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Carbon fibre reinforced plastics (CFRP) and titanium (Ti) stacks have been steadily replacing metals as choice for engineering materials in aerospace applications. Although materials can be manufactured separately and stacked together to attain a near-net shape, it still involves post processing operations such as trimming and drilling. In order to drill holes efficiently without defects (delamination, circularity, variation in hole diameter) in the CFRP/Ti stacks, it is essential to understand the machining behavior of stacks. An experimental study on the drilling of CFRP/Ti stacks was conducted using K20 carbide drill. The drilling characteristics were evaluated for drilling force and torque, delamination in CFRP, drilled-hole quality (hole diameter and circularity) and exit burr height in Ti. This paper describes an attempt made to maximize the hole quality parameters by employing multi-objective optimization using weighted sum method.

Magnesium is very attractive material with the combination of good strength, low weight and low corrosiveness. The uses of its alloy materials through various manufacturing methods are found in aerospace and automotive components in common inspired by weight restriction and reduction. Magnesium alloys are very light, strong and also possesses high thermal radiation properties. The high performance magnesium alloys with high temperature characteristics, pressure tightness and their ability to produce complex shapes makes it suitable in producing different aircraft components. As, the whole world is moving into the future of electric mobility through e-bikes and cars, research is already into the choice of materials for its components. As weight to power ratio is the major design issue in e-vehicles, a project to optimize a perfect material for the chassis becomes essential in the development of e-mobility. This project is about determining the strength capability of magnesium alloys for suitability as a material in electric vehicle chassis that wants for high strength and low weight. Thus, magnesium alloys like AZ91D and AZ31B are chosen as per ASTM standards for a stress analysis into manufacturing of electric vehicle chassis. The chassis of electric vehicle is designed as per its requirements taking into consideration of present development and a static and dynamic analysis is being carried out using a suitable finite analysis package for determining an optimum material.

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The objective of the study is to reduce the stress created in the root fillet region as the maximum stress concentration in gears occurs in the fillet. Therefore, stress relieving features have been created at an offset distance from the root fillet to reduce the stress. A Spur gear with involute profile is taken for the study. The application taken for the study is the gear used in terrain vehicles. The material of the gear is EN-353 grade Steel. Based on the compressive strengths and bending strengths, the spur gear is designed to the required application. The gear is modelled using the specifications obtained from the design calculations. The forces acting on the gear is calculated considering the application in which it is used. The gear is then analysed using the ANSYS WORKBENCH 14.0 software. It has been found that the maximum stress acts near the root fillet region. Hence, stress relieving features of circular and elliptical shapes are created at an offset distance from the root fillet. It has been found that the gear with elliptical stress relieving hole has the minimum stress than those of gears with other combinations. The next objective which is to reduce the mass of the gear is done by creating larger holes in the lower stress regions of the gear. The mass reducing features are created in the gears with stress relieving features and each gear has been subjected to analysis for the minimum amount of stress. It has been found that the value of stress is less in the gear with mass reducing holes but with no stress relieving feature. Thus, the stress acting on the root fillet region has been reduced by 20% by creating circular and elliptical holes. The other objective of mass reduction is satisfied by creating larger holes.