In classical fracture theory, the resistance to fracture is governed by the fracture toughness $G_c$, which is defined as the energy required to create new crack surfaces. To propagate a crack, the energy released to the crack tip (i.e. the energy release rate J) must overcome the fracture toughness $G_c$. Previous studies have demonstrated that surface stress can significantly modify the crack opening displacement and the stress field in soft solids and hence alter the energy release rate J, assuming small deformation. In this paper, we present a theoretical work on how surface stress affects fracture of soft solids under large deformation. We provide an expression of a modified J-integral for the energy release rate that accounts for surface stress. The expression is verified using large-deformation finite element analysis (FEA) with surface stress elements. Our results show that when the elastocapillary length, defined as the ratio of surface stress $\sigma$ to the Young’s modulus of the solid $E$, is comparable to the relevant material size, surface stress noticeably blunts the crack opening profile and reduces the energy release rate.

在经典断裂理论中，抗断裂性由断裂韧性决定 $G_C$，定义为产生新裂纹表面所需的能量。为了传播裂纹，释放到裂纹尖端的能量（即能量释放率J）必须克服断裂韧性$G_C$. 先前的研究表明，假设小变形，表面应力可以显着改变裂纹张开位移和软固体中的应力场，从而改变能量释放率J。在本文中，我们提出了关于表面应力如何影响大变形下软固体断裂的理论工作。我们提供了能量释放率的修正J积分表达式，该表达式解释了表面应力。该表达式使用具有表面应力元素的大变形有限元分析 (FEA) 进行验证。我们的结果表明，当弹性毛细管长度定义为表面应力的比率时$\sigma$ 固体的杨氏模量 $乙$, 与相关材料尺寸相当，表面应力显着削弱了裂纹开口轮廓并降低了能量释放率。