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SUMMARY:Numerical Analysis : A new multi-scale variational formulation to 
 model material failure
DTSTART:20120220T141500
DTEND:20120220T150000
DTSTAMP:20260407T025714Z
UID:8ce74deab31338d02adc519772e7cf71cdcb5f7ef493bc4d2cfb4d64
CATEGORIES:Conferences - Seminars
DESCRIPTION:Dr. Pablo Javier BLANCO (Laboratorio Nacional de Computaçao C
 ientifica\, Rio de Janeiro\, Brasil\nAbstract:\nThis contribution presents
  the theoretical foundations of a Failure-Oriented Multi-scale variational
  Formulation (FOMF) for modeling heterogeneous softening-based materials u
 ndergoing strain localization phenomena. The multi-scale model considers t
 wo coupled mechanical problems at different physical length scales\, denot
 ed as macro and micro scales\, respectively. Every point\, at the macro sc
 ale\, is linked to a Representative Volume Element (RVE)\, and its constit
 utive response emerges from a consistent homogenization of the micro-mecha
 nical problem.\nAt the macroscopic level\, the initially continuum medium 
 admits the nucleation and evolution of cohesive cracks due to progressive 
 strain localization phenomena taking place at the microscopic level and ca
 used by shear bands\, damage or any other possible failure mechanism. A co
 hesive crack is introduced in the macro model once a specific macroscopic 
 failure criterion is fulfilled.\nThe novelty of the present Failure-Orient
 ed Multi-scale Formulation is based on a proper kinematical information tr
 ansference from the macro-to-micro scales during the complete loading hist
 ory\, even in those points where macro cracks evolve. In fact\, the propos
 ed FOMF includes two multi-scale submodels consistently coupled:(i) a Clas
 sical Multi-scale Model (ClaMM) valid for the stable macro-scale constitut
 ive response.(ii) a novel Cohesive Multi-scale Model (CohMM) valid\, once 
 a macro-discontinuity surface is nucleated\, for modeling the macro-crack 
 evolution.\nWhen a macro-crack is activated\, two important kinematical as
 sumptions are introduced: (i) a change in the rule that defines how the in
 crements of generalized macro-strains are inserted into the microscale and
  (ii) the Kinematical Admissibility concept\, from where proper Strain\nHo
 mogenization Procedures are obtained. Then\, as a consequence of the Hill-
 Mandel Variational Principle and the proposed kinematical assumptions\, th
 e FOMF provides an adequate homogenization formula for the stresses in the
  continuum part of the body\, as well as\, for the traction acting on the 
 macrodiscontinuity surface.\nThe assumed macro-to-micro mechanism of kinem
 atical coupling defines a specific admissible RVE-displacement space\, whi
 ch is obtained by incorporating additional boundary conditions\, Non-Stand
 ard Boundary Conditions (NSBC)\, in the new model. A consequence of introd
 ucing these Non-Standard Boundary Conditions is that they guarantee the ex
 istence of a physically admissible RVE-size\, a concept that we call throu
 gh the paper "objectivity" of the homogenized constitutive response.\nSeve
 ral numerical examples are presented showing the objectivity of the formul
 ation\, as well as\, the capabilities of the new multi-scale approach to m
 odel material failure problems. In addition\, the application of the prese
 nt formulation in the context of modeling biological tissues is discussed.
LOCATION:MA A1 10
STATUS:CONFIRMED
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