A Cohesive interface formulation in large displacements

Mechanical interfaces are theoretical and computational tools able to properly reproduce the progressive decohesion along predefined surfaces. Scientific literature is rich of interface models, developed under very different conctitutive framework, but mostly developed in small displacements, whereas a few of them assess the problem in a geometrically nonlinear setting. In the present contribution interface formulation is rigorously developed in the large displacements regime. The relevant cohesive interface constitutive relations are defined in the local reference with normal and tangential axes to the middle surface in the current configuration. The interface is defined as a zero thickness layer with the traction vector acting between the two connected surfaces. Membrane forces are assumed negligible and separation displacement is assumed to remain small, at least up to full debonding.