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

弹性失稳是指结构构件的压缩承载能力突然丧失，传统上被认为是破坏极限。然而，不稳定的行为涉及结构几何结构的突然变化和积累的能量的释放。因此，一种新的思维方式正在出现，利用细长结构的不稳定响应来达到似乎正在迅速增加和多样化的目的。圆柱壳是受不稳定性(通常被视为负面特征)影响最大的结构元素之一，但它们的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。研究假设是，圆柱壳可以设计成通过壳体表面的最优几何和材料刚度分布来控制其不稳定响应。这些研究成果将为材料和设备的开发创造新的可能性，这些材料和设备使用不稳定性用于传感、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开发。该项目将允许培训一名博士生，教育和推广部分将扩大本科生和高中生获得该项目核心知识的途径。核心研究想法是，圆柱壳远弹性后屈曲响应的特征可以完全表征、修改和可能定制。所关注的特征不是初始弹性刚度或第一分叉载荷，而是具有多个稳定到不稳定转变的响应、平衡路径加载刚度、临界点转变处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得到扩展，以实现所需的响应，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受压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设计圆柱壳表面的材料和几何特征来定制，从而将传统上被视为不受欢迎的行为转变为在智能材料和结构中使用的机会。这项研究将对控制和设计圆柱壳弹性后屈曲响应的范围和方法产生新的认识，将为可裁剪结构不稳定性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.