A Method to Extract Interface Stress Intensity Factors for Bimaterial Problems using Interlayers

A numerical method is presented here to determine stress intensity factors for interface cracks in plane, isotropic, elastic bimaterial fracture problems. The method relies on considering a companion problem wherein a very thin elastic interlayer with a crack, is artificially inserted between the two material regions of the original bimaterial problem. Modes I and II stress intensity factors are obtained for the companion problem using the modified virtual crack closure method. These stress intensity factors for the companion problem are then converted to the stress intensity factors for the original interface crack problem with the help of a universal relation. This universal relation between the stress intensity factors of the two problems is established by considering an asymptotic problem where the thickness of the interlayer is small compared with all other length scales. Two benchmark problems are considered to demonstrate the effectiveness of the interlayer approach for determining interface stress intensity factors.