Boué Tamar Goldman, Cohen Gil, Fineberg Jay
The Racah Institute of Physics, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
Phys Rev Lett. 2015 Feb 6;114(5):054301. doi: 10.1103/PhysRevLett.114.054301. Epub 2015 Feb 2.
The origin of the microbranching instability is a long-standing unresolved issue in the fracture of brittle amorphous materials. We investigate the onset of this instability by measuring the real-time dynamics and symmetries of the strain fields produced by rapid tensile cracks in brittle gels. We find that once a simple tensile crack is subjected to shear perturbations, cracks undergo the microbranching instability above a finite velocity-dependent threshold. We further reveal a distinct relation between the microbranching and the oscillatory instabilities of rapid cracks.
微分支不稳定性的起源是脆性非晶材料断裂领域长期未解决的问题。我们通过测量脆性凝胶中快速拉伸裂纹产生的应变场的实时动力学和对称性来研究这种不稳定性的起始。我们发现，一旦简单的拉伸裂纹受到剪切扰动，裂纹在高于一个与速度相关的有限阈值时会经历微分支不稳定性。我们进一步揭示了快速裂纹的微分支不稳定性与振荡不稳定性之间的独特关系。
