Fatigue crack growth (FCG) behavior of two symmetric cracks originating at different orientations from the outer periphery of a hole in an infinite plate under biaxial tension-tension loading is presented using two-dimensional boundary cracklet method. Symmetric precracks of known length and orientation are modelled as initial cracks, and biaxial traction is applied as a far-field loading. The rate of FCG is computed using Walker's equation, whereas the direction of propagation of crack tip is predicted using the minimum strain energy density criterion. The parametric study is performed with various orientations of initial precracks, biaxiality stress ratios (λ), and stress ratios (R) to show their effects on FCG behavior. Results suggest that for equiaxial loading, the crack propagation direction depends upon the position and initial angle of the crack. Cracks tend to grow perpendicular to that stress which is dominant of the two applied stresses when the biaxiality ratio is not unity.

中文翻译：

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使用边界裂纹法 (BCM) 进行双轴加载孔边缘裂纹的疲劳裂纹扩展分析

使用二维边界裂纹方法介绍了在双轴拉伸-拉伸载荷下，源自无限板中孔外周不同方向的两个对称裂纹的疲劳裂纹扩展 (FCG) 行为。已知长度和方向的对称预裂纹被建模为初始裂纹，双轴牵引作为远场载荷应用。FCG 的速率使用Walker 方程计算，而裂纹尖端的扩展方向使用最小应变能密度准则进行预测。参数研究是通过初始预裂纹、双轴应力比 (λ) 和应力比 (R) 的各种方向进行的，以显示它们对 FCG 行为的影响。结果表明，对于等轴加载，裂纹扩展方向取决于裂纹的位置和初始角度。当双轴度比不统一时，裂纹倾向于垂直于在两个施加的应力中占主导地位的应力增长。