Formulações de modelos constitutivos de microplanos para contínuos generalizados

Abstract

This work describes the non-linear analysis of the quasi-brittle media through the Finite Elements Method, targeting to dene appropriate kinematic and static descriptions to these medias.The limitations of the classical continuum theory, as well as those of the local constitutive models, on the representation of strain localization problems, are pointed out. In addition, are proposed thermodynamically consistent formulations that gather the advantages of the Microplanes model for considering the material's anisotropic behavior together with the Generalized Continuums, that have intrinsic characteristic lengths, being able to describe materials which need to have its microstructure highlighted for the understanding of the structural behavior.Initially, the microplane constitutive model is formulated for the Cosserat continuum and, in one second phase, a renement of the proposed model is presented, with the use of the microstretch continuum.The implementations of the proposed constitutive model are discussed, as well as of those taken as reference, and also all the necessary tools to the complete solution of the nonlinear problem. These implementations are included in the numerical core of the INSANE computing system, a software developed at the Structures EngineeringDepartment of UFMG, that uses the object-oriented programming approach. Numerical simulations are presented. The analysis of the results is followed by a discussion of the adequacy of classic theories and proposed models.