Inline quantification and localization of transverse matrix cracking in cross-ply CFRP during quasi-static tensile testing by a joint event-based evaluation of acoustic emission and passive IR thermography

Abstract Understanding the complex damage characteristics of fiber reinforced plastics under mechanical loading is essential for lightweight design. In this study, acoustic emission (AE)1 analysis and passive IR thermography (pIRT) are coherently combined for the quantitative characterization and localization of damage progression in cross-ply carbon fiber reinforced plastics under quasi-static tensile loading. A new evaluation methodology is presented that utilizes acoustic events as trigger for pIRT analysis. Rigourosly transferring the event-based evaluation scheme from AE to pIRT analysis allowed for the first time to extract and compare characteristic features from both: thermal and corresponding acoustic events and to correlate them to the underlying damaging event. This way, the thermal and acoustic footprint of transverse matrix cracking (TMC) in the outer 90° layers was successfully identified and used for the determination of TMC onset and density throughout the test. This highlights the potential for the inline characterization of damage progression with this new approach.