A study of delamination on graphite/epoxy composites in abrasive waterjet machining

Delamination is a major component defect when machining composites or layered materials. This study aims to explore the mechanism of delamination in graphite/epoxy composites under abrasive waterjet (AWJ) machining. It is found that crack tips are generated by the shock wave impact of the waterjet at the initial cutting stage, while delamination is a result of water penetration into the crack tips that promotes water-wedging and abrasive embedment. Based on an energy conservation approach, a semi-analytical model is developed to predict the maximum delamination length generated by an AWJ. The model prediction is found in good agreement with the experimental data and can be used as a practical guide for process planning to minimise or eliminate the delamination defects on the components in AWJ machining of graphite/epoxy composites.