Direct prediction of mechanical energy released by damaged single lap joints using acoustic emission signals combined with finite element analysis

Adhesively bonded single lap joints are common structures in lightweight design. Despite several advantages, damage initiation and propagation are critical and can be evaluated with structural health monitoring methods. This research combines analytical models and finite element analyses (FEAs) with acoustic emission (AE) measurements to predict the released mechanical energy (RME) during damage evolution. Two geometries, either with both adherends of constant thickness or with one constant and one tapered adherend, are evaluated. One adherend consists of carbon fibre reinforced polymer, the other one of additively manufactured titanium. The work input during quasi-static loading for the overlap region is calculated based on the longitudinal load and displacement, and based on the longitudinal, lateral, and bending components. For the calculation of the RME, pristine and damaged load–displacement curves are compared. The pristine trends are represented by the extrapolation of an experiment, or an analytical model, or a FEA without failure model. Whereas, the damaged trends are either given by the experimental measurements or a FEA with included failure model. Furthermore, the RME can also be gathered directly from the FEA with failure model. By linking the AE energy with the RME, the RME of a validation sample can be predicted.