A two degrees of freedom model–based optimization method for occupant restraint systems in vehicle crash

This paper presents a two degrees of freedom model–based optimization method for occupant restraint systems (ORS), applied before the finite element analysis in a vehicle crash. The method considers the effects of restraint systems (seatbelt, airbag, seat, and knee baffle) on the occupant and establishes the analytical models of them. The method reveals the effect essence of the ORS and takes the occupant response as the target to optimize the restraint system parameters rapidly. The multi-rigid body model of a Toyota Camry vehicle is established to verify the validity and reliability of two degrees of freedom model (TDFM). Comparing the results of the two models, the trends of acceleration-time curves are consistent, and the 85% errors of occupant responses are within 20%. Then, the practicality and effectiveness of the optimization method are confirmed by the instance of Camry ORS. The errors of results solved by optimization and the MADYMO model are all less than 20%. The optimization method can be used to provide an initial parameter range for the finite element simulation to improve the efficiency of the traditional optimization process.