Optimisation of Important Factors Influencing Spring-back after Sheet Metal Forming

Fabricating parts such as structural members of automobiles are achieved by using sheet metal forming technique. Light weight high strength materials are preferable to minimise the fuel consumption and therefore reducing the emissions. However, fabricating such materials are usually associated with some defects. One of the most announced phenomenon is called Spring-back; the deviation in specimen geometry subsequent to forming due to elastic recovery. The aim of the current research is to assess the effect of main forming process parameters on the Spring-back level. The U-drawing process was studied in this work, since this process supports more complex sheet metal forming operations. A reliable test rig for such operation was created and 3D finite element model was developed to simulate the process. The simulations for four different material were validated. An acceptable agreement between the simulations and experiments results were obtained, however, the high strength galvanised steel shows disagreement results. Parametric study was concocted to evaluate the influence of several parameters on the Spring-back magnitude. Finally, an optimisation method was developed to find the optimum parameters combination to reduce Spring-back level and successfully utilised to optimize the process parameters for the different materials studied