Predicting the residual strength for environmentally degraded adhesive lap joints

A cohesive zone model used to predict the residual strength of degraded adhesively bonded lap joints is presented in this paper. Interfacial failure of adhesive joints for a range of degradation was studied. A mixed mode interfacial rupture element was proposed with a traction-separation law. The two moisture dependent fracture parameters, fracture energy and tripping traction, were calibrated using a mixed mode flexure (MMF) test and finite element analyses. These parameters were used to model the thick adherend shear test (TAST) and single lap joint (SLJ) configurations without further modification. The ABAQUS FEA package was used to implement the coupled mechanical-diffusion analyses. The plasticity of the substrates was incorporated successfully and the predicted joint residual strengths agree well with the corresponding experimental data.