and 5% moisture and finally they were dried in an air furnace at a temperature of 1580 °C, which was cooled from one end by a chill block set in the mould. After solidification the specimens of chill end were tested for various mechanical and microstructural studies. Keywords: Metal matrix composite, Mechanical properties, Nickel alloy, Fused silica, Chills.

Abstract: The effect of processing parameters on the mechanical and microstructural properties of dissimilar AA6061 t6–AA5083 0 joints produced by friction stir welding was studied. Different samples were produced by varying the advancing speeds of the tool as 20 and 40 mm/min and by varying the alloy positioned on the advancing side of the tool. In the various trials the rotating speed is varied from 600 to 900 RPM. All the welds were produced perpendicular to the rolling direction for both the alloys. Micro hardness (HV) and tensile tests performed at room temperature were used to evaluate the mechanical properties of the joints. Various tests were performed on the joints previously subjected to ageing. In order to analyze the micro structural evolution of the material, the welds’ zones were observed optically.