A Cohesive-frictional interface model subjected to mixed complex loading paths

The paper presents a cohesive-frictional interface model based on surface damage mechanics. The proposed model is developed under the assumption that the fracture energies in mode I and in mode II are different values, as shown by several experimental evidences. At difference with the most spread available interface models, only one isotropic interface internalvariable is adopted for the constitutive model. The interface constitutive model is developed in a Thermodynamic consistent framework with an Helmholtz free energy potential and the fulfillment of the thermodynamic principles is obtained enforcing the Clausius-Duhem inequality. The damage/friction activation functions and dissipative flow potentials are defined together with nonassociative flow rules and loading/unloading conditions. The latter loading/unloading conditions emerge directly from the nature of the proposed approach, which is framed in the mechanics dissipative process with internal variables, and then does not require any special ad-hoc unloading rule. Finally, some numerical examples of interface subjected to complex mixed loading/unloading/reloading paths are analyzed