Validation is carried out of the previously proposed implicit criterion for choosing the direction of a fracture propagation under the complex loading characterized by the presence of all three modes of the stress intensity factors K_I, K_II, and K_III. The criterion is based on the principle of local symmetry according to which the fracture propagates in the direction providing the zero values of the factors of both mixed modes K_II and K_III. Since in the general case the two conditions cannot be satisfied simultaneously, the criterion is formulated as a minimization problem for a functional that contains the sum of the values of the mixed modes integrated along the entire front of the fracture. The formulation of the criterion includes some parameter that describes the effect of each of the mixed modes; the value of this parameter should be chosen by using the experimental data. Based on two fracture propagation experiments with complex mixed loading, validation of the criterion is carried out and some estimates are given for the interval of the best value of the weight parameter.

中文翻译：

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混合载荷作用下裂纹扩展的整体隐式判据

对先前提出的隐性准则进行了验证，该准则用于选择以应力强度因子K _I，K _II和K _III的所有三种模式都存在为特征的复杂载荷下的裂缝传播方向。该准则基于局部对称性原理，根据该原理，裂缝沿提供混合模式K _II和K _III的因子的零值的方向传播。。由于在一般情况下不能同时满足两个条件，因此将标准公式化为一个函数的最小化问题，该函数包含沿裂缝的整个前端积分的混合模式值的总和。准则的制定包括描述每个混合模式效果的一些参数。该参数的值应通过实验数据来选择。基于两个复杂混合荷载的裂缝扩展实验，对该准则进行了验证，并对权重参数最佳值的区间给出了一些估计。