Papers by Author: Inderdeep Singh

Abstract: There still exist numerous difficulties in generating holes in super alloys, advanced materials and metal matrix composite materials. Electro-discharge drilling (EDD) is a proficient drilling process for the hole making and hole grinding resulting from its characteristics of being a conductive and a thermal process. The EDD process has been investigated with the developed set-up. A EDD set up has been designed and developed as part of the present investigation. The experiments have been conducted on the constant input parameters. This type of process is generally unstable, but its efficiency is very high. The process parameter has been compared with EDM process. The MRR of EDD process has been found to increase as compared to the EDM process. However, this process has a serious problem caused by the tool wear rate, which significantly deteriorates the machining accuracy.

Abstract: The polymer matrix composites (PMCs) are increasingly being used in structural applications owing to their superior mechanical properties. The in-service performance of composite materials requires them to perform under a variety of loading environments. Although a lot of research work has been done towards the mechanical characterization of PMCs, a lot remains to be done in special cases such as characterization of glass fiber reinforced plastics (GFRP) laminates with drilled hole. It is an established fact that drilling in composite laminates causes damage around the drilled hole and the damage influences the mechanical behavior of GFRP laminates under different loading conditions. The present investigation aims at studying the compressive behavior of GFRP laminates with drilled holes. The holes have been drilled at various input parameters (cutting speed, feed rate and drill point geometry) and the effect of these parameters on the compressive behavior of the GFRP laminates has been investigated using statistically designed experiments. It has been found that the drilling parameters significantly affect the compressive behaviour of laminates with drilled holes.

Abstract: Drilling of MMCs is considerably difficult due to the presence of extremely hard reinforcement which causes rapid tool wear and influences the cutting forces and quality characteristics. The present investigation aims at studying the effect of drilling parameters (cutting speed, feed rate and the drill point geometry) on the output responses such as, thrust force (TF), specific cutting pressure (SCP) and surface roughness (SR). Taguchi’s technique has been applied to obtain an optimal setting for drilling process parameters for optimizing the output quality characteristics.

Abstract: Natural fiber based bio-composites are gaining prime importance these days because of their high strength to weight ratio and environmental benefits. An increase in the application spectrum of these materials necessitates cost effective high quality processing in order to meet the stringent design requirements. In the present investigation, fully biodegradable natural fiber (grewia optiva) reinforced poly lactic acid (PLA) composite has been developed. The tensile strength of the composite has been found to increase by 75% of that of the neat polymer. The developed composites have been joined using the adhesive bonding and the microwave joining. The tensile shear strength of the joint has been experimentally evaluated and it has been found that the bond strength of adhesively bonded specimen (4.9% of the parent material strength) is substantially lower as compared to microwave joined specimen (62.85% of the parent material strength). The process of microwave joining has also been simulated using standard Multiphysics software and the results were in close agreement with the experimentally recorded values.

Abstract: The effects of cryorolling (Rolling at liquid nitrogen temperature) and optimum heat treatment (short annealing + ageing) on fracture toughness of 7075 Al alloy are reported in the present work. The Al 7075 alloy was rolled for different thickness reductions (40% and 70%) at cryogenic temperature and its mechanical, fracture toughness properties were studied. The microstructural characterization of the alloy was carried out by using Optical microscopy and Field emission scanning electron microscopy (FESEM). The cryo-rolled (CR) Al alloy after 70% thickness reduction exhibits ultrafine grain structure as observed from its FESEM micrographs. It is observed that the yield strength and fracture toughness of the CR material with 70% thickness reduction have increased by 108% and 73% respectively, compared to the starting material. The CR 7075 Al alloy shows improved fracture toughness and tensile strength due to high dislocation density, grain refinement, and ultrafine-grain (UFG) formation by multiple cryorolling passes. The CR samples were subjected to short annealing for 5 min at 190 0C, 170 0C and 150 0C followed by ageing at 160 0C, 140 0C and 120 0C for both 40% and 70% reduced samples. The combined effect of short annealing and ageing improves the fracture toughness, tensile strength, and ductility of cryorolled samples, which is due to precipitation hardening and subgrain coarsening mechanism respectively. The scanning electron microscopy (SEM) fractographs of the Al 7075 alloy samples reveals that starting bulk Al alloy specimens is fractured in a total ductile manner, consisting of well-developed dimples over the entire surface and dimple size got decreased continuously for cryorolled specimens at different percentage of thickness reduction (40% and 70%) as observed in the present work.