Bioinspired composites for the future: sustainable hybrid composites for compression

近几十年来，连续合成纤维增强聚合物在高级结构应用中变得越来越受欢迎。这在很大程度上是因为与金属同类相比，它们具有优越的特性、耐腐蚀性和提高疲劳性能的潜力。然而，随着工程材料的可持续性在日益增长的环境问题中变得越来越重要，人们对天然纤维复合材料(NFC)的兴趣也越来越大，因为它们有可能以更高的可持续性和更低的成本取代合成纤维增强聚合物。NFC还可以提供与E-玻璃纤维相当的特殊性能，E-玻璃纤维是聚合物复合材料最常见的增强纤维之一。尽管如此，NFC在结构和承载应用中的吸收是有限的。造成这种情况的一个关键原因是目前对它们的机械行为的认识存在差距。特别是，公开文献中很少有报告讨论NFC的压缩性能，由此导致的数据稀缺严重降低了人们对NFC用于承载应用的信心。对于连续纤维增强聚合物，纵向压缩性能是设计极限。结构中产生的压缩荷载通常在设计阶段以较高的安全系数考虑。这往往导致过度设计和低效率的结构，进一步强化了研究NFC抗压性能的必要性。该项目的目的是描述NFC的压缩破坏特征，并发展对控制NFC压缩破坏的原理的理解。将研究杂化作为改善机械性能的一种手段。分层和功能分级的应用也将被考虑，因为受生物启发的分层建筑无疑具有潜力来帮助解决因本质上相互冲突的属性需求而产生的挑战。PHD的最终目标是生产和进行宏观测试，以评估NFC组件在结构上的代表性性能。该组件的设计将利用在整个项目中开发的对可持续混合复合材料的新理解。考虑到面向未来的复合材料的重要性，这项工作的发现可能会帮助致力于可持续材料解决方案的行业。具有更高压缩性能的新型材料系统的开发可能会鼓励目前不经常使用复合材料的新行业使用更高性能的材料。由此产生的不那么严格的设计限制可能会使它们能够这样做。感兴趣的行业包括但不限于海洋、风能和汽车行业。

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.