Three dimensional elastic-plastic finite element modelling of small fatigue crack growth under a single tensile overload

Variable amplitude fatigue crack growth behavior — a short overview

“…Their results showed qualitative agreement with experimental results, although the FE meshes used were coarse and do not satisfy mesh refinement criteria suggested later [126,127], and the crack growth lengths with the models were small. In the recent years, many reports have been put forward to understand single overload transients using both 2D [128][129][130][131][132][133][134] and 3D [130,135] FE models. FE studies for cracks subjected to double and periodic tensile overloads have been reported by [13,92].…”

The effect of material model in describing mechanism of plasticity-induced crack closure under variable cyclic loading

“…A number of researchers have observed an initial transient fatigue crack growth acceleration of the crack before the retardation effect (Zhang et al (1999), McEvily and Ishihara (2002), Bichler and Pippan (1999), Park and Song (1999) Ward-Close and Ritchie (1988)), while other have only observed the retardation effect (Skorupa (1998), Stephens et al (1999). It is the opinion of the present authors that there must occur an initial instantaneous acceleration during the overload cycle.…”

“…Although there is agreement amongst researchers that a particular mechanism may not be solely responsible for the observed transient behaviour, there is no consensus as to which of the aforementioned mechanisms is primarily responsible for the observed phenomena because the micromechanisms are not completely understood (Zhang et al (1999), Skorupa (1999) and Borrego et al (2003)). For this work, we shall focus on three mechanisms which can be captured by the present 3-D FE model: the residual compressive stresses ahead of the crack tip, the PICC process, and strain hardening ahead of the crack tip.…”

“…Of the investigations conducted on the 3-D modelling of the PICC process, only a very few consider the PICC process under variable amplitude loading conditions. In these works the material model used was either an elastic-perfectly plastic (no strain hardening) (Chermahini et al (1988), Solanki (2002)) or an isotropic hardening (Zhang et al (1999)), which do not consider the Bauschinger effect in cyclic plasticity. There are no known 3-D studies of the application of an underload.…”

A simple analytical crack tip opening displacement approximation under random variable loadings

“…Rigorous calculation of CTOD variation under general variable amplitude loadings should use numerical simulation tools (i.e., finite element method-FEM) to track the nonlinear behavior. Several studies have been proposed to investigate the CTOD variation under several variable amplitude loading spectrums using FEM (Pommier an Risbet 2005;Zhang et al 1999). Due to the high computational cost associated with the very fine FEM simulation, this approach might be useful for mechanism investigation, but is not suitable for practical implementation under arbitrary random variable loadings.…”