Tailoring of the Elastic Postbucking Response of Cylindrical Shells: A Route for Exploiting Instabilities in Mechanical Systems

弹性失稳是指结构单元压缩承载能力的突然丧失，传统上被认为是一种破坏极限。然而，不稳定行为涉及结构几何形状的突然变化和累积能量的释放。因此，一种新的思维方式正在出现，即利用细长结构的不稳定响应来实现似乎正在迅速增加和多样化的目的。圆柱壳是受不稳定性影响最大的结构元件之一（通常被视为负面特征），但其几何形状为控制其不稳定响应提供了独特的机会，可以以可恢复的方式显示多个不稳定转变。研究假设可以设计出通过壳体表面最优的几何和材料刚度分布来控制其不稳定响应的圆柱壳。研究结果将为材料和设备的开发创造新的可能性，这些材料和设备将不稳定性用于传感、驱动、控制、能量收集和能量耗散等应用；这些进步反过来也可以促进新型智能、活性和多功能材料和结构的发展。该项目将培养一名博士生，教育和推广部分将扩大本科生和高中生获得该项目的核心知识的机会。研究的核心思想是圆柱壳的远弹性后屈曲响应特征可以被充分表征、修改和定制。研究的特征不是初始弹性刚度或第一次分岔载荷，而是多次稳定到不稳定转变的响应、平衡路径加载刚度、临界点转变时释放的动能以及循环加载过程中的耗散能量。拓扑和形状优化技术将扩展到实现期望的响应，实验将验证计算设计和基于有限元的模拟。将开发具有可控弹性后屈曲行为的轴向载荷圆柱体的分析和设计框架。关键的创新将是证明圆柱壳的弹性后屈曲响应可以通过壳体表面的材料和几何特征的设计来定制，从而将传统上被视为不受欢迎的行为转变为智能材料和结构的使用机会。该研究将为控制和设计圆柱壳弹性后屈曲响应的程度和方法提供新的知识，为结构失稳定制的使用提供新的概念和指导。

Elastic instability, which refers to the sudden loss of compression load carrying capacity of a structural element, is traditionally considered a failure limit. Yet, unstable behavior involves a sudden change of the structure's geometry and the release of accumulated energy. Thus, a new way of thinking is emerging for using the unstable response of slender structures for purposes that seem to be rapidly increasing and diversifying. Cylindrical shells are among the structural elements most affected by instabilities (commonly seen as a negative trait) but their geometry provides unique opportunities for controlling their unstable response, which can display multiple unstable transitions in a recoverable manner. The research hypothesis is that cylindrical shells can be designed such that their unstable response is controlled through optimal geometric and material stiffness distributions on the shell surface. The research findings will create new possibilities for the development of materials and devices that use instabilities for applications such as sensing, actuation, control, energy harvesting, and energy dissipation; advances that in turn could also facilitate the development of novel smart, active and multifunctional materials and structures. The project will allow training of a Ph.D. student and educational and outreach components will broaden access to the project's core knowledge to undergraduate and high-school students.The core research idea is that the features in the far elastic postbuckling response of cylindrical shells can be fully characterized, modified, and potentially tailored. The features of interest are not the initial elastic stiffness or the first bifurcation load, but a response with multiple stable to unstable transitions, the equilibrium path loading stiffnesses, the released kinetic energy at critical point transitions, and the dissipated energy during cyclic loading. Topology and shape optimization techniques will be expanded to achieve the desired response and experiments will validate computational designs and finite-element based simulations. Analysis and design frameworks will be developed for axially loaded cylinders with controllable elastic postbuckling behavior. The key innovation will be proving that the elastic postbuckling response of cylindrical shells can be tailored through the design of material and geometric features on the shell's surface, thus transforming a behavior traditionally seen as undesirable into an opportunity for use in smart materials and structures. The research will generate new knowledge on the extent and means to control and design the elastic postbuckling response of cylindrical shells, which will provide new concepts and guidance for the use of tailorable structural instabilities.