Tese: 3D Numerical Elastoplastic Analysis of Stress and Strain Distributions Around Crack Tips
Aluno(a) : Mateus Bastos NeivaOrientador(a): Ivan Menezes
Área de Concentração: Mecânica Aplicada
Data: 05/05/2021
Link para tese/dissertação: https://doi.org/10.17771/PUCRio.acad.55076
Resumo: In structure life prediction analysis occurrence of crack defects are of paramount importance to be considered. Basic studies using the Linear Elastic Fracture Mechanics approach shows that Stress Intensity Factor (SIF) parameter controls Fatigue crack growth (FCG). However, overloads may induce material “memory effects” that delay, arrest or accelerate FCG rate, a behavior not described by considering a single elastic parameter. To account for service variable amplitude loadings, the use of a prescribed stress-strain distribution has been proposed, in recent research studies, as the driving force of FCG using the critical damage approach. Due to the assumptions considered in the analytical derivations, the solutions provided by the method violate important equilibrium and compatibility conditions specially as using an idealized singular stress-strain field at the crack front region. In this work a comprehensive review of the recently published analytical results for solutions under the elastic and elastoplastic material behavior regimens are presented: Williams and HRR with singular stress distribution field and Creager-Paris with a non-singular stress field, but with material elastic approach. These solutions are compared, throughout the study, to results obtained from the numerical analysis using a 3D finite element discretization with elastoplastic von Mises yielding criteria employed for the modeling of the crack tip blunt and some comprehensive conclusions are derived regarding application limits of the theoretical models as well as the required extent of the numerical model representation. In addition to monotonic increasing applied loads, unloading was also considered in the numerical analysis, although no reference to this condition is present in the literature considering the analytical approach. For the numerical simulations considered elastoplastic algorithms were implemented in a plugin based framework.