A local comparison of the virtual crack closure technique and a cohesive zone model in calculating the strain energy release rate for large and curved delaminations

The two most common techniques to predict delamination in composites are the Cohesive Zone Model (CZM) and the Virtual Crack Closure Technique (VCCT). These were compared in previous works by only analysing the load–displacement response of different specimens. As shown in this work, this is not sufficient since local computations of the Strain Energy Release Rate (SERR) can be significantly different if large and curved delaminations are involved. This work presents an in-depth comparative strategy based on a local SERR comparison between VCCT and CZM. This strategy was used to compare the two techniques for a non-standard specimen featuring large and curved delamination fronts loaded under mode I and shear modes. A total of 75 SERR distributions show how significant differences may arise between the two techniques. Compared to the current literature, we were able to highlight the importance of considering the SERR instead of global descriptors in comparing the two techniques. This work thus highlights strengths and criticalities of the VCCT and CZM, suggests possible sources of inaccuracies and provides useful guidelines for their better use.