Analysis of the Crashworthiness of Novel Flax‐Fiber Hybrid Reinforced Three‐Dimensional Woven Composites

ABSTRACT This study investigates the impact crashworthiness performance of flax‐fiber reinforced three‐dimensional (3D) composites through a comprehensive experimental program. Composite panels with tailored 3D woven architectures were manufactured using a resin infusion process and subjected to in‐plane crashworthiness tests. The impact response was evaluated in terms of peak load, load–displacement characteristics, specific energy absorption (SEA), and post‐impact damage morphology. High‐speed data acquisition and post‐test inspections were employed to identify dominant failure mechanisms, including fiber fracture, matrix cracking, yarn pull‐out, and through‐thickness damage evolution. The role of 3D weaving parameters, particularly binder yarn configuration and fiber volume and weight fraction, on impact resistance and crash energy absorption was systematically assessed. Novel impact parameters were developed to more clearly display the effect of the architecture. Experimental results reveal that the presence of through‐thickness reinforcement delays damage initiation, suppresses delamination, and promotes progressive crushing under impact loading. Compared with the non‐reinforced two‐dimensional flax composite, the most effective 3D architecture increased the SEA from 39.5 ± 3.5 kJ/kg to 62.3 ± 3.4 kJ/kg, corresponding to a maximum improvement of approximately 57%, while the symmetric architecture achieved a 48% increase. The simple flax architecture, however, led to a 15% decrease in SEA, indicating that the crashworthiness improvement is governed not only by the presence of through‐thickness binders but also by their architecture. The findings demonstrate that properly designed 3D woven flax‐fiber architectures can significantly enhance impact crashworthiness and support their potential application in lightweight, sustainable structural components subjected to dynamic loading conditions.