A multiscale formulation for cohesive fracture analysis

S. TORO; P.J. SÁNCHEZ; P.J. BLANCO; A.E. HUESPE; R.A. FEIJÓO

París

Conferencia; CFRAC-2015. International Conference on Computational Modelling of Fracture and Failure of Materials and Structures.; 2015

LMT-Cachan (ENS Cachan, CNRS, Université Paris Saclay). ECCOMAS

The contribution presents a multiscale formulation addressed to evaluate cohesive model developed for fracture problems. The multiscale methodology can be categorized as a semi-concurrent model, which uses a Representative Volume Element (RVE) to determine the cohesive forces at the macroscale.A variational multiscale formulation of the methodology has been previously presented by the authors ([1]). It has been shown there that the approach provides objective macroscale cohesive forces with respect to the microcell size, even after the onset of the strain localization process observed at the macroscopic scale.Subsequently, the formulation has been generalized and improved in three aspects: 1) cohesive surfaces are introduced at both scales of analysis; they are modeled with strong discontinuity kinematics. New equations describing the insertion of the macroscale strains, into the micro-scale and the posterior homogenization procedure are considered ([2]); 2) extention of the formulation to model elastoplastic large deformation problems; 3) the computational procedure and numerical implementation have been adapted to the improved formulation.The first and second points are emphasized here, while the third one is briefly summarized in this contribution.The methodology is numerically assessed through a number of simulations. Typically, quasi-brittle concrete fracture problem are modeled. The numerical simulation adequately captures the material degradation phenomenon at the mesostructural level, which induces the activation of cohesive surfaces at the structural scale.