This work presents a numerical investigation into the dynamic crack penetration vs. deflection at a material interface, for materials exhibiting strain rate dependent damage evolution. The rate dependence of damage manifests as an increased strength and fracture energy (or toughness) at higher strain rates. For this purpose, a strain rate dependent continuum damage mechanics (CDM) based model is considered, which scales the material point softening damage law as a function of the strain rate. The investigations consider two materials, viz. the bulk and the interface, both modeled via the foregoing rate dependent damage model. Attention is focused on a mode I dynamic bulk crack impinging the interface at right angles, for the case where the interface is more strain rate sensitive than the bulk. The model is calibrated and validated with experimental data, and found to predict well the penetration/deflection behavior of a dynamic crack at an interface. Despite this, the predicted crack trajectory approaching the specimen boundary appears to be affected in some cases. The model is then used to conduct a sensitivity analysis for a wide range of bulk and interface properties (moduli, strengths, and fracture energy). The analyses reveal that dynamic crack impingement at the interface is accompanied by sharp changes in the local strain rates, thus altering the local bulk and interface strengths and toughnesses. So, a weak interface can become stronger and tougher than the bulk, locally and instantaneously, if it exhibits a higher strain rate sensitivity than the bulk. This implies that when damage evolution is rate dependent, there is an increased tendency for crack penetration. Due to the local and instantaneous rate dependence of strength and toughness, the previously established criteria in terms of the quasistatic property ratios are shown to be inapplicable. Alternatively, modeling is deemed inevitable for which the main source of uncertainty comes from the boundary conditions, which are shown to significantly affect the predicted cracking behavior.

这项工作对材料界面处的动态裂纹穿透与偏转进行了数值研究，适用于表现出应变率相关损伤演化的材料。损伤的速率依赖性表现为在较高应变速率下强度和断裂能（或韧性）增加。为此，考虑了基于应变率相关连续体损伤力学 (CDM) 的模型，该模型将材料点软化损伤规律缩放为应变率的函数。调查考虑了两种材料，即。体积和界面，均通过上述速率相关损伤模型建模。注意力集中在模式 I 动态体裂纹以直角冲击界面，对于界面比体对应变率更敏感的情况。该模型通过实验数据进行了校准和验证，发现可以很好地预测界面处动态裂纹的穿透/偏转行为。尽管如此，在某些情况下，接近试样边界的预测裂纹轨迹似乎受到影响。然后使用该模型对范围广泛的体积和界面属性（模量、强度和断裂能）进行敏感性分析。分析表明，界面处的动态裂纹冲击伴随着局部应变率的急剧变化，从而改变了局部体积和界面强度和韧性。因此，如果弱界面表现出比本体更高的应变率敏感性，它可以在局部和瞬时变得比本体更强韧。这意味着当损伤演化取决于速率时，裂纹渗透的趋势增加。由于强度和韧性的局部和瞬时速率依赖性，先前建立的准静态性能比标准被证明是不适用的。或者，建模被认为是不可避免的，其不确定性的主要来源来自边界条件，这些边界条件被证明会显着影响预测的开裂行为。