Elasto-plastic debonding strength of tensile steel/CFRP joints

In this paper the elasto-plastic debonding strength of tensile steel/CFRP joints (CFRP being the acronym for Carbon Fibre Reinforced Plastic) is investigated numerically, analytically and experimentally. A new formula to predict debonding strength of double shear lap joints with CFRP cover strips is proposed, based on fracture mechanics criteria, which takes into account the elasto-plastic steel behaviour. The results of this analytical formulation are validated by comparison with experimental and numerical results, where in the latter the debonding phenomenon between steel and CFRP strips has been simulated by a cohesive approach. Parametric analysis have been performed in order to investigate the influence of different design parameters such as steel and CFRP material parameters, fracture energy and adherents thicknesses on the debonding strength. Finally criteria to guarantee a ductile behaviour to the designed joints are proposed.