Baumberger T, Caroli C, Martina D, Ronsin O
INSP, UPMC Université Paris 06, CNRS UMR 7588, 140 rue de Lourmel, 75015 Paris, France.
Phys Rev Lett. 2008 May 2;100(17):178303. doi: 10.1103/PhysRevLett.100.178303. Epub 2008 May 1.
The full 2D analysis of roughness profiles of fracture surfaces resulting from quasistatic crack propagation in gelatin gels reveals an original behavior characterized by (i) strong anisotropy with maximum roughness at V-independent symmetry-preserving angles and (ii) a subcritical instability leading, below a critical velocity, to a cross-hatched regime due to straight macrosteps drifting at the same magic angles and nucleated on crack-pinning network inhomogeneities. Step height values are determined by the width of the strain-hardened zone, governed by the elastic crack blunting characteristic of soft solids with breaking stresses much larger than low strain moduli.
对明胶凝胶中准静态裂纹扩展产生的断裂表面粗糙度轮廓进行的完整二维分析揭示了一种原始行为，其特征为：(i) 具有很强的各向异性，在与速度无关的保对称角度处粗糙度最大；(ii) 一种亚临界不稳定性，在临界速度以下，由于直的宏观台阶在相同的神奇角度漂移并在裂纹钉扎网络不均匀性处形核，导致出现交叉阴影区域。台阶高度值由应变硬化区的宽度决定，该宽度由软固体的弹性裂纹钝化特性控制，其断裂应力远大于低应变模量。
