Effect of damage accumulation on the asymptotic behavior of stresses ahead the crack tip

Abstract

The subject of this study is the analysis of mechanical fields associated with a crack tip under creep conditions, taking into account the phenomenon of damage accumulation. The objective of the study is to perform finite element modeling, using the SIMULIA Abaqus software package, of uniaxial tension of a plate with a central horizontal crack under creep conditions, taking into account damage accumulation. For numerical simulation of creep, the Bailey-Norton power law is used. The power law of creep with the help of the user procedure UMAT (User Material) of the SIMULIA Abaqus package was supplemented with the Kachanov-Rabotnov kinetic equation of damage accumulation in a related formulation. In the calculation scheme of finite elements, the crack tip was modeled as a mathematical notch and as a notch with a finite radius of curvature. As a result of the calculations, the distributions of stresses, strains, and continuity under creep conditions were obtained, taking into account the accumulation of damage over time. Radial distributions of continuity, stresses, and strains are plotted over time at various distances from the crack tip. The subject of the study was the consideration of the asymptotic of the stress distribution. As a result of the study, it is shown that in the elastic region the asymptotic corresponds to the distribution under the elastic regime, and in the creep zone the asymptotics of Hutchinson, Rice and Rosengren (HRR-solution) is satisfied for different exponents nof the power law of creep.
 A comparison is made of the radial stress distributions in modeling without taking into account damage and in the case of taking into account damage accumulation. It is shown that the presence of damage significantly changes the asymptotics of the stress field in the vicinity of the crack tip.