Crash Performance of Additively Manufactured Tapered Tube Crash Boxes: Influence of Material and Geometric Parameters

Crash boxes play a crucial role in mitigating force during vehicle collisions by absorbing impact energy. Additive manufacturing (AM), particularly Fused Deposition Modeling (FDM), has emerged as a promising method for their fabrication due to its design flexibility and continuous advancements in material development. This study investigates the crash performance of tapered crash box configurations, each manufactured using two FDM materials: Carbon Fiber-Reinforced Polylactic Acid (PLA-CF) and Polylactic Acid Plus (PLA+). The specimens vary in wall thickness and taper angles to evaluate the influence of geometric and material parameters on crashworthiness. The results demonstrated that both specific energy absorption (SEA) and crush force efficiency (CFE) increase with wall thickness and taper angle, with PLA-CF consistently outperforming PLA+ in both metrics. ANOVA results showed that wall thickness is the most influential factor in crashworthiness, accounting for 73.18% of SEA variation and 58.19% of CFE variation. Taper angle contributed 13.49% to SEA and 31.49% to CFE, while material type had smaller but significant effects, contributing 0.66% to SEA and 0.11% to CFE. Regression models were developed based on the experimental data to predict SEA and CFE, with a maximum absolute percentage error of 4.97%. These models guided the design of new configurations, with the optimal case achieving an SEA of 32.086 ± 0.190 kJ/kg and a CFE of 0.745 ± 0.034. The findings confirm the potential of PLA-CF in enhancing the energy-absorption capability of crash boxes, particularly in tapered designs.