Interrogation of Lamb wave interaction with changing bonding condition in adhesive bonded joint

Abstract

Adhesive bonded joints, such as lap-shear joints or repair patches, are frequently adopted in structural applications. The quality degradation of adhesive will lead to disbond and the decrease of the interfacial strength. This study addresses the nondestructive evaluation of curing quality of adhesive layer using guided Lamb wave. When Lamb wave interacts with interface transition, both wave reflection and mode conversion complicate the interrogation of Lamb wave to characterize curing quality. A frequency domain finite element approach is adopted in this study to model the propagation of continuous sinusoidal Lamb waves into the bonded joint. Using this approach, the excitation of single Lamb wave mode at a single frequency is enabled, which excludes the mutual disturbance of multiple modes at a finite frequency band. Several regions at the dispersion curve of Lamb waves propagating in sandwich structure were investigated with the developed numerical model, showing different sensitivity to the curing quality characterized by the change of magnitude of Lamb wave. The obtained numerical results show a highly matched consistency with conventional time-domain numerical approach and experimental results, showing the potential of practical application of guide Lamb wave for assessment of curing quality in the bonded joint.