Improved numerical constraint disposal method for process conditions in sheet metal forming simulation

The constraint force generated by process conditions, such as drawbead resistance and boundary friction are generally considered as positive force in dynamic explicit finite element method, which actually are not in accord with realistic effect. A constraint disposal method for constraint force in sheet metal forming simulation was proposed using linear spring element to build more accurate numerical model of process conditions such as blank-holding force, drawbead resistance and boundary friction, to represent the passive and synchronous effect of constraint force. Drawing process of an underbody cross member panel was simulated. The prediction of thickness strain distribution was shown to be in very good agreement with experimental result.