Influence of Geometrical Shape on the Impact Behavior of Flax and Hybrid Composites: Experimental and Numerical Study

Abstract

Growing environmental concerns have driven advancements in green composites to reduce the ecological impact across industries, including automotive. Composite materials reinforced with natural fibers, such as flax, offer a sustainable alternative to traditional materials. However, they still face limitations in mechanical performance and durability compared to synthetic fibers like carbon. In this context, hybridization offers a promising strategy for reducing the carbon footprint while preserving material performance. This study begins by investigating the impact properties of carbon/ and flax/epoxy laminates through a combined experimental and numerical approach. Specifically, the in-plane crashworthiness of flat samples is evaluated to determine their energy absorption capabilities and to extract material parameters for modeling using LS-DYNA software. In addition, both experimental and numerical investigations are conducted on the axial crushing behavior of circular tubes, including also hybrid carbon-flax composites, to further assess crashworthiness and examine the influence of the geometric shape of components. Macro-scale and meso-scale numerical models are developed and validated against experimental results. The meso-scale models, in particular, demonstrate a superior ability to accurately replicate load-displacement responses and failure mechanisms, confirming their reliability in predicting the behavior of these materials under impact conditions.