Mechanical Engineering

This paper describes the study of coefficient of thermal expansion (CTE) of as-cast and heat treated aluminium 7075/ SiC composites. These composites were subjected to different aging durations. The stir casting technique is used to prepare the castings. Castings were machined in accordance with ASTM standards followed by heat treatment process. All the castings were aged to different periods of 1hr, 3hr, 5hr at an aging temperature of 175 oC. Coefficient of thermal expansion tests were performed in both as-cast and heat treated conditions. In each case the coefficient of thermal expansion values were found to increase with increase in aging durations. Solution heat treatment at 530 oC followed by artificial aging at 175 oC found to increase in dimension change of every specimen tested. The coefficient of thermal expansion curves exhibited some residual strains, which were decreased with the increase in aging durations.

Nowadays, biodiesel is considered the most promising alternative fuel by the researchers due to its comparable properties with diesel fuel and also other socio-economic and environmental benefits .The investigation was conducted on a single cylinder four stroke variable compression ratio diesel engine fuelled with pure diesel, B10% (5% Methanol+ 5% Rice bran oil + 90% Diesel), 20% (5% Methanol+15% Rice bran oil +80% Diesel) and 30% (5% Methanol+25% Rice bran oil+ 70% Diesel) at different loads, at different compression ratios and at different injection pressures. The water heat loss, exhaust heat loss and unaccounted heat loss decreased with the increase of biodiesel percentage in the blends. The heat balance was in respect of useful work (HBP), heat lost through cylinder jacket water (HJW), heat lost through exhaust gasses (HGas), heat carried away by the lubricating oil and other losses (Hrad). This research work provides an in-depth analysis of the engine heat losses in different subsystems of the engine. Finally, heat energy balancing of the engine has been done by showing all energy flows in and out of the engine.

The purpose of this review paper is to discuss the lean implementation and its quantified benefits for the textile industry. Both current and future state maps of the organization’s shop floor scenarios are discussed using lean techniques in order to highlight improvement areas and to bridge the gap between the existing state and the future state of shop floor of the textile industry. After an exhaustive review it is being found that lean implementation has many benefits at organizational and operational level. It has been concluded that, still many of the Indian textile industry have not adopted lean and it may be beneficial for them.

Wind energy as a power source is attractive as an alternative to fossil fuels, because it is plentiful, renewable, widely distributed, green, and produces no greenhouse-gas emissions. A performance improvement of the scoop-vane vertical axis wind turbine is described. To improve the performance of the power generation system design of special frame of vertical axis wind turbine which consists of three movable vanes, this uses more effectively the wind energy and depends only on the acting area of the movable vanes. The frame of the wind turbine is designed to increase the drag coefficient. The new frame design makes using the kinetic energy of the wind to increase the positive torque of our model and tested it practically in wind tunnel as well as tested by solid works software. This model shows batter performance in terms of high drag coefficient and increase torque per frame in the direction of wind.

In this study, the effects of Lpg–gasoline (10%, 20%, 30% LPG and 100% Gasoline) dual fuels on the performance of a single cylinder 4 stroke spark ignition (SI) engine were investigated. In the theoretical study, the Single-cylinder, four-stroke, Single-point injection system SI engine fitted to a Generator was used. For this purpose, simulations were carried out using AVL Boost Software, without catalytic convertor under constant engine speed (3600 rpm) and varying load conditions. The variations in Performance brake power, Torque, brake specific fuel consumption, and exhaust gasses were examined at varying compression ratios for dual fuel single cylinder SI engine. Variable compression ratio (VCR) technology has long been recognized as a method for improving the fuel economy of SI engines. The results obtained from the use of Lpg–gasoline dual fuel were compared to those of gasoline fuel. The results indicated that when Lpg–gasoline dual fuel were used, the brake specific fuel consumption increased and engine performance parameters such as torque and power increases with increasing Lpg amount in the blended dual fuel. Positive results were obtained at all LPG usage levels in terms of exhaust emissions. Best results were achieved at using 100% Gasoline for exhaust emissions.

This paper utilized Taguchi robust design of experiment to obtain the optimum response and optimum setting of control factors affecting the impact strength response of ukam plant fiber reinforced CNSL biocomposite. Fiber Orientation (A), Fiber volume fraction (B) and Aspect ratio(C) are the considered process parameters used in the study. Charpy Impact test was carried out considering Standard L9 orthogonal array for the nine experimental runs and the optimization was done based on a larger is better Signal Noise ratio. Fiber volume fraction had the most significant effect on impact strength response evaluated. The optimum impact strength was captured as 11.12963KJ/m2.

The second order slip boundary condition influence on diffusion of chemically reactive species of non-Newtonian fluid over a vertical permeable linearly stretching or shrinking sheet with surface mass transfer is considered using a second order slip flow model. Casson fluid model is used to characterize the non-Newtonian fluid behavior. The first order chemical reaction is considered. Choosing appropriate similarity variables, the partial differential equations are transformed into a set of non-linear self-similar ordinary differential equations, which are then solved numerically using the function bvp4c from Matlab for different values of the governing parameters. The results clearly show that the second order slip flow model is necessary to predict the flow characteristics accurately. A comprehensive numerical computation is carried out for various values of the parameters that describe the flow characteristics.

Ferrous, non-ferrous metals and alloys are melts and reshape them into finished shape through pouring molten metal into a mold cavity through solidification. The present review confines itself to the literature on the understanding of necessary conditions that are affect the casting properties i.e.grain nucleation, grain growth and other properties of solidified finished shape. After completion of nucleation, solidification process will continue with the growth of nuclei. The number of nucleation sites in casting nucleation and growth of grain refinement can be achieved by increasing the grain refinement is important. In general, finer grain size leads to high mechanical properties such as tensile strength, hardness, toughness, fatigue strength and yield. Mechanical properties and grain refinement can be achieved by the mold rotation, mechanical vibration and electromagnetic stirring. In this paper also review the cooling rate, nucleation presents, grain size, grain growth and solidification behavior change under static and oscillatory casting conditions.

Carbon fibers have been considered as so important reinforcements for aluminum alloys in manufacturing advanced composite materials. Composite materials have been used in automobile, ships aircraft, sports goods and so on. This study discussed the experimental results on tensile strength and modulus of three samples, at different orientations and constant volume fraction of 60% of carbon fibers reinforced aluminum matrix composites at low temperatures. Several experimental tests have been carried out at longitudinal (0°) and transverse (90°) directions of composite specimens using an environmental test chamber with a universal testing machine. Thermo-mechanical tensile loads at strain rate of (0.0015 s-1) were applied to carbon fiber/Aluminum laminates at room temperature (RT=23 0C, zero 0C, -15 0C and -30 0C). The results indicated that low temperatures have a significant effect on mechanical properties i-e tensile and modulus. It was found that the tensile strength for sample S1 reduced as the temperature decrease for both directions while S2 didn’t effect by low temperatures in transverse direction but the strength was reduced at -30 0C by 10% compared to RT in longitudinal direction. It was also observed that for S3, the tensile strength was reduced at -30 0C for both directions. The modulus of the three samples was increased as the temperature reduced. The experimental results also indicated that the strength and modulus for the three samples are higher in longitudinal laminates compared to transverse laminates at low temperatures.

In the work present, describes an attempt has been made to study the effect of temperature on plain fatigue behavior of polyester reinforced with woven of fiber glass manufactured as a laminate [0/90]3.Fatigue tests were carried out at constant and variable temperature environment. All fatigue tests were employed at stress ratio R=-1 and under constant fiber volume fraction (VF) of 33%. The results indicated that the tensile and the fatigue strength decreased with increasing temperature up to at 60 ⁰C. The fatigue strength reduction factor (FLRF) at 60 ^oC was (46%) compared to (RT) environment. A nonlinear fatigue damage model was proposed taking into account the effect of temperature sequence and fatigue loading. This model was calibrated against experimental data under different thermal conditions. The final conclusion which derived from this work was the verification of the model results with the experimental ones.