The effects of voids on the flexural properties and failure mechanisms of carbon/epoxy composites

Abstract

Although the effect of voids on the mechanical properties of composite failures has been well researched, their effect on the failure mechanisms has not been well characterised. This study investigated the effect of the void content on the flexural strength of carbon/epoxy composites and to explain in terms of the failure mechanisms. The results showed that a 2% increase in void content reduced the flexural strength by 12.7%. Using optical microscopy, X-ray tomography and acoustic emission it was found that voids had no effect upon compression crack initiation but were found to influence the initiation and propagation of delaminations. A combination of in-situ acoustic emission and X-ray tomography proved to be a powerful tool in providing evidence of the failure mechanisms.