Progress in press forming computer aided analysis for high strength steel sheet applications

The development of press-forming analysis technologies is important to expand the application of high strength steel sheets to automotive body structures. In general, there are various problems in the forming process of high strength steel sheets. In this study the improvements in the prediction accuracy of stretch-flange-fracture and springback were especially focused. In terms of the prediction accuracy of stretch-flange-fracture, a new stretch-flange-fracture prediction technology was developed based on a maximum principal strain gradient. It enables the accurate prediction of stretch- flange-fracture in press-forming of practical parts. On the other hand, springback prediction technologies were developed to solve springback problems. It is very important to clarify the root cause of springback in order to control. Therefore, a new method of springback factor analysis was developed, which can extract the areas and residual stresses which have major impacts on springback at press-forming.