Gradient of Damage Enhancement for Cohesive Interface Laws

Gradient enhancements have become increasingly popular in the last decades for dealing with problems in mechanics suffering from spurious mesh sensitivity induced by strain softening. Many proposals exist in this sense and various techniques and formulations have been presented and successfully applied to study localization and fracture. Numerical results will be presented to show the superior performances of the damage enhanced model with reference to typical fracture propagation tests, where the gradient model is expected to provide meaningful answers quite independently from the mesh size. This improvement is neither marginal nor negligible mainly in view of identification of material parameters of the interface relationship via an inverse approach. Actually, even in the simplest deterministic case, the inverse procedure may require hundreds of forward analyses using a FE mesh that should be able to resolve the cohesive zone for a sufficiently wide range of material parameters