复合型裂纹脆断主应变因子准则

提出了一种复合型裂纹脆断的主应变因子准则。该准则为：1）定义垂直于裂纹扩展径向平面上的主应变ε1及极径r的组合量√2πrε1为主应变因子ε1^-，裂纹将沿主应变因子取得最大值的径向扩展；2）垂直于裂纹扩展径向平面上的主应变因子的方向与原裂纹面法线方向的夹角为扩展裂纹面的扭转角，当主应变因子达到临界值时裂纹将失稳扩展。由此导出了裂纹的开裂方向和裂纹面扭转角有断裂方程。Ⅰ-Ⅲ复合型裂纹断裂试验表明：主应变因子准则与试验结果基本相符，利用其进行断裂评定较安全。

Principal strain factor criterion of mixed mode crack brittle fracture

Based on the test results, a new principal strain factorcriterion of mixed mode crack for brittle fracture is presented. The criterion consists of the following:1)Define a combination parameter of maximum strain ε1 on the plane of perpendicular to the radial direction of crack propagation and a polar vector to be principal strain factor , the direction of the maximum value of is one of the crack propagation ; 2)Let an angle between the direction of and the normal direction of the crack plane be the twist angle of crack plane, when reaches a critical value, the crack appears in unstable propagation, and the initial direction, twist angle of crack plane and the corresponding fracture equation can be deduced. Comparing the test results for the Ⅰ-Ⅲ mixed mode fracture of crack body with the theoretical predicting results provided in this paper, both have a good agreement, and the new principal strain factor criterion is of more rationality and safety for fracture evaluation of crack bodies.