Crack curving in anisotropic elastic solids

The stress analysis for slightly curved cracks in an elastic anisotropic homogeneous solid is given by using a perturbation method combined with the approach of Muskhelishvili. For predicting the direction of the crack growth, higher order asymptotic stress fields at the tips of quasi-statically growing cracks under planar loading conditions are derived, and the maximum normal stress ratio criterion for orthotropic materials is analyzed. In terms of this criterion, the relationship of intensity factors at the crack tip is given and the crack curving is estimated. The calculations show that cracks in anisotropic materials may deviate from the straight path even under symmetric loading, and that the crack path stability as affected by the T stress exhibits different qualitative behavior, compared with crack growth in isotropic materials.