Crash Mode Analysis of Vehicle Structures Based on Equivalent Mechanism Approximations

This paper presents a method for crashworthiness design of vehicle structures based on analyses of crash mode (CM), a sequence of axial crushing, twisting, and transversal bending during a crash event. The method emulates a process commonly called “mode matching” by vehicle designers, where the crash performance of a structure is improved by manually modifying the design until its CM matches the one the designers deem as optimal. Instead of relying on the insight of experienced designers, an optimal CM of a structure is identified via the numerical sampling of the design space of an “equivalent” mechanism, which approximates the structure as a network of rigid beams joined by prismatic and revolute joints with special nonlinear springs. The sampled designs of the mechanism are first classified according to their CM, and a finite element (FE) model of a baseline design is then manually modified to match the best CM. A case study on a 2D vehicle front substructure subjected to full-lap crash demonstrated that the method yield a better design than numerical optimization with a far less number of nonlinear FE simulations.