Residual Strength Prediction of Impacted CFRP Laminates

Abstract

A model for the prediction of residual tensile strength of impacted CFRP laminates is presented and discussed. The damage zone is considered, from the residual strength standpoint, as an equivalent implanted hole, and strength degradation is calculated using a linear elastic fracture mechanics approach previously proposed. The results of experimental tests, carried out at low velocity on AS/3501 (0/±45) 2s laminates, show a good correlation with theoretical predictions; moreover, data available in the literature seem to indicate the effectiveness of the proposed formula in foreseeing the com pressive strength degradation due to impact. The physical meaning of the parameters appearing in the model, together with the data here presented, suggests a method to obtain the residual strength curve as a func tion of impact energy by a minimum number of experimental tests. This method is ex pected to be valid for rate-insensitive materials such as carbon fiber reinforced laminates.