Numerical simulation for delamination during drilling of CFRP/AL stacks

This paper is devoted to predicting the critical thrust force at delamination onset by finite element method in order to contribute the delamination-free drilling process of carbon-fiber-reinforced polymer/aluminum (CFRP/AL) stacks. First, taking the tapered drill point into account, a qualitative finite element analysis of push-out delamination is carried out to ascertain the location where the delamination first occurs. Mixed failure criteria and Camanho-Matthews stiffness' degradation criterion are applied to represent the damage initiation and evolution of CFRP. Second, three-dimensional finite element models are developed for predicting the critical thrust force of drilling CFRP/AL stacks at different stages by using traction-separation law to represent the interlaminar property. Finally, to validate the rationality of the finite element (FE) models, the results are compared with the previous theoretical and experimental results, and acceptable agreements have been obtained.