Predicting post-impact compression strength of composite structures using the inverse method

Abstract

The application of carbon fiber-reinforced laminated composites is restricted due to the dramatic decrease of compression strength after impact, which can reach 70% at most. So far, there is no method of predicting the post-impact material performance that has been widely accepted by researchers, aircraft manufactures and aviation safety administrations. Recently, an inverse method was proposed for post-impact strength prediction by modeling impact damage as a soft inclusion with apparent material properties from experiment. This study aims to explore the inverse method in compression-after-impact (CAI) strength prediction of aircraft structures. First, a model and computer program to implement the validation of the inverse method was developed to determine the damage area properties. Then, experiments were conducted with the help of digital image correlation technology and the optimization program to measure the displacement field around damage zones and calculate the apparent material properties. Finally, a strategy of predicting post-impact compression strength of laminated composites was proposed based on the investigation of the compression properties of T700/M21.