Damage progression and strength prediction of open-hole CFRP laminates containing ply gaps

Although automated fiber placement manufacturing can improve productivity, gaps and overlaps of plies occur due to the low position accuracy of the robot arm. This study develops the ply-by-ply shell layer model to investigate the mechanical effects of a gap on the damage progression and strength of composite laminates with a hole. The gaps and a hole are modeled independently of the mesh using the extended finite element method (XFEM) to reduce the preprocessing and computational costs using a simple square mesh. The opening of the resin rich area of the gap is represented by applying the cohesive zone model to the crack surface. The open hole tensile analysis was performed on a laminate with gaps. The predicted strength of specimen with gaps agrees well with the experiment and is slightly higher than that of specimen without gaps because the gap opening reduces the stress concentration at the hole.