玻璃在 cavitation 失效过程中的大伸长超弹性
Large dilatational hyperelasticity of glasses en route to cavitation failure
AI总结：
研究揭示了玻璃在接近失效时，大和小应力三轴度下的弹性塑性变形差异，发现大三轴度下玻璃表现出强超弹性响应，而小三轴度下则伴随微空腔形成，揭示了玻璃失效的拓扑转变过程。
摘要：
材料在各种加载条件下发生弹塑性变形并失效，通常通过应力三轴度量化，即体积应力与剪切应力的比值。我们显示，玻璃接近失效时的弹塑性变形在大和小应力三轴度水平下存在显著差异。具体而言，在前者极限下，玻璃表现出强超弹性（非线性弹性）响应，具有极小的塑性，与玻璃转变过程中的淬火速率基本无关。然而，玻璃中的无序结构导致显著的弹性（可逆）非仿射变形，并伴随微空腔的形成。后者的小部分是不可逆的，即在卸载前存活，可能作为失效的起始点，以大尺度空化形式出现，伴随拓扑转变并形成内部自由表面，使玻璃失去大量承载能力。这些结果与应力三轴度趋近于零时的玻璃行为形成对比，并在不同玻璃形成体中表现出普遍性。最后，讨论了我们的发现对理解玻璃在真实应力条件下的变形和失效的启示。
英文摘要：
Materials deform elasto-plastically and fail under various loading conditions, typically quantified by the stress triaxiality, which is the ratio between the dilatational (hydrostatic) stress and the deviatoric (shear-like) one. We show that the elasto-plastic deformation of glasses approaching failure qualitatively differ for large and small stress triaxiality levels. Specifically, in the former limit, glasses reveal a strong hyperelastic (nonlinear elastic) response with minute plasticity, largely independently of the quenching rate across the glass transition. Yet, glassy disorder gives rise to significant elastic (reversible) nonaffine deformation, accompanied by the formation of micro-cavities. A small fraction of the latter is irreversible, i.e., survives unloading prior to the onset of failure, and may serve as nucleation sites for failure in the form of large-scale cavitation, involving a topological transition accompanied by the formation of an internal free surface, upon which the glass loses a significant fraction of its load-bearing capacity. These results are contrasted with glass behavior in the limit of vanishing stress triaxiality and their universality across different glass formers is demonstrated. Finally, the implications of our findings for understanding glass deformation and failure under realistic stress conditions are discussed.
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