Advanced modeling of mixed-mode adhesive materials and interfaces

Adhesive bonded joints have attracted the attention of many industries, such as marine and aerospace, as an interesting alternative to the traditional joining methods as riveting, bolting or welding. One of the most important damage modes of adhesive joints and interfaces is related to the non-linear and irreversible debonding process, which includes the formation and propagation of interface cracks, up to the complete detachment of the adherends. In this framework, the interfacial debonding problem is here handled through an innovative cohesive formulation, named as Enhanced Beam Theory (EBT), where the specimens are considered as an assemblage of two composite sublaminates, partly bonded together by an elastic interface. This last one is modeled with a continuous distribution of cohesive springs acting in the normal and/or tangential direction, depending on the mixed-mode condition. This generalizes the idea suggested recently in [1] for a single mode-I debonding, and extended in [2] to include mixed loading, geometry and mechanical conditions. The debonding onset and propagation is determined numerically along the weak interfaces subjected to mixed-mode conditions. The accuracy of the proposed formulation is verified against some analytical predictions and theoretical formulations available in literature [3], [4].