Defence Research and Development Laboratory

About: Defence Research and Development Laboratory is a facility organization based out in Hyderabad, India. It is known for research contribution in the topics: Mach number & Turbulence. The organization has 404 authors who have published 420 publications receiving 4183 citations. The organization is also known as: DRDL.

Performance Evaluation of Rotary EDM by Experimental design Technique

Abstract: This paper presents an experimental design to study the performance of rotary electro-discharge machining (EDM). Scientific investigations have been carried out to find the effect of various EDM parameters. Titanimn alloy and die steel workpieces were machined with copper-tungsten tool electrode. The response surface technique has been adopted to compare the performance of rotary EDM, since such technological surfaces serve as an objective criteria to compare EDM systems. Moreover, such a surface and its response function serve as a mathematical model of the process. The analysis of the results was based on standard statistical techniques. The response surfaces and the corresponding response functions were determined for the machining indices for metal removal rate, surface finish, micro-hardness, etc. All the calculations were carried out through a computer programme specially developed for this purpose."

Hypersonic flight vehicle trajectory optimization using pattern search algorithm

Abstract: In this work, trajectory optimization of an aerodynamically controlled hypersonic boost glide class of flight vehicle is presented. In order to meet the mission constraints such as controllability, skin temperature, and terminal conditions etc., the trajectory is optimized using a pattern search algorithm with the lift to drag (L/D) ratio as a control parameter. It is brought out that the approach offers a viable tool for optimizing trajectories for the considered class of vehicles. Further, the effects of the constraints on trajectory shape and performance are studied and the analysis is used to bring out an optimal vehicle configuration at the initial stage of the design process itself. The research also reveals that the pattern search algorithm offers superior performance in comparison with the genetic algorithm for this class of optimization problem.

Dissimilar Welding of Maraging Steel (250) and 13-8 Mo Stainless Steel by GTCAW, LBW and EBW Processes

Abstract: The frequently used aerospace materials, i.e., ultra-high-strength maraging steel (250) and corrosion-resistant 13-8 Mo stainless steel in the solution-annealed and cold-worked condition, have been joined by three fusion welding processes, namely interpulse TIG welding, and high energy density fusion processes like electron beam welding (EBW) and laser beam welding (LBW). The interpulse TIG welding process was carried out by using W2 grade maraging steel filler wire. The dissimilar joints were welded by EBW and LBW processes without any filler wire. All the dissimilar welded joints were characterized by microstructural observations and validated by mechanical properties in the as-welded as well as precipitation-hardened conditions after welding. The weld microstructures and microhardness profiles were correlated to the tensile strength of weld. Electron beam welded joint with precipitation hardening after welding, i.e., soaking at 510 °C and subsequent air cooling, demonstrated the superior mechanical properties among all the welds.