THE QUASI-INVARIANT IN THE THEORY OF INTERFACE CRACKS

An interface crack model which takes the frictionless contact surfaces near the crack tip is investigated in an analytical manner. An exact solution for the bimaterial plane in the removal traction-shear field is obtained for arbitrary contact interval length. The true length which provides a physically correct state of the crack is found. The new combination of stress intensity factors and its almost negligible independence on contact interval length are shown. An effective application of the new quasi-invariant to the numerical investigation of the interface problem is proposed.