From Tortoise Exoskeletons to Engineering: Innovating High-Impact Bio-Composites with Rigid-Flexible Grid Structures

Abstract

The pursuit of advanced materials that meet the rigorous requirements for strength and toughness, particularly in critical sectors such as automotive, rail transit, aerospace, and marine engineering, is often constrained by the inherent brittleness and relatively lower mechanical strength of natural fiber-reinforced polymer composite (NFPCs). In response to this challenge, our research introduces a novel composite design inspired by the multi-layered, rigid-flexible architecture of turtle exoskeletons. An innovative bio-composite (BPC-CFMP-F) was developed by integrating a continuous grid composed of high-strength, high-rigidity carbon fabric mesh prepreg alongside high-elasticity, high-toughness cast film (MSF) into bamboo fiber/polyethylene composites via coextrusion. This design significantly enhances the composite's impact resistance and strength. Compared to the unreinforced controls, BPC-CFMP-F exhibited a significant increase in peak impact force resistance by up to 108.7%, while maintaining superior structural integrity under various impact energies, as evidenced by significantly reduced damage areas and indentation depths. Remarkably, the post-impact flexural properties of BPC-CFMP-F astonishingly exceeded those of the controls prior to impact. Additionally, our investigation into the stress distribution and damage mechanisms within these composites under impact utilized simulation techniques, providing insights that closely matched our experimental findings. This convergence of experimental and simulated data validates the effectiveness and our biomimetic design and its potential to revolutionize the application scope of NFPCs. By incorporating a rigid-flexible configuration inspired by natural resilience, we pave new avenues for enhancing traditional NFPCs, making them suitable for high-demand applications where enhanced load-bearing capacity and impact resistance are crucial.

Keywords: Natural fiber-reinforced polymer composites, Low-velocity impact, Turtle exoskeletons-inspired, Carbon fabric mesh, Impact resistance