Simulating the Complete Forming Sequence for a Roll Formed Automotive Bumper Beam

As part of the development of a new automotive bumper beam, a complete simulation of the entire forming process was carried out using LS-DYNA. The material for the beam was an ultra high strength steel presenting many challenges for the forming process. The sequence of forming operations was roll-forming (including forming a sweep in the initially straight roll-formed section), local annealing, forming of an initiator in the wall of the section and then crushing the end of the previously rolled section. The forming results (geometry, thinning and work hardening) were all transferred to the simulation of the bumper performance under various impact conditions. The paper describes the development of certain novel simulation techniques, particularly for the roll-forming for which the implicit analysis options of LS-DYNA were used, representation of the annealing process, as well as the method in which data was transferred between the various simulations. Above all, we describe how the simulations were used to guide the design of the bumper beam system up to the point of prototype manufacture and test.