Ductile failure of heterogeneous materials : a cohesive-volumetric approach coupling analytical and numerical homogenization

Titre du congrès :ECCOMAS 2008 - 5th European Congress on Computational Methods in Applied Sciences and Engineering
Ville du congrès :Lido Venise
Date du congrès :30/06/2008

In the frame of the nuclear safety research programs of the French “Institut de Radioprotection et de Sûreté Nucléaire” (IRSN), a new approach was developed in order to predict the ductile fracture of heterogeneous materials during transient loadings. This approach is based on the so-called cohesivevolumetric finite element (CVFE) method in the periodic homogenization framework. The coupling
of this numerical approach to some analytical homogenization models allows to predict the behavior of heterogeneous materials from elasticity to ductile damage up to failure. The present paper shows the ability of this coupling in the case of two materials from the nuclear industry: (1) the uranium dioxide UO2 nuclear fuel, and (2) its cladding. The first example deals with the way to a posteriori enrich some homogenization estimates or bounds devoted to the ductile damage of porous materials in order to take into account the coalescence of cavities leading to failure. The second example illustrates a more coupled approach where the overall hardening behavior of a composite material (as elastoplasticity) is incorporated into the bulk behavior and the overall softening behavior (as damage and fracture) is incorporated into some cohesive zone models.