Nova classe de células com descontinuidade forte embutida para análise de propagação de fissuras pelo método dos elementos de contorno

Abstract

Over the past few years there has been a major advance in the numerical study of material failures in solid medium incentived by the increase in available computing resources. Thus, several techniques were created with the objective of ascertaining the behavior of materials subject to overload and, therefore, to predict structural collapse. In this sense, the linear elastic fracture mechanics, the discrete or cohesive models, the smeared crack models, the enhanced continuous models and the continuum strong discontinuity approach stand out. The latter technique, in turn, has been gained increasing prominence because it allows that continuous constitutive models, equipped with a softening law, to be compatible with the presence of discontinuous displacement fields and, consequently, with the emergence of unlimited strains. Thus, the present work adopts the implicit formulation of the boundary element method for two-dimensional material failure analysis using the continuum strong discontinuity approach. The main objective is the elimination of the stress locking phenomenon commonly present in numerical analysis using cells with uniform displacement jumps. These cells are not able to represent the relative rotational movement between their parts that are divided by the discontinuity line, inducing an unreal rigidity in the structural response. In this way, a new class of cells with non-uniform displacement jumps will be created in order to adequately capture the relative rotational movement between the parts of the cell and, therefore, eliminate the stress locking. In addition, an automatic cell generation algorithm that follows the discontinuity line as the failure or bifurcation criteria are reached is used. Finally, the implementation is performed in the INSANE (INteractive Structural ANalysis Environment) system that is developed by the Department of Structural Engineering of the Federal University of Minas Gerais and that follows the object oriented programming paradigm according to the Java language.