Date of Award
Mechanical, Automotive, and Materials Engineering
Bumper, Pedestrian protection, Self-adaptive
Bumper design regulations for low-speed vehicular impacts (Part 581, Bumper Standard, formerly FMVSS 215) and high-speed pedestrian impacts (ECE 127/GTR 9) possess a contradictory set of requirements. Essentially, an ideal bumper structure should be stiff under low-velocity vehicular impacts while exhibiting a softer response when impacting pedestrians at elevated velocities to satisfy both regulations. A series of energy absorbing structures capable of passively adapting their mechanical responses based on the loading conditions were investigated using finite element modelling tools which were validated to a series of experimental testing observations. The preferred structure consisted of a rectangular array of trapezoidal cells which buckle under single-cell impacts while resisting lateral deformation and artificially increasing the overall stiffness under large area impacts. A geometric study of this dissipater demonstrated the potential to increase total energy absorption by 37.3% by adding thin-walled crossbars at the bases of adjacent cells. Additionally, a parametric study identified a combination between upper cell angle and the ratio between the wall thicknesses as the most critical parameter to consider when tailoring the overall mechanical response.
Wu, James, "A SELF‐ADAPTIVE ENERGY DISSIPATION STRUCTURE FOR LOW SPEED IMPACT AND PEDESTRIAN PROTECTION" (2018). Electronic Theses and Dissertations. 7586.