Roof Deformation in Vehicle Rollover: The Case for Including an Energy Criterion in Vehicle Crashworthiness Evaluation

Abstract

Vehicle rollover crashes are a serious public health concern in the United States with far reaching socioeconomic impacts. Rollovers occur in only 3% of crashes, but account for a disproportionately high number of the serious traffic injuries and fatalities, 30% in 2008 (NHTSA, 2010). Currently in the United States, the only federal motor vehicle safety standard (FMVSS 216) governing vehicle crashworthiness for rollover is based on a quasi-static roof crush test that requires each vehicle to have a minimum strength-to-weight ratio (SWR>3.0). FMVSS 216 has been criticized for not accurately representing vehicle structural response to real-world dynamic rollover crashes, as well as for the choice of peak SWR as the evaluation metric. This thesis is a collection of three studies aimed at evaluating the relationships between force, energy, and deformation in rollover crashes. It is hypothesized that for a vehicle in a single roof-to-ground rollover impact that greater total kinetic energy at touchdown will result in larger structural deformation, and that an increase in the peak SWR of the vehicle will not reduce deformation if it is not accompanied by a similar increase in energy absorption.