基于能量模型的三维穿透裂纹扩展研究

利用能量释放率与应力强度因子的关系,给出了裂纹尖端的有效能量释放率;裂纹稳定扩展时有效能量释放率恰好等于裂纹扩展阻力,利用裂纹尖端前沿各点的有效能量释放率相等关系,提出了一种基于能量模型的三维穿透裂纹扩展形貌计算方法,可以计算不同厚度试样的三维穿透裂纹扩展形貌,并通过不同厚度单侧裂纹板的有限元仿真计算和试验进行了验证.仿真与试验结果表明:利用基于能量模型的三维穿透裂纹扩展形貌计算方法可以确定三维结构的裂纹扩展形貌;随着单侧裂纹板厚度的增加,裂纹尖端"隧道效应"消失,裂纹扩展形貌转变为"马鞍"形;试样自由面处的裂纹扩展速率要小于中面处的裂纹扩展速率.

Study on three-dimensional through-thickness crack growth based on energy model

The effective energy release rate at crack tip was given by using the relation between energy release rate and stress strength factor. The effective energy release rate was equal to crack growth resistance at the crack growth, and the calculation method of three-dimensional through-thickness crack growth profile based on energy model was presented according to the equality relation of effective energy release rate for the crack tip front edge; the three-dimensional through-thickness crack growth profile of different thickness specimens could be calculated by using this method, and the finite element simulation and tests for single edge crack plates of different thickness were conducted to validate the calculation method. The simulation and test results show that the method of three-dimensional through-thickness crack growth profile based on energy model can be used to calculate crack growth profile of three-dimensional structures. The "crack tunneling" of crack tip disappeares when the thicknesses of single edge crack plates increase, and the crack growth profile turns into "saddle shape". The crack growth rate at specimen surface is smaller than crack growth rate at specimen middle face.