The cohesive zone is the elusive region in which material fracture takes place. Here, the putatively singular stresses at a crack’s tip are regularized. We present experiments, performed on PMMA, in which we visualize the cohesive zone of frictional ruptures as they propagate. Identical to shear cracks, these ruptures range from slow velocities to nearly the limiting speeds of cracks. We reveal that the cohesive zone is a dynamic quantity; its spatial form undergoes a sharp transition between distinct phases at a critical velocity. The structure of these phases provides an important window into material properties under the extreme conditions that occur during fracture.

中文翻译：

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快速断裂和摩擦中粘性区的动力学和性质

内聚区是发生材料断裂的难以捉摸的区域。在这里，裂纹尖端的假定奇异应力被规则化。我们介绍了在PMMA上进行的实验，在该实验中，我们可以看到摩擦破裂传播时的内聚区。与剪切裂纹相同，这些断裂的范围从缓慢的速度到几乎极限的裂纹速度。我们发现内聚区是一个动态量。它的空间形式以临界速度经历了不同相之间的急剧过渡。这些相的结构为断裂过程中出现的极端条件下的材料性能提供了重要的窗口。