We investigate the dissipative mechanisms exhibited by creased material sheets when subjected to mechanical loading, which comes in the form of plasticity and relaxation phenomena within the creases. After demonstrating that plasticity mostly affects the rest angle of the creases, we devise a mapping between this quantity and the macroscopic state of the system that allows us to track its reference configuration along an arbitrary loading path, resulting in a powerful monitoring and design tool for crease-based metamaterials. Furthermore, we show that complex relaxation phenomena, in particular memory effects, can give rise to a nonmonotonic response at the crease level, possibly relating to the similar behavior reported for crumpled sheets. We describe our observations through a classical double-logarithmic time evolution and obtain a constitutive behavior compatible with that of the underlying material. Thus the lever effect provided by the crease allows magnified access to the material's rheology.

中文翻译：

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折叠的弹性片的可塑性和老化

我们研究了折痕材料板在受到机械载荷时所表现出的耗散机制，这种耗散机理以折痕内的可塑性和松弛现象的形式出现。在证明可塑性主要影响折痕的静止角度后，我们设计了此数量与系统宏观状态之间的映射关系，使我们能够沿任意加载路径跟踪其参考配置，从而为功能强大的监测和设计工具基于折痕的超材料。此外，我们表明，复杂的松弛现象，特别是记忆效应，可以在折痕水平上引起非单调响应，这可能与折皱板的类似行为有关。我们通过经典的双对数时间演化来描述我们的观察结果，并获得与基础材料兼容的本构行为。因此，折痕提供的杠杆效应可以放大接触材料的流变性。