Crack growth on elastic-plastic bimaterial interfaces

A finite element calculation based on finite strain theory is carried out to simulate crack growth on bimaterial interfaces under the assumption of small scale yielding and plane strain. The modified Gurson's constitutive equation and the element vanish technique are used to model the final formation of an open crack. The crack growths in a homogeneous material and in bimaterials are compared. It is found from the calculation that the critical macroscopic fracture toughness for crack growth, JIC, is much lower in bimaterials than in homogeneous material. For bimaterial cases, the JIC of a crack between two elastic-plastic materials which have identical elastic properties with different yield strength is lower than that of a crack between an elastic-plastic material and a rigid substrate.