Acoustic emission-based monitoring of fatigue damage in CFRP-CFRP adhesively bonded joints

Abstract

Adhesively bonded joints are being increasingly applied in modern structures. However, manufacturing defects and particularly harsh operative conditions may cause local debonding and catastrophic failures. Structural health monitoring (SHM) and non-destructive testing (NDT) procedures are then needed to evaluate the in-service structural integrity of adhesively bonded joints. In this research, an adhesively bonded single-lap joint, both adherends of which are manufactured using a carbon fibre-reinforced polymer (CFRP) composite, is subjected to constant amplitude fatigue loading. During such a test, the integrity and damage condition of the joint is continuously monitored using acoustic emission (AE), while the test itself is periodically interrupted in order to apply micro-computed tomography (μCT) to the specimen, with the aim of investigating the real features of the developing fatigue damage. The results show that, after suitable elaboration and filtering by means of pattern recognition algorithms, acoustic emission-based monitoring allows for effective identification and characterisation of the development of fatigue damage in adhesively bonded joints.

Debonding quantification in adhesive bonded joints by the inverse finite element method

“…Latest research has investigated the mechanical behavior of polymer optical fibers embedded in adhesive bulk specimens subjected to tensile loading [28]; distributed fiber optic measurements were used to monitor adhesive bonded joints comparing the results with DIC in [29] and with x-ray microtomography in [30]. Acoustic emissions have also been demonstrated suitable for online monitoring in a laboratory environment [31]. In [32], the authors proposed the shifts in the strain peak measured by distributed fiber optic sensors as features to quantitatively monitor crack growth in double cantilever beam specimens.…”