Interpretation of Deformation Pattern in Automotive Rails in Frontal Impact

Two barriers are commonly used to evaluate the response of a vehicle in a frontal impact: the rigid barrier and the offset deformable barrier. They produce different deformation patterns, which opens up the possibility that at least one of them does not represent real world crashes. One possible cause of the difference is that an impact into a rigid barrier generates significantly greater stress waves than impacts in the real world resulting in final deformation patterns that are different from those seen in the field. To evaluate this conjecture models of two types of rails each undergoing two different types of impacts, are analyzed using an explicit dynamic finite element code. Results show that the energy perturbation along the rail depends on the barrier type and that the early phase of wave propagation has very little effect on the final deformation pattern. This implies that in the real world conditions, the stress wave propagation along the rail has very little effect on the final deformed shape of the rail.