发表机构
Politecnico di Milano; Imperial College London（米兰理工大学; 帝国理工学院）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究开发了解析框架预测各向同性五模式晶格的屈曲极限，考虑全局与局部失稳机制，并通过数值模拟验证，揭示了接近五模式极限与屈曲抗力间的权衡及连杆设计的优化潜力。
AI 中文摘要
五模式晶格是一种架构材料，其弹性响应由单一变形模式主导。然而，其他变形模式的低刚度可能导致在压缩预应力下稳定性受限，从而限制其力学性能。在本工作中，我们开发了一个通用解析框架，用于确定具有通用连杆几何形状的预应力二维和三维各向同性五模式晶格的屈曲极限。考虑了两种不同的失稳机制：与有效介质稳定性丧失相关的全局失稳，以及与晶格胞尺度有限波长模式相关的局部失稳。推导了相应临界压力的闭式表达式，屈曲极限取两者中的较低值。解析预测通过不同五模式晶格的数值模拟得到验证，在所考虑的构型上显示出良好的一致性。结果揭示了接近五模式极限与保持足够屈曲抗力之间的权衡，但也表明适当的连杆设计可以大幅提高屈曲极限，同时保留所需的五模式行为。
英文摘要
Pentamode lattices are architected materials characterized by an elastic response dominated by a single deformation mode. The low stiffness of the other deformation modes, however, may result in limited stability under compressive prestress, thereby limiting their mechanical performance. In this work, we develop a general analytical framework to determine the buckling limits of prestressed 2D and 3D isotropic pentamode lattices with generic link geometries. Two distinct instability mechanisms are considered: a global instability associated with the loss of stability of the effective medium, and a local instability associated with finite-wavelength modes at the scale of the lattice cell. Closed-form expressions for the corresponding critical pressures are derived, and the buckling limit is obtained as the lower of the two. The analytical predictions are validated through numerical simulations of different PM lattices, showing good agreement over the configurations considered. The results reveal a trade-off between approaching the pentamode limit and maintaining sufficient buckling resistance, but also show that appropriate link designs can substantially increase the buckling limit while retaining the desired pentamode behavior.
