Abstract In an earlier work (Tang et al., 2020), we derived evolution equations governing dynamic void growth in amorphous materials with a number of idealizing assumptions. Here, we extend and further generalize the constitutive theory to better account for general stress states, strain-softening, stable and unstable void growth modes, as well as viscous and micro-inertial retarding effects on void growth rates. The enhanced theory is implemented into a commercial finite element software package via a user-defined material subroutine to understand transitions in fracture morphologies. In particular, metallic glasses exhibit a dimple type fracture mode at low impact velocities, which transitions to a cup-cone type fracture mode at higher impact velocities. Our theory reveals that two competing processes drive this transition: (i) strain-softening behavior that is inherent to many amorphous materials and (ii) a so-called stress plateau effect that arises due to bursts of stable and unstable void growth. Our simulation results also suggest that strain-softening during the dynamic compression phase, which precedes subsequent tensile failure, is essential to the formation of cup-cone fracture morphology.

中文翻译：

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一种基于微力学的框架，用于预测冲击金属玻璃中凹坑和杯锥断裂模式之间的转变

摘要 在早期的工作中 (Tang et al., 2020)，我们推导出了控制非晶材料中动态空隙生长的演化方程，其中包含一些理想化假设。在这里，我们扩展并进一步推广本构理论，以更好地解释一般应力状态、应变软化、稳定和不稳定的空隙生长模式，以及粘性和微惯性对空隙生长速率的阻碍作用。增强的理论通过用户定义的材料子程序实现到商业有限元软件包中，以了解断裂形态的转变。特别是，金属玻璃在低冲击速度下表现出凹坑型断裂模式，在较高冲击速度下转变为杯锥型断裂模式。我们的理论表明，有两个相互竞争的过程推动了这种转变：(i) 许多非晶材料固有的应变软化行为和 (ii) 由于稳定和不稳定的空隙增长爆发而产生的所谓的应力平台效应。我们的模拟结果还表明，在随后的拉伸破坏之前的动态压缩阶段的应变软化对于杯锥断裂形态的形成至关重要。