Kinked crack in anisotropic bodies

Solutions are presented for a crack kinking out of the crack plane in a generally anisotropic elastic body under two-dimensional deformation. Based on Stroh formalism, a system of singular integral equations governing the kinking crack with small kink length is given in a simple, straightforward form. The explicit expressions of the stress intensity factors, T-stresses, and energy release rates at the kinked crack tip are presented in terms of some nondimensional coefficients together with the stress intensity factors, T-stresses, and the coefficients of the third term acting on the main crack tip prior to crack kinking. The nondimensional coefficients depend on kink angle and material constants, but not on kink length. The energy release rate ratio which may characterize the competition along different crack growth directions is provided. The role of T-stresses and the third-term applied at the main crack field are determined which can be significant in the kinking and the stability of the kinked crack. Based on the energy release rate fracture criterion, the stability condition of the kinked crack is derived. The influences of anisotropy and loading mixity on the implications of crack kinking behavior is also given. The results for monoclinic materials with symmetry plane at x₃ = 0 are derived from general results. Numerical results for the stress intensity factors, T-stresses at the kinked acrack tip and the energy release rate ratio for some special cases are provided. The dimensionless coefficients for crack kinking of orthotropic materials at the right angle to the main crack plane are tabulated.