Shape optimization of bumper beams under high-velocity impact loads

• Optimal cross-sectional shapes of a bumper beam are investigated for maximum crashworthiness.
• A lumped-parameter model is developed to mimic the behavior of the main vehicle body.
• Energy absorbed by the deformable barrier is accounted for by a correction factor on vehicle mass.
• For different weighing factors in the objective function, different optimal shapes are obtained.
• Low-velocity requirements are also satisfied.

Box-shaped bumper beams mounted on vehicles serve as shock absorbers in a potential crash. In this study, their optimal shape design is investigated. The objective is to maximize the crashworthiness of the beam. The crash phenomenon in standard tests is simulated in which the vehicle hits a deformable barrier with 40% offset by 64 km/h speed. The bumper beam and the brackets supporting the beam are modeled as deformable bodies in full detail. For the rest of the car, a lumped parameter model is developed. The crash event is simulated using explicit finite element method. The design variables are the parameters defining the cross-sectional shape of the beam. The beam is optimized using a hybrid search algorithm combining Genetic and Nelder & Mead algorithms. The results indicate significant improvement in the crashworthiness of the bumper beam currently in-use. Resistance to low-velocity impact is also improved.