On the estimation of multiaxial elastoplastic notch stresses and strains under in-phase proportional loadings

Total fatigue life analysis of a nodular cast iron plate specimen with a center notch

“…Neuber's rule is well known for resulting in conservative predictions under near plane strain conditions and for sharp notches. 36,44 With the calibrated value of a U = 1:5, the results are in close agreement with the EP-FEA results, as shown in Figure 5. Based on the analysis of the FEA results, the following proposition has been made for notch fatigue analysis: since the mean stress relaxation effect occurs under a negligible amount of load cycles compared to the crack initiation life, the initial loop obtained by UNR analysis can be shifted to a symmetric position and used for further fatigue life assessment.…”

“…For the sake of simplicity, in engineering calculations, the strain-life analysis should be performed on the stabilized stressstrain loop at the notch tip, which can be estimated with the shift of the initial loop into a zero-mean stress To determine the initial stress-strain loop, the UNR method from Meggiolaro et al 36 has been employed with success in this uniaxial case under plane stress conditions.…”

“…The UNR from Meggiolaro et al 36 can be applied to compute the elastoplastic (EP) stress-strain at notches under proportional multiaxial loading conditions. For fatigue design, fast and automatable solutions for local EP stress-strain computations are significant, which has led to the formulation of several similar approaches, such as Kilambi and Tipton 42 and Ince and Bang.…”

“…2,34 The aim of this study is to model the crack initiation and propagation process in a notched plate specimen from the experiments of Bjo¨rkblad. 35 Crack initiation life is calculated with the Coffin-Manson relationship, whereas nonlinear finite element analysis (FEA) and the unified notch rule (UNR) from Meggiolaro et al 36 are applied for local strain computation. Special attention is given to the mean stress relaxation and strain ratchetting effect, which leads to a change in the local R-ratio.…”

Recent advances on notch effects in metal fatigue: A review

“…Coupling with the plasticity model developed by Jiang and Sehitoglu for multiaxial elasto‐plastic stress‐strain responses analysis, the predicted results are in fairly good agreement with experimental results. Besides, Meggiolaro et al developed a unified notch rule (UNR) and widened its application scopes into multiaxial proportional loading histories simulation, which could reproduce the Neuber or ESED rules and interpolate their notch‐root stress‐strain responses through an accommodation parameter α U . Tao et al developed a new pseudo stress correction approach for local strains estimation of notched structures under multiaxial loadings.…”