FINITE-ELEMENT ESTIMATES OF STRAIN-ENERGY RELEASE RATE COMPONENTS AT THE TIP OF AN INTERFACE CRACK UNDER MODE-I LOADING

The strain energy release rate components G(1) and G(II) in mode I and mode II at the tip of an interface crack in a bimaterial plate under tension in a direction normal to the interface were evaluated using finite element analysis and Modified Crack Closure integral (MCCI) technique. Three models, namely the bare interface model, the resin layer model and the subinterface crack model were studied with two different material combinations with progressively decreasing crack tip element size Delta a which is also the virtual crack extension considered in the MCCI evaluation. The finite element results for all the models show increasing mode II dominance as Delta a --> 0. Interpretation of these results is meaningful if the virtual crack extension Delta a is identified as crack growth step size.