Property optimized energy absorber for automotive bumpers utilizing multi-material and structural design strategies
Komal Chawla, Ahmed Arabi Hassen, Nikhil Garg, Deepak Kumar Pokkalla, Desheng Yao, Tyler C. Smith, Brittany Rodriguez, Brandon White, Xiaolin Zheng, Ellen Lee, H. Felix Wu, Seokpum Kim
Abstract
• Automotive bumper energy absorber combining optimized lattice structures and multi-material blends. • Requiring both low-speed collision performance and high-speed pedestrian impact protection. • 576 finite element simulations, exploring various combinations of lattice configurations, material blends, and material placements. • Optimized design and material combination providing a 68 % increase in energy absorption while achieving a 70% decrease in peak force. This study proposes a novel design for automotive bumper using optimized lattice structures and multi-materials to balance low-speed collision and high-speed pedestrian impact performance. Different blends of 20 % carbon fiber-reinforced acrylonitrile butadiene styrene with thermoplastic polyurethane were used to tailor material properties. The energy absorber features lattice structures with customized mechanical responses, created by varying the incline angle θ from 0 to 180°. We conducted 576 finite element simulations on a half-scale model to optimize energy absorption and stiffness, leading to 66 optimized designs that met both low-speed and high-speed impact criteria. Two sub-scale optimized energy absorbers with different peak forces—both meeting low-speed impact requirements—were 3D printed and validated through drop-weight testing. The one with lower peak stress demonstrated a more compliant response, exhibiting approximately 90 % lower initial peak force and an increase in energy absorption of around 33 % (from 24 J to 32 J). Compared to the baseline triangular lattice, the optimized absorber increased energy absorption by 68 % from (19 J to 32 J) and reduced peak stress by 70 %. It also showed near-complete recovery with minimal fractures, making it suitable for repeated use. This design improves safety while offering a lightweight, durable, and cost-effective bumper system.