A Cohesive-Frictional Interface Model with Frictional Properties Degradation

The paper is devoted to 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 layer, up to the fully cracked condition. The macrocrack surfaces have initial frictional properties and is subjected to degradation phenomena. Namely, the smoothing and breaking of surface asperities cause a progressive reduction of dilatancy effects and also 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 is assumed to occur as effect of an oligocyclic process, which takes place during the plastic sliding between the macrocrack surfaces. The constitutive model is developed in a fully compliance with thermodynamic principles. Some numerical branch tests are presented in order to show the main features of the proposed model. Finally, computational efficiency is verified by comparing the results of a FE applications with available experimental data