Crash Performance of Steel, Aluminum and Carbon Fiber Composite Bumper Beams with Steel Crush Cans 2021-01-0286

In frontal collision of vehicles, the front bumper system is the first structural member that receives the energy of collision. In low speed impacts, the bumper beam and the crush cans that support the bumper beam are designed to protect the engine and the radiator from being damaged, while at high speed impacts, they are required to transfer the energy of impact as uniformly as possible to the front rails that contributes to the occupant protection. The bumper beam material today is mostly steels and aluminum alloys, but carbon fiber composites have the potential to reduce the bumper weight significantly. In this study, crash performance of bumper beams made of a boron steel, aluminum alloy 5182 and a carbon fiber composite with steel crush cans is examined for their maximum deflection, load transfer to crush cans, total energy absorption and failure modes using finite element analysis. All three beams have the same design features, but their thickness is varied to maintain the same bending stiffness. The crush can design is the same for all three beams. Two different impact conditions were used. In 16.4 kmph impact, all three beams show similar total energy absorption; however, in 55 kmph impact, the steel beam has the highest energy absorption. In terms of energy absorption per unit mass, the carbon fiber composite beam shows significantly higher energy absorption per unit mass compared to the other two beams.