Baumberger T, Ronsin O
INSP, UPMC Univ Paris, CNRS UMR, Paris, France.
Eur Phys J E Soft Matter. 2010 Jan;31(1):51-8. doi: 10.1140/epje/i2010-10546-x. Epub 2010 Jan 20.
Experiments on quasistatic crack propagation in gelatin hydrogels reveal a new branching instability triggered by wetting the tip opening with a drop of aqueous solvent less viscous than the bulk one. We show that the emergence of unstable branches results from a balance between the rate of secondary crack growth and the rate of advection away from a non-linear elastic region of size G/E , where G is the fracture energy and E the small strain Young modulus. We build a minimal, predictive model that combines mechanical characteristics of this mesoscopic region and physical features of the process zone. It accounts for the details of the stability diagram and lends support to the idea that non-linear elasticity plays a critical role in crack front instabilities.
明胶水凝胶中准静态裂纹扩展实验揭示了一种新的分支不稳定性，该不稳定性是由一滴比主体溶剂粘性更小的水性溶剂润湿裂纹尖端开口引发的。我们表明，不稳定分支的出现源于二次裂纹扩展速率与从尺寸为G/E的非线性弹性区域平流离开的速率之间的平衡，其中G是断裂能，E是小应变杨氏模量。我们构建了一个最小化的预测模型，该模型结合了这个细观区域的力学特性和过程区的物理特征。它解释了稳定性图的细节，并支持了非线性弹性在裂纹前沿不稳定性中起关键作用这一观点。
