Finite element and analytical modelling of crack closure due to repeated overloads

Variable amplitude fatigue crack growth behavior — a short overview

“…For double overload interactions, Ref. [139] observed that crack closure influence of an initial overload upon the unloading conditions of a second overload can explain much of the observed enhancement in crack growth retardation; however, for successive (repeated) overloads in plane strain, a the critical influence of in-plane constraint arises to attenuate closure interactions.…”

“…The studies of Parry and Kamp et al, are further extended by Refs. [138,139] considering wider ranges of crack geometry, ΔK (BL) (baseline stress intensity factor range), and overload (single and periodic) effects, to elicit a quantitative micromechanical understanding of RICC and overloads. Results from finite element modelling of plasticity-induced crack closure (PICC) and roughnessinduced crack closure (RICC) of fatigue cracks subjected to single overloads showed that the effects of L/r p ratios on RICC, where L and rp represent crack asperity length and plastic zone size, respectively, are seen to be functionally similar to results presented previously for constant amplitude fatigue loading [134], particularly in the saturation of the influence of RICC for L/r p(OL) ≥ 1, where r p(OL) is the overload plastic zone size [138].…”

A short summary on finite element modelling of fatigue crack closure

“…Refs. [52,53,[56][57][58][59] adopted Q4 elements, which use the selectively reducedintegration technique (whereby reduced integration was used for volumetric strain, and full integration for deviatoric strain). Parry specifically verified that these elements could model the incompressible material behavior under plane strain.…”

Strip yield modelling of fatigue crack under variable amplitude loading

“…[17] studied deformation characteristics of periodic overloads and found that differential surface profiles (differences in crack surface displacements after and before overloads) increased with decreasing separation of overloads. It is appropriate to note that to the best of the authors' knowledge only authors' reports [10,29] have been found on plane strain FE analyses subjected to periodic overloads with emphasis on the effect of overload spacing on closure levels. In the analytical front, several attempts have been reported to model PICC (plasticity induced crack closure) effects by modifying the established Dugdale strip yield model [30] to leave plastically deformed material in a propagating crack wake [31][32][33].…”

“…While most studies made on reported periodic overloads are based on experimental approaches, a few finite element (FE) and analytical studies exist, particularly for plane stress situations [10,17,20,25,29]. Refs.…”