Deformation and Failure of Mechanically Adaptive Cellular Materials

具有重要承载功能的人造结构需要费力和昂贵的设计工作，以确保安全和高效的性能。相比之下，在自然界中发现的承重结构会进化并长成合适的结构，因为它们是由适应性材料组成的，比如骨头和木材，这些材料可以根据它们所承载的机械载荷进行自我配置。这种机械适应性的常见例子有：在网球运动员的重负荷球拍臂上观察到的较高的骨密度，由于低重力环境导致的宇航员骨量的损失，或者反映环境压力的年轮厚度的变化。由于对外部环境的机械适应性，骨骼和木材表现出优异的承载能力，重量轻，并且相对于合成材料而言，需要很少的资源来生产（即很少的能源和原材料）。该项目将评估一种以生物为灵感的策略，以制造适应其机械环境的合成材料。该策略将采用纳米制造技术，将结构坚固的纳米复合涂层沉积在多孔泡沫基板上。假设在适当的加工条件下，可以在承受更高载荷的区域沉积更厚的涂层，从而产生具有机械定制微结构的自适应纳米复合材料涂层泡沫。为了确定这些材料的力学行为和性能，将进行一项测试计划，这将在确定均匀泡沫和自适应泡沫的加工、结构和性能之间的相互关系方面发挥不可或缺的作用。研究结果将有助于评估纳米复合涂层泡沫的机械适应性，以及这些材料在预期工程应用中的适用性。理论预测和初步结果表明，高孔隙率、低密度和多功能的特殊机械性能（例如强度和刚度）的组合是可以实现的，使这些材料成为生物医学应用中用作人工组织支架的优秀候选者，以及在重量关键结构中用作轻质承重材料。

Man-made structures with a significant load-bearing function require laborious and costly design efforts in order to ensure safe and efficient performance. In contrast, load-bearing structures found in the natural world evolve and grow into suitable configurations because they are composed of adaptive materials, such as bone and wood, that self-configure according to the mechanical loads they carry. Familiar examples of this mechanical adaptability are the higher bone density observed in the heavily loaded racket-arm of tennis players, the loss of bone mass in astronauts due to a low gravity environment, or variation in annual tree ring thicknesses that reflect environmental stress. As a result of mechanical adaptability to the external environment, bone and wood exhibit excellent load-carrying capacity, are lightweight, and require little in the way of resources to produce (i.e. little energy and raw materials) relative to synthetic materials. This project will evaluate a bio-inspired strategy for fabricating synthetic materials that adapt to their mechanical environment. The strategy will employ a nano-fabrication technique to deposit a structurally robust nanocomposite coating onto a porous foam substrate. Under appropriate processing conditions, it is hypothesised that thicker coatings can be deposited in regions experiencing higher loading, resulting in adaptive nanocomposite-coated foams with mechanically tailored microstructures. A program of testing will be conducted in order to establish the mechanical behaviour and properties of these materials, which will play an integral role in establishing the interrelationship between the processing, structure, and properties of uniform and adaptive foams. The results will enable an assessment of the mechanical adaptability of nanocomposite-coated foams, and the suitability of these materials for anticipated engineering applications. Theoretical predictions and preliminary results suggest a combination of exceptional mechanical properties (e.g. strength and stiffness) with high porosity, low density, and multi-functionality is achievable, making these materials excellent candidates for use as artificial tissue scaffolds in biomedical applications, and as lightweight load-bearing materials in weight-critical structures.