Structural Efficiency and Multi-Functionality of Well-Behaved Nonlinear Composite Structures

复合材料和先进结构预计将成为英国增值制造业经济增长和竞争力的主要驱动力。保持和进一步加强目前的国家竞争优势已被确定为政府的战略优先事项。该奖学金将通过从不同的角度考虑工程结构设计和复合材料来实现这一目标。在构思结构时，通常依赖于成熟的设计原则和强大的分析工具。这可能有几个原因，但缺乏不同方法的经验可能是最重要的。探索“设计师舒适区”之外的机会是一场冒险、昂贵和耗时的赌博，工程公司很少能承担得起。历史上有几个结构设计的例子，尽管处于当前材料技术的最前沿，但却错过了非凡的工程机会。横跨科尔布鲁克代尔附近塞文河的铁桥可能是英国最著名的例子。这座桥于1779年完工，是世界上第一座由铸铁制成的桥梁，并以大量过度设计而闻名，其构思遵循木材而不是金属结构的规则。复合材料是一个现代的例子。它们最显著的特点之一是多功能性，使工程师不仅可以设计结构，还可以设计其组成材料。然而，部分由于其优异的比刚度，通常倾向于使用它们来复制各向同性材料的众所周知的行为，从而错过了利用它们可能提供的许多好处的机会。由于碳纤维复合材料的颜色，这种做法被称为“黑金属”方法。类似地，结构设计通常限于线性区域。换句话说，结构通常被设计成刚性的，并且表现出小的位移，即对所施加的载荷线性响应。在这种情况下，设计方法是建立在几十年经验的基础上的。这确实是工程师的舒适区。设计人员通常避免大位移，因为它们可能导致不必要的形状变化，并触发过渡到非线性状态，可能导致灾难性的，往往是突然的，不受控制的故障。然而，如果我们能够学会控制这种行为，它实际上可以被利用的benefit. This建议的目的是探索的可能性，在结构设计中的非线性响应。主要目标是开发新一代的自适应/多功能结构，在弹性非线性制度和创造新的范式结构效率。其目标是利用复合材料所带来的可能性，并通过消除目前限制结构线性行为的做法所带来的障碍来提供新的设计原则。想象一下，由于非线性刚度特性，飞机机翼或风力涡轮机叶片定制得更轻，并且仍然满足不同操作条件下的要求;建筑物的结构响应仅在受到极端地震载荷时才符合要求，以防止灾难性故障;或者桥梁的刚度在强风情况下增加，防止有害的气动弹性不稳定性。这是我的愿景。这就是复合材料的弹性性能所能提供的，如果我们远离“黑色金属”的方法。

Composite materials and advanced structures are predicted to be major drivers for the growth and competitiveness of UK's value-added manufacturing economy. Maintaining and further enhancing the current national competitive advantage has been identified as a government strategic priority. This fellowship will contribute toward this goal by considering engineering structural design and composite materials in a different light.When conceiving structures, it is common practice to rely on well-established design principles and robust analysis tools. This may be for several reasons, but the lack of experience with different approaches is probably the most important. Exploring the opportunities that are available outside the 'designer comfort zone' is a risky, expensive and time-consuming gamble that engineering companies can rarely afford to take.History shows several examples of structural designs that, despite being at the forefront of current material technologies, missed out on remarkable engineering opportunities. The Iron Bridge, across the river Severn near Coalbrookdale, is probably the most famous case in point in Britain. Completed in 1779, the bridge was the world's first to be made of cast iron and is renowned for being substantially overdesigned, having been conceived following rules for wood rather than metal constructions. Composite materials are a modern example. One of their most remarkable features is the versatility that allows engineers to design not only a structure but also its constituent materials. However, partly due to their excellent specific stiffness, there is often the tendency to use them to replicate the well-known behaviour of isotropic materials, thus missing the opportunity to exploit many of the benefits that they could potentially provide. Owing to the colour of carbon fibre composites, this modus operandi is known as the 'black metal' approach. In a similar way, structural design is normally limited to linear regimes. In other words, structures are often designed to be stiff and exhibit small displacements, i.e. to respond linearly to the applied loads. Under these circumstances design methods are well established and based on decades of experience. This is indeed the engineer's comfort zone. Designers usually avoid large displacements because they may cause unwanted shape changes and trigger the transition to nonlinear regimes, potentially leading to catastrophic and often sudden, uncontrolled failure. However, if we could learn to control such behaviour, it could actually be exploited for a benefit.The aim of this proposal is to explore the possibilities given by nonlinear responses in structural design. The principal objectives are the development of a new generation of adaptive/multifunctional structures working in elastically nonlinear regimes and the creation of novel paradigms for structural efficiency. The ambition is to harness the possibilities presented by composite materials and to deliver new design principles by removing the barriers imposed by the current practice of restricting structures to behave linearly. Imagine aircraft wings or wind turbine blades tailored to be lighter and still meet the requirements imposed at different operating conditions, thanks to nonlinear stiffness characteristics; buildings whose structural response is compliant only if subjected to extreme earthquake loads, so as to prevent catastrophic failure; or a bridge whose stiffness increases in case of strong winds preventing detrimental aeroelastic instabilities. This is my vision. This is what the elastic properties of composite materials can offer, if we move away from the 'black metal' approach.