Dynamic compressive behavior of woven flax-epoxy-laminated composites

Currently, natural fiber-reinforced composites serving as building blocks for structural parts have attracted increasing attention in the automotive industry due to demands of energy and environmental sustainability. In this study, woven flax-epoxy-laminated composites were fabricated using vacuum-assisted resin infusion. The in-plane and out-of-plane compressive behavior of the fabricated specimens was experimentally studied from quasi-static to dynamic loading. Dynamic experiments revealed remarkable strain rate sensitivity for both loading directions. The ultimate stress and specific energy absorption for in-plane loading increased by 49.6% and 30.4%, respectively, as the strain rate varied from 3.0 × 10−3/s to 2.8 × 103/s, while increased by 61.2% and 25.9% for out-of-plane loading cases. Final deformation photographs, high-speed camera images, and scanning electron micrographs of the flax fiber composites clearly illustrated their damage evolution and various failure mechanisms, including fiber buckling, matrix crack, fiber pull out, and fiber fracture at different strain rates and loading directions. Finally, a detailed computational model considering damage evolution and strain rate is established and verified by experiments for in-depth investigation. These results may serve as a guide for the future application of natural fiber-reinforced composites in the automotive industry.