Mechanical interface are widely employed in order to model fracture propagation phenomena along pre-assigned surfaces. Several aspects are involved in the description of the interface behavior. This paper is devoted to present an interface constitutive modeling which couples a cohesive behavior, based on the damage mechanics theory, with a frictional one, defined in a non-associative plasticity framework. By means of a specific interpretation of the damage variable, the formulation follows the transition of the initial sound interface material, up to the fully cracked condition. The macrocrack surface has initial frictional properties and is subjected to degradation phenomena. Namely, the smoothing and breaking of surface asperities causes a progressive reduction of dilatancy effects and of the frictional angle. These phenomena are modeled as uncoupled: dilatancy saturation is assumed to occur when relevant internal variable reach a limit value; frictional strength reduction occurs as effect of oligocyclic process, which takes place during the plastic sliding between the macrocrack surfaces. The constitutive framework presented in this paper belongs to the class of interface damage models. The frictional phenomena that develops in sliding deformation modes, in case of closure of the damaged interface, are modeled by non-associative plasticity laws. The model is developed in a fully compliance with thermodynamic principles. Finite element numerical tests are presented in order to show the main features of the proposed model.
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