Bekele Adam, Wadee M Ahmer, Phillips Andrew T M
Department of Civil and Environmental Engineering, Imperial College London, London SW7 2AZ, UK.
R Soc Open Sci. 2023 Aug 30;10(8):230762. doi: 10.1098/rsos.230762. eCollection 2023 Aug.
Structural components designed to absorb energy and shield a more valuable structure ideally require mechanical properties that combine a relatively high load-carrying capacity followed by a practically zero stiffness. This ensures that a specified energy quantity may be absorbed within a limited displacement and that any stress transfer to the valuable structure is minimized. Material damage has been historically mobilized to provide such properties, but this obviously renders such components to be single-use. By contrast, mobilization of elastic instability can also provide the desired combination of properties but without necessarily damaging the material. This reveals an intriguing possibility of such components being potentially repairable and theoretically re-usable with no significant loss in performance. A series of analytical, finite-element and experimental studies are presented for a bespoke mechanical metamaterial arrangement that is designed to buckle sequentially and behave with the desired 'high strength-low stiffness' characteristic. It is found that the various axial and rotational stiffnesses associated with the geometric arrangement and its constituent connections may be tuned to provide the desired mechanical behaviour within the elastic range and delay the onset of significant damage, thereby rendering the concept of harnessing instability to be feasible.
旨在吸收能量并保护更有价值结构的结构部件，理想情况下需要具备这样的机械性能：兼具相对较高的承载能力以及几乎为零的刚度。这能确保在有限位移内吸收特定能量，并将传递到有价值结构上的应力降至最低。过去一直通过材料损坏来实现这些性能，但这显然使此类部件成为一次性使用的。相比之下，利用弹性失稳也能提供所需的性能组合，且不一定会损坏材料。这揭示了此类部件可能可修复且理论上可重复使用而性能无显著损失的有趣可能性。针对一种定制的机械超材料结构进行了一系列分析、有限元及实验研究，该结构设计为依次屈曲并表现出所需的“高强度 - 低刚度”特性。研究发现，与几何结构及其组成连接相关的各种轴向和旋转刚度可进行调整，以在弹性范围内提供所需的力学行为，并延迟重大损坏的发生，从而使利用失稳的概念变得可行。
