Elastic neutral stability in compliant mechanisms is a remarkable appearance since it requires the energetic state of the structure to remain unchanged during a deformation mode. Several examples in literature require either plastic deformation or external constraints to be enforced to obtain a state of pre-stress and often require the use of anisotropic materials. This paper presents a new type of compliant shell structure featuring a neutrally stable deformation mode without requiring one of the aforementioned conditions. The shell structure is composed of two initially flat compliant facets that are connected via a curved crease. The structure can be reconfigured into a second zero-energy state via propagation of a transition region, without any apparent effort. Both the structure’s local width and local crease curvature can be tuned to reach neutral stability during transition. The modelled results are verified by several prototypes that match the modelled predictions qualitatively, as well as by measurement results that show quantitative agreement. The new type of structure introduced here features neutral stability without relying on the application of pre-stress during manufacturing or externally applied boundary conditions. Moreover, it shows potential for combining geometric simplicity with complex and highly tune-able behaviour.

柔性机构中的弹性中性稳定性是一个显着的外观，因为它要求结构的能量状态在变形模式期间保持不变。文献中的几个例子需要强制执行塑性变形或外部约束以获得预应力状态，并且通常需要使用各向异性材料。本文提出了一种新型柔顺壳结构，具有中性稳定变形模式，无需上述条件之一。外壳结构由两个最初平坦的柔顺面组成，这些面通过弯曲的折痕连接。该结构可以通过过渡区域的传播重新配置为第二个零能量状态，而无需任何明显的努力。可以调整结构的局部宽度和局部折痕曲率以在过渡期间达到中性稳定性。建模结果通过与建模预测定性匹配的几个原型以及显示定量一致性的测量结果进行验证。此处介绍的新型结构具有中性稳定性，不依赖于制造过程中施加的预应力或外部施加的边界条件。此外，它显示了将几何简单性与复杂且高度可调的行为相结合的潜力。此处介绍的新型结构具有中性稳定性，不依赖于制造过程中施加的预应力或外部施加的边界条件。此外，它显示了将几何简单性与复杂且高度可调的行为相结合的潜力。此处介绍的新型结构具有中性稳定性，不依赖于制造过程中施加的预应力或外部施加的边界条件。此外，它显示了将几何简单性与复杂且高度可调的行为相结合的潜力。