Thermoplastic Roof Crush Countermeasure Design for Improved Roof Crush Resistant to Meet FMVSS-216

An automobile is designed to meet numerous impact events, including frontal impact, side impact, rear impact, and roll over. Roof crush resistance is a test defined by Federal Motor Vehicle Safety Standard (FMVSS) 216. The intent of this test is to evaluate the strength of the roof and supporting body structure during a vehicle rollover. Steel countermeasures are typically used as structural-reinforcing elements to the body structure to improve the crush strength of a vehicle roof.

This paper presents a thermoplastic countermeasure (CM) design as a light-weight solution to replace traditional steel countermeasures. Two concepts are discussed in the paper: an all-plastic countermeasure and a plastic/metal hybrid countermeasure consisting of stamped steel with a thermoplastic reinforcing rib structure. Finite Element (FE) methods using LS-DYNA are used to evaluate the performance of these countermeasure concepts. A generic Finite Element model of a sport utility vehicle is used in the analysis. The countermeasure concepts are assembled inside the B-Pillar and the crush strength of the roof is evaluated as per FMVSS-216. This study shows that the thermoplastic countermeasure can be developed with similar stiffness and strength as steel countermeasure, yet with ~40-50% mass savings. This paper provides an overview of the performance for the thermoplastic countermeasures.