Semi-concurrent two-scale model for material failure based on the cohesive crack concept

S TORO; P. J. SANCHEZ; P.J. BLANCO; E. SOUZA NETO; A E. HUESPE; R FEIJÓO

Buenos Aires

Congreso; 1st Pan-American Congress on Computational Mechanics - PANACM 2015; 2015

IACM

This work presents a macro-micro semi-concurrent formulation develop ed to simulatefailure in materials with inne r heterogeneous structure. The distinctive feature of thepresent two-scale metho d is that the irreversible degradation pro cesses are mo deled byintro ducing the cohesive crack mechanical concept, at b oth s cales of analysis. The prop osed metho dology is based on the notion of Representative Volume Element (RVE). Itcan be considered as a generalization of a previous work of the authors in which failure, atthe micro-scale level, was considered through a smeared crack technique within a framework based on strain localization kinematics. As in that work, a well defined axiomaticvariational structure is adopted.The main novelty in this contribution is that failure patterns in the micro-scale caninclude multiple cohesive cracks, connected or disconnected, with dissimilar orientation,conforming a highly complex tortuous failure path. Tortuosity is a key aspect in themodelling of material degradation due to crack propagation, since the effective dissipatedenergy strongly depends on this parameter. The tortuosity effect is introduced in the multiscale formulation as a ?kinematical concept?, when the macro-kinematics is transferredinto the micro-scale. This is reached through the definition of a novel insertion operator.As a variational consequence, tortuosity affects the homogenized mechanical response forboth: (i) the overall stress state in the continuum part of the solid at macro-scale leveland (ii) the overall cohesive traction for points belonging to the macro-cohesive crack.In order to rigorously validate the proposed multiscale methodology, comparisonsagainst the so-called DNS (Direct Numerical Solution) approach are presented. Besides,some practical applications involving a concrete-like material, are also shown.