Crack Growth Monitoring of CFRP Composites Loaded in Different Environmental Conditions Using Acoustic Emission Method

New materials developed for aerospace structures continuously improve aircraft safety. New multifunctional nanostructured materials with exceptional properties must be tested and validated to exploit their full potential. Delamination is a typical damage mode for laminated composites. Therefore, reliable information regarding crack growth behaviour is needed for all operational environments of an aircraft operated at room temperature, as well as at cryogenic and elevated temperatures. In this paper, crack growth monitoring in a climatic chamber on double-cantilever beam (DCB) specimens using optical devices and acoustic emission (AE) techniques are described. A relationship between cumulative AE energy and crack growth in a plain-weave carbon fibre–reinforced epoxy is investigated under constant displacement rate loading at +80 °C and -55 °C. Test results are evaluated for specimens with nanofillers in the microstructure and for a reference material. The mechanical properties during delamination are represented by fracture toughness GIC, and they are also correlated with the AE data. The elevated test temperature caused a decreased rate of released AE energy. The results are affected by both temperature and material.