Health monitoring of bonded joints through electrical measurements

The aim of this research work is to explore the possibility of continuously monitoring the presence of damage in bonded joints through electrical measurements. Initially, an analytical model for estimating the crack length based on the electric resistance increase measured across the bond area is presented. The model is successfully validated through finite element analyses and experimental tests on single lap joints made of a conductive adhesive and aluminium or carbon/epoxy adherends. For the last case, the model is extended to account for damage scenarios where a residual conductivity is present across crack faces, due, for instance, to fibre bridging. Eventually, a procedure for predicting the crack length and the stiffness reduction in bonded joint based on electrical measurement is developed.