Analytical expressions for J_k-integrals of orthotropic/isotropic interface cracks

This paper presents new analytical expressions for J_k integrals in terms of the stress intensity factors (SIF) of an in-plane traction free interface crack in an orthotropic/isotropic bimaterial. Using the sextic formalism of Stroh and Muskhelishvili formulation, a general solution for the stress and displacement fields near the interface crack of this bimaterial are derived. This paper also presents an analytical expression for the SIFs of a finite interface crack in an infinite orthotropic/isotropic bimaterial subject to in-plane remote stresses. For validation of the presented theory, the analytical J_k integrals, crack opening displacements and stresses along the interface of an infinite orthotropic/ aluminum plate with a finite interface crack subject to tension are compared with the corresponding numerical results obtained using the boundary element method. For the orthotropic material, different fibre reinforced polymers are considered. The results show that a metal/fibre composite can be tailored to crack growth resistance. This study provides explicit analytical expressions for fracture parameters of cracks between isotropic and orthotropic materials which are not currently available in the SIF handbooks.