Executive Summary : | Tailor-welded blanks (TWB) have numerous benefits over conventional blanks for manufacturing automobile sheet metal components, including more product design freedom, improved structural rigidity, and improved crash behavior. Tailor-welded blanks (TWB) usage also decreases manufacturing costs, vehicle weight (making them more environmentally friendly), and removes post-forming welding activities. However, one of the biggest issues with TWBs is their low formability in conventional sheet metal forming techniques. Shock tube forming, which uses shockwaves to deform a blank, is one of the possible means for improving TWB’s formability. A pneumatically operated device is a shock tube, in which high-pressure driver segment and a low-pressure driven section are divided by a plastic or metallic diaphragm. The diaphragm ruptures when the pressure differential reaches a certain level, and a shockwave is produced when gas is released suddenly. The sheet at the end of the tube gets struck by the high-velocity shockwave as it travels down it. Most of the work on analysing the formability aspects of monolithic sheets under biaxial tension has been performed using shock tube forming process. However, literature on formability prediction of TWBs using using shock tube forming process is scarce. The initial step in this proposal is to design and create a shock tube facility for evaluating the deformation behaviour of TWBs under extremely high strain rates. In the second section of the work, formability characteristics of TWBs made of DC01 grade steel with various thickness combinations will be investigated at extremely high strain rates. Moreover, a numerical investigation employing various hardening laws and advanced yield criteria (such as Barlat's 2000 yield criterion (Yld2000-2d)) will be conducted, and comparisons with experimental data will be performed. At IIT Delhi, conventional forming tests will also be carried out as part of the third section of the project in order to compare the output with the outcomes of the shock tube forming. The service life of parts, particularly in the automobile sector, is significantly influenced by residual stresses in components made using sheet metal. The fourth section of the work will involve the numerical prediction of residual stresses in shock tube forming simulations of laser-welded IF steel sheets, followed by experimental validation using the x-ray diffraction technique. The suggested research will assist automakers in increasing the predictability of automobile components manufactured using TWBs at extreme high strain rates. |