Bioinspired composites for the future: sustainable hybrid composites for compression

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In recent decades, continuous synthetic fibre-reinforced polymers have become increasingly popular for advanced structural applications. This is largely due to their superior specific properties, corrosion resistance and potential for enhanced fatigue performance when compared to their metallic counterparts. However, with the sustainability of engineering materials becoming an increasingly important consideration amid growing environmental concerns, interest in natural fibre composites (NFCs) is growing due to their potential to replace synthetic fibre-reinforced polymers with improved sustainability and at a lower cost. NFCs can also offer specific properties comparable to E-glass fibre, which is one of the most common reinforcing fibres for polymer composites. Despite this, the uptake of NFCs for structural and load-bearing applications is limited. One key reason for this is the current gap in knowledge regarding their mechanical behaviour. In particular, very few reports in open literature discuss the compressive performance of NFCs, and the resulting scarcity of data severely degrades confidence in the use of NFCs for load-bearing applications. The longitudinal compressive performance is design-limiting for continuous fibre-reinforced polymers. The compressive loads that arise in structures are typically accounted for at the design stage with higher safety factors. This often results in overdesigned and inefficient structures, further solidifying the need for investigating the compressive performance of NFCs. The aim of the project is to characterise the compressive failure of NFCs and develop an understanding of principles that govern the failure of NFCs in compression. Hybridisation will be investigated as a means to improve mechanical performance. The application of hierarchical and functional grading will also be considered since there is undoubted potential for bioinspired hierarchical architectures to help resolve the challenges that arise from intrinsically conflicting property demands. The end goal of the PhD is to produce and conduct macro-scale testing to assess the structurally representative performance of an NFC component. The design of this component will utilise the new understanding of sustainable hybrid composites developed throughout the project. Given the importance of future-proofing composites, the findings of this work could help industries working towards sustainable material solutions. The development of novel material systems with improved compressive performance may encourage new industries, which currently do not routinely use composites, to use higher-performance materials. They may be enabled to do so by the resulting less stringent design limits. Industries of interest include but are not limited to, the marine, wind energy and automotive sectors.