METHODS FOR CALCULATING STRESS INTENSITY FACTORS FOR INTERFACIAL CRACKS BETWEEN 2 ORTHOTROPIC SOLIDS

Stress intensity factors for interfacial cracks between two dissimilar orthotropic materials were considered. Due to the oscillatory charact eristics of stresses and displacements near the crack tip, individual strain energy release rates no longer exist. Instead, the individual s train energy release rates corresponding to a finite crack extension w ere obtained in terms of the stress intensity factors and the assumed crack extension Delta a. The finite element methods in conjunction wit h the crack closure technique were used to calculate these finite exte nsion strain energy release rates from which accurate stress intensity factors were obtained. An alternative method based on crack surface d isplacement ratio was also discussed. Non-oscillatory (Delta a-indepen dent) Mode I and Mode II ''strain energy release rates'' were also pro posed to provide an alternate measure of fracture mode mixity or to be used as a fracture criterion for interfacial cracks. (C) 1998 Elsevie r Science Ltd. All rights reserved.