Residual stiffness of bonded joints for fibre-reinforced polymer profiles

In this paper we present an experimental study on the behaviour of samples concerning double lap joints made of glass fibre-reinforced polymer composite (GFRP). According to a multistep displacement/force control procedure, a data driven approach is performed with the aim of investigating the behaviuor of adhesive joints between GFRP profiles at service conditions focusing on the non-linearity of the interfacial damage as the number of cycles increases. The present analysis has been performed regardless of the consideration of material/geometric non-linearities, which affect, instead, the failure load or the buckling limit. The final results provide a database for sketching a predictive rule to be used for a direct evaluation of the loss of stiffness of the joint.