Acoustic Emission Based Monitoring of Fatigue Damage in CFRP-CFRP Adhesive Bonded Joints

Adhesive bonded joints are more and more applied in modern structures. However, manufacturing defects and particularly harsh operative conditions might cause local de-bonding and catastrophic failures. Structural Health Monitoring and Non-destructive Testing procedures are, then, needed for evaluating the in-service structural integrity of adhesive bonded joints. In this research, an adhesive bonded single lap joint, whose both adherends are manufactured using a carbon fiber reinforced polymer composite, is subjected to constant amplitude fatigue loading. During such a test, the integrity and damage condition of the joint is continuously monitored by acoustic emission, while the test itself is periodically interrupted in order to apply micro-computed tomography to the specimen, with the aim to investigate the real features of the developing fatigue damage. Results show that monitoring by acoustic emission, after suitable elaboration and filtering my means of pattern recognition algorithms, allows identifying and characterizing effectively the development of fatigue damage in adhesive bonded joints.