New solution coefficients for crack kinking at orthotropic bimaterial interfaces

Studying and controlling crack kinking is important for many problems, for instance to analyse crack propagation and in the design of damage mitigation concepts. The model formulated by He and Hutchinson (1989), later extended by He et al. (1991), defines the stress intensity factors at the tip of the kinked crack as a linear combination of the complex stress intensity factor of the interface crack and the non-singular crack tip in-plane stress through three complex coefficients. The coefficients depend on the elastic properties of the materials and the kink angle, and have been derived and tabulated for some material combinations. Composite materials used nowadays in the naval and aeronautical sectors are not included. In this work a semi-analytical approach is adopted to derive new coefficients, not available in the literature, for isotropic interfaces with extreme elastic constants mismatches and for modern orthotropic interfaces commonly used in the aeronautical and naval sectors. The approach uses finite element analyses, and algebraic manipulation of the numerical results. The methodology to compute the coefficients is presented and verified using reference values available in literature, and the new computed coefficients are tabulated in the supplementary material. The interpolation of the tabulated coefficients enables the calculation of solutions suitable for interfaces not considered in this manuscript.