Crashworthiness of thermoset and thermoplastic fiber-reinforced composites under combined temperature and rate effects

Fiber-reinforced polymer composites are increasingly adopted in energy absorption applications due to their low density and superior energy absorption per unit mass compared to metals. In addition to their lightweight characteristics, these materials offer high specific stiffness, strength, and durability in corrosive environments. This study presents a systematic evaluation of the crashworthiness performance of three commercially available fiber-reinforced composites—glass fiber/polypropylene (GF/PP), glass fiber/polyamide-6 (GF/PA6), and carbon fiber/epoxy (CF/Epoxy)—using a sinusoidal specimen geometry. The novelty of this work lies in the combined investigation of temperature (−40°C to 80°C) and impact velocity (quasi-static to 9.3 m⋅s −1 ) effects on crash energy absorption using standardized, automotive-grade materials. Key crashworthiness metrics—specific energy absorption (SEA), crush force efficiency (CFE), and steady-state crush stress (SSCS)—were used to characterize rate–temperature dependence. The CF/Epoxy system consistently yielded the highest SEA (up to 93 kJ⋅kg −1 ), while the thermoplastic GF/PA6 and GF/PP materials showed competitive SEA values of 88 and 75 kJ⋅kg −1 , respectively. This full-factorial analysis provides critical insight into how thermoset and thermoplastic composites behave under realistic crash conditions and supports ongoing efforts to standardize crashworthiness testing methods for non-tubular composite structures.