Vehicle crashworthiness design and analysis by means of nonlinear flexible multibody dynamics

Abstract

The study of crashworthy vehicles' structures requires the use of efficient methods able to provide meaningful results, even with the minimal information available in the conceptual models used in the early phases of the design process. A methodology based in the multibody dynamics of nonlinear flexible systems is presented here for the design and analysis of vehicles in crashworthiness scenarios. While rigid bodies represent most of the vehicle components with their relative motion constrained by kinematic joints, the structural components, such as the front crash-box or the rollbars and A-pillars, are described by means of nonlinear flexible bodies modelled by finite elements. The contact conditions are formulated in terms of continuous force models for rigid body impact, or unilateral constraints for finite element nodal impact. In both cases, the friction forces are also modelled. The methodology is applied to the impact of a vehicle in different crash scenarios. In the process, it is shown that formulation accounts not only for the highly nonlinear variation of the kinematic conditions during impact but also for the occurrence of multiple contacts.