Analysis of an elliptical crack parallel to graded interfacial zone of bonded bi-materials

This paper analyzes an elliptical crack parallel to the functionally graded interfacial zone between two fully bonded solids. The functionally graded interfacial zone is treated as a nonhomogeneous solid layer with its elastic modulus varying in the thickness direction. A generalized Kelvin solution based boundary element method is employed for the calculation of the stress intensity factors associated with the three-dimensional crack problem. The elliptical crack surface is subject to either uniform normal traction or uniform shear traction. The stress intensity factors are examined by taking into account the effects of the nonhomogeneity parameter and thickness of the functionally graded interfacial zone, as well as the crack distance to the zone. The numerical results are in very good agreement with the existing solutions under degenerated conditions. These stress intensity factor values can be further used to predict the crack growth in the functionally graded materials.