Mechanical Engineering

Friction Stir Welding, a relatively new welding process, was developed in 1991 at The Welding Institute near Cambridge, England. In this process parts are mated together, rigidly fixtured, and joined in solid-state by forcing a rotating tool into the joint, and traversing that tool along the joint. This process creates weldments with properties comparable to the base metal and in most cases superior to traditional fusion welding techniques. During the Friction Stir Welding (FSW) process, the forging forces under the tool plastically deform the material, “stirring” the material around the tool pin and against the tool shoulder, thus joining the mated parts together. This process induces large shear forces in the plastically deforming material, raising the temperature of the material to approximately 80% of the melting temperature. The FSW process parameters such as tool rotational speed, welding speed, axial force, etc. play a major role in deciding the weld quality. In present investigation, the effect of processing parameters on mechanical properties of AA6082-O joints produced by friction stir welding was analyzed. Different welded specimens were produced by varying rotating speeds of the tool as 900 & 1200 rpm and by varying welding speeds as 50 & 63 mm/min. The FSW joints mechanical properties of the material such as yield strength, tensile strength and percentage of elongation were evaluated by means of tensile tests.

Investigation of the sandwich structures under bending has an important role to understanding the composite structures stability. Bending behavior of sandwich structures has a wide range of applications in science, engineering and technology. In this study the effects of core shape, cell wall height, wall thickness and skin thickness on critical bending load of honeycomb sandwich panels have been investigated. The other parameters of sandwich panel supposed constant during all analyses. The finite element simulation has been carried out with using of ABAQUS software and results were compared with experimental results. After that design of experiment based on Taguchi method has been carried out for understanding the effect of investigated parameters on maximizing the critical bending load. Eventually, the effect of parameters has been investigated with using of ANOVA.

This study is to find out the best optimum ratio of the mixed waste materials of high-density polyethylene and wood’s flour by comparing the mechanical properties of recycled product (WPC). In this study, the fabrication process of wood plastic composite (WPC) contained of virgin material, post-consumer high-density polyethylene, and wood’s flour is through a twin-screw extruder and hot compression machine. The WPC product with four different ratio filler content based on weight percentage, i.e. 0 wt %, 20 wt %, 30 wt % and 40 wt % , were tested using universal tensile machine and impact tester according to ASTM D 3039, ASTM D 790, and ASTM D 6110 . The results of experiment showed that tensile and flexural properties of the composite increased with the adding of the wood’s flour material. The testing showed, however, totally opposite to the result of the impact test. In overall, the results of observations showed that recycled WPC have better mechanical properties compared to non-recycled WPC.

Gender differences played an important role in theoretical mechanics to influence students’ learning interests, academic interests and achievements. In order to improve teaching quality and assist students’ learning, we used SPSS to analyze the data of theoretical mechanics test, gained a comprehensive understanding of gender differences on the theoretical mechanics teaching. The findings of the study indicated that the gap of gender difference exists in theoretical mechanics learning. The test showed female students get higher points in theoretical mechanics test. The result of t-test for two groups of male and female students showed that they had significant difference in terms of mean scores obtained in choice questions, calculating questions, particle mechanics and rotating reference frame tests.

In this paper, some engineering properties of sugar cane stalk are determined. For this purpose, two varieties of sugar cane including L310 and L820 varieties with average moisture contents of 76.4 and 73.8% wet basis, respectively, were used. The experiments were conducted at ten internode positions down from the flower for both varieties. Based on the results obtained, the averages of stalk’s diameter, cross-section area and second moment of area of L310 variety were higher than those of L820 variety, while the average of stalk’s length of L820 variety was higher than that of L310 variety. The internode position had no significant effect on the shearing and bending properties of both varieties. Furthermore, there was significant difference between the two varieties in the case of Young’s modulus, while there was not any difference in the case of shear strength, specific shearing energy and bending strength. The average of Young’s modulus of L820 variety was significantly higher than that of L310 variety. The mean values of shear strength, specific shearing energy, bending strength, and Young’s modulus of L310 and L820 varieties were obtained as 4.92 and 5.25 MPa, 53.36 and 57.35 mJ mm^-2,  9.58 and 9.20 MPa, and 18.81 and 24.50 MPa, respectively.

A thick-walled 90° elbow pipe is of particular interest due to its frequent usage in industrial systems such as chemical processing plants and petroleum refineries. Elastic stress analysis of thick walled pipe elbows using finite element computer software, such as ABAQUS was investigated. The current study shows that the stress level is influenced by the effects of the ratios of bend radius to pipe mean radius (R/ ) and mean radius to wall thickness ( /t) and value of internal pressure. The investigation is limited to include the elastic stresses due to internal pressure and stress variation which was found to be similar to that of a theoretical study reported in the literature. The stress along a thick-walled 90° elbow pipe with the increase in the inner radius, thickness and pressure increases the stress. Based on the variance analysis, the predictive models in this study are believed to produce values of the elastic stress of a thick-walled 90° elbow pipes close to those readings recorded numerically with a 96.5% confident interval.

The objective of this study was to design a singulation system for proper presentation of rice kernels to be analyzed by vision-based rice inspection systems. In order to achieve this goal, several ideas were examined and the preference of each design over the others was evaluated using the Multi-Criteria-Analysis (MCA) method. The proposed designs included a grooved conveyor belt, dual conveyor singulation device, vibrating tray, circular positioning device, and ejection nozzles. The assessment criteria considered in this research included complexity, fabrication cost, feasibility of implementation, singulation speed, and singulation accuracy. After executing the MCA method, the dual conveyor singulation design was selected as the best design for implementation. A prototype of the selected idea was then constructed and its performance was evaluated practically at different transmission frequencies (TFs) of the conveyor’s variable speed drive and discharge rate (DR) of kernels on the conveyor surface. Results of evaluation showed that in all of the DRs the singulation efficiency increased with transmission frequency. The results also revealed that for all of the evaluated TFs, increasing the discharge rate decreased the singulation efficiency. For all of the evaluated DRs, a somewhat irregular increase was observed in the number of singulated kernels with increasing TF. The highest singulation efficiency was equal to 93.09 % which was obtained at DR of 60 g/min and TF of 60 Hz. The highest number of singulated kernels was equal to 94.75, on the average, which was achieved at DR of 60 g/min and TF of 50 Hz

This is the study to evaluate the performance of new design of biogas unit and to enhance the biogas production by using different parameters. The raw material to be fed in digester will be the food waste which gets generated everyday from restaurant full of crowd in the locality. With this unit, biogas equivalent to two kg of LPG can be generated from the feeding of approximately 15 kg of food waste every day. This is the only design available which allows the user to choose how much biogas pressure he wants. Biogas thus produced can be checked for quality by different inoculums and additives. Thus the cost of disposing the food waste can be saved and the energy can also be recreated and reutilized for restaurant benefits. Hence the atmospheric contamination automatically gets prevented.

Harvesting solar energy has been the keen focus of study among researchers all over the globe. In the current scenario of fast depleting non-renewable resources, efforts have to be made for maximum utilization of available solar radiations. The present review studies NEILS as one of the front runner as suitable HTF for solar collectors due to their impeccable thermal properties and the various possible reasons for enhancement in heat transfer properties of NEILS.

The optimal expansion of rocket nozzle has been occasionally attained due to the variation of altitude as the ambient pressure of these altitudes decreases with increase in altitude. Optimal gas expansion occurs only at a particular altitude when the nozzle’s exit pressure (Pe) is equal to the ambient pressure (Pa) of that altitude. There are special altitude adoptable nozzles such as aerospike nozzles, expansion-deflection nozzles and others designed for optimal gas expansion as the altitude increases. However, these nozzles adds weight to the rocket and are expensive for production. This study has been conducted with an experimental Rocket nozzle designed and developed by NSS (Nair Service Society) College of Engineering Palakkad-Kerala, India using computational fluid dynamics to determine the effect of varying the combustion chamber pressure to balance the nozzle exit pressure to the ambient pressure as the rocket ascends in altitudes. From the results obtained, it was observed that there is a conformance of up to twenty three (23) kilometers using the nozzle understudy for which further variation in combustion chamber pressure developed subsonic flows and shock waves in the divergent section of the nozzle. Further analysis showed that the total mass of propellant consumed was 36% per stage engine less than most conventional method of launching rockets engines to orbits. This method of variation of chamber pressure to balance the nozzle exit pressure with the ambient pressure provides potentials for reduction in energy consumption of a rocket.