On the dynamic effects of explicit FEM in sheet metal forming analysis

This study is concerned with dynamic effects. when we use explicit FEM for sheet metal forming analysis. Since sheet metal forming is a quasi-static process, time scaling and mass scaling techniques have been widely used in order to save computation time. However, to define suitable scale factor still requires several trials. In this study, an internal energy error estimate which indicates accumulated incremental errors due to dynamic effects is suggested. This estimate is applied to each subdomain to consider the locality of deformation. Draw bending problem is analyzed to show the effectiveness of the suggested method. An analytic solution is derived for simplified draw bending to compare with the computed results. The cause of stress error in this problem is investigated and the method to reduce the stress error is suggested. Finally, the suggested method is applied to S-rail benchmark test.