A self-adaptive energy absorber for improved pedestrian safety and low-speed damage requirements

摘要

Bumper performance under low-speed impacts and pedestrian-to-vehicle impacts are regulated in the United States by Regulation Part 581 and ECE 127/GTR 9, respectively. These regulations possess a contradictory set of requirements. An ideal bumper structure should be stiff for the former scenario while exhibiting a softer response for the latter. Several energyabsorbing structures capable of passively adapting their mechanical responses were investigated using finite element modelling with complementary validation tests. The preferred structure consisted of a rectangular array of trapezoidal cells which buckle under single-cell impacts while resisting lateral deformation and increasing the structural stiffness under large-area impacts. A geometric study of this dissipater demonstrated the potential to increase total energy absorption by 37.3% by adding crossbars between adjacent cells. Additionally, a parametric study identified the upper cell angle and the ratio between wall thicknesses as critical parameters to consider when tailoring the mechanical response.