Performance of Automotive Composite Bumper Beams and Hood Subjected to Frontal Impacts

Performance of automotive composite bumper beam subjected to frontal impact is presented and discussed in this paper. The aim of this study is to analyze the effect of steel and composite materials on internal energy of the automotive front bumper beam and with respect to pedestrian head injury at the hood. The front bumper beams and hood made of aluminum AA5182, e-glass/epoxy composite and carbon epoxy composite were studied and characterized by impact modeling using LS-DYNA V971, according to United States New Car Assessment Program (US-NCAP) defining the frontal impact velocity and based on European Enhanced Vehicle-Safety Committee. The most important variables of this structure were mass, material, internal energy, and the so-called Head Injury Criterion (HIC). The results are compared with a bumper beam and a hood made of mild steel. The in-plane failure behaviors of the composites were evaluated by using the Tsai Wu failure criterion. LS-DYNA Finite Element Analysis software was used. The results showed that a carbon fiber/epoxy composite bumper can reduce the bumper mass and has the highest value of internal energy followed by the glass fiber/epoxy composite. The FE model of a production hood was introduced and validated. In order to evaluate the protective performance of the baseline hood, the FE models for a 50 percentile of an adult pedestrian dummy were used to impact the hood. It was found that the aluminum AA5182 hood can obviously reduce the Head Injury Criterion (HIC) values compared to the baseline hood. The HIC values of the dummy model were further reduced to much lower than 1000.