The mixed mode crack problem in an inhomogeneous orthotropic medium

The mixed mode crack problem in plane elasticity for a graded and oriented material is considered. The material property grading is intentional, where as the property orientation or orthotropy is usually the consequence of mat erial processing. It is assumed that the crack is located in a plane perpen dicular to the direction of property grading and the principal axes of orth otropy are parallel and perpendicular to the crack. The four independent en gineering constants E-11, E-22, G(12), and nu(12) are replaced by a stiffne ss parameter, E = root E-11 E-22, a stiffness ratio, delta = (E-11/E-22)(1/ 4), a Poisson's ratio, nu = root nu(12) nu(21), and a shear parameter kappa (0) = (E/2G(12)) - nu. The corresponding mixed boundary value problem is re duced to a system of integral equations which is solved for various loading conditions and material parameters. The results presented consist of the s train energy release rate, the stress intensity factors and the crack openi ng displacements. It is found that generally the stress intensity factors i ncrease with increasing material inhomogeneity parameter and shear paramete r and with decreasing stiffness ratio.