Livne Ariel, Ben-David Oded, Fineberg Jay
The Racah Institute of Physics, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
Phys Rev Lett. 2007 Mar 23;98(12):124301. doi: 10.1103/PhysRevLett.98.124301. Epub 2007 Mar 21.
Experiments of pure tensile fracture in thin brittle gels reveal a new dynamic oscillatory instability whose onset occurs at a critical velocity, VC=0.87CS, where CS is the shear wave speed. Until VC, crack dynamics are well described by linear elastic fracture mechanics (LEFM). These extreme speeds are obtained by suppression of the microbranching instability, which occurs when sample thicknesses are made comparable to the minimum microbranch width. The wavelength of these sinusoidal oscillations is independent of the sample dimensions, thereby suggesting that these macroscopic effects are due to an intrinsic microscopic scale that is unrelated to LEFM.
薄脆凝胶中的纯拉伸断裂实验揭示了一种新的动态振荡不稳定性，其起始发生在临界速度(VC = 0.87CS)处，其中(CS)是剪切波速度。在达到(VC)之前，裂纹动力学可以用线弹性断裂力学（LEFM）很好地描述。这些极端速度是通过抑制微分支不稳定性获得的，当样品厚度与最小微分支宽度相当时会出现这种不稳定性。这些正弦振荡的波长与样品尺寸无关，因此表明这些宏观效应是由与LEFM无关的固有微观尺度引起的。
