Confirming the continuum theory of dynamic brittle fracture for fast cracks
Confirming the continuum theory of dynamic brittle fracture for fast cracks
复制标题
DOI：
10.1038/16891
复制
发表时间：
1999
期刊：
影响因子：
64.8
通讯作者：
E. Sharon;J. Fineberg
中科院分区：
文献类型：
--
作者：
E. Sharon;J. Fineberg
裂纹扩展是材料失效的基本机制。脆性非晶材料动态断裂实验的结果与极低速度下单裂纹运动的理论预测一致。但在更高的速度下，我们观察到了许多与理论的明显差异。特别是，非晶材料中达到的最大裂纹速度远慢于预测的渐近值 vR。超过临界速度 vc≈ 0.4vR，就会观察到内在的不稳定性，其中重复的、受挫的微分支事件会形成多裂纹状态。这些会导致速度振荡并可以解释明显的异常现象。在这里，我们报告了脆性非晶材料动态断裂的测量结果，从传播的初始阶段到 tovc，这些测量结果与理论单裂纹运动方程定量一致。 Beyondvc，由于多裂纹系综的出现，协议破裂了。但在这种情况下，微分支过程可以瞬间产生单裂纹状态，该状态立即达到其预测的单裂纹速度，速度高达 0.9vR。因此，我们的结果证实了弹性脆性断裂单裂纹连续体理论的有效性，即使在裂纹形态复杂的动态状态下也是如此。
Crack propagation is the basic mechanism of materials failure. Experiments on dynamic fracture in brittle amorphous materials have produced results that agree with theoretical predictions for single-crack motion at very low velocities. But numerous apparent discrepancies with theory have been observed,,at higher velocities. In particular, the maximum crack velocities attained in amorphous materials are far slower than the predicted asymptotic value,vR. Beyond a critical velocity,vc≈ 0.4vR, an intrinsic instability has been observed in which a multiple-crack state is formed by repetitive, frustrated micro-branching events. These cause velocity oscillations and may explain the apparent anomaly. Here we report measurements of dynamic fracture in a brittle, amorphous material that are in quantitative agreement with the theoretical single-crack equation of motion, from the initial stages of propagation up tovc. Beyondvc, agreement breaks down owing to the appearance of the multiple-crack ensemble. But in this regime, the micro-branching process can momentarily produce a single-crack state which instantaneously attains its predicted single-crack velocity, for velocities up to 0.9vR. Our results therefore confirm the validity of the single-crack continuum theory of elastic brittle fracture even in the dynamical regime where the crack morphology is complex.