Void Modelling and Virtual Testing of Prepreg Materials from 3D Image Capture

Abstract

Voids remain the most prolific manufacturing defect, and while the reduction in mechanical performance due to voids is well understood, the initial size, distribution, and evolution of voids during the manufacturing process is not well understood. In this study, the ply-ply interface of a laminate was replaced by a ply-glass interface and a high-resolution surface scanner was used to capture the surface topology of prepreg samples during the manufacturing processing. The size, shape, and depth of voids were captured and compared to a numerical method used to describe the evolution of the voids throughout processing. The model captures the void reduction trend during heating but some disparity remains in the final void size. The final experimentally measured void shape was used to predict the fracture toughness performance of the laminate. A finite element model was constructed from the surface images and the crack growth behavior was investigated using a multi-scale model of a double cantilever beam test. The fracture toughness and the stick-slip crack growth behavior of the samples were captured by the model. The continuing aim of this work is to advance both the experimental characterisation techniques and modelling capabilities in-order to deploy virtual performance testing from process simulation.