Approaches to the hemming process simulation of an automobile tailgate

Hemming is the process that consists of joining inner and outer panels by bending the edges of the outer panel over the inner one. It is a usual procedure in the automotive manufacturing cycle for side doors, hoods, trunk lids and tailgates. The objective of this paper is to briefly suggest and compare two possible methodologies to simulate the hemming process in an automobile tailgate. In both cases, the simulation tool has been the commercial dynamic explicit F.E.M. code Stampack®. The first method considered the inner panel as a rigid body. In the second approach both inner and outer panels were treated as deformable bodies. The results obtained using the first method show that the non-deformability assumption for describing the reinforcement was not completely wrong. Although not all the details could be captured, quicker results and fair conclusions have been kept. The second method, which assumed both outer and inner panels as deformable bodies, gave very accurate results including the details, but it took more time and effort to be done. The decision to select one approach or another will depend on the purpose of the simulation: preliminary or detailed conclusions.