Equations for efficient cycle-by-cycle computation of fatigue crack retardation and acceleration due to amplitude changes

Equations for efficient cycle-by-cycle computation of fatigue crack retardation and acceleration due to amplitude changes

Článek WoS

The paper presents an efficient methodology for computation of the evolution of the fatigue crack retardation and acceleration effects due to crack closure during variable amplitude loading. The presented approach can lead to a very effective tool for estimation of residual fatigue life of engineering structures. Conventionally, consideration of variable-amplitude loading is either computationally too demanding, such as in finite element modelling, or challenging to unify the strip-yield model with another computational code. The simple analytical formulae available in literature are based on residual stress, which does not describe correctly the delayed retardation effect and in some cases it can be non-conservative. This work presents simple analytical equations describing the development of the crack closure based on the results of the strip-yield model for amplitude changes at the load ratio R = 0.1. The parabolic function enables simple computation of the maximum crack closure occurring after an overload without running any simulation. The equations also enable computation of crack closure behaviour following amplitude changes with the consideration of various cyclic material properties reflected in the tuneable ratio between the monotonic and cyclic plastic zone sizes.

The paper presents an efficient methodology for computation of the evolution of the fatigue crack retardation and acceleration effects due to crack closure during variable amplitude loading. The presented approach can lead to a very effective tool for estimation of residual fatigue life of engineering structures. Conventionally, consideration of variable-amplitude loading is either computationally too demanding, such as in finite element modelling, or challenging to unify the strip-yield model with another computational code. The simple analytical formulae available in literature are based on residual stress, which does not describe correctly the delayed retardation effect and in some cases it can be non-conservative. This work presents simple analytical equations describing the development of the crack closure based on the results of the strip-yield model for amplitude changes at the load ratio R = 0.1. The parabolic function enables simple computation of the maximum crack closure occurring after an overload without running any simulation. The equations also enable computation of crack closure behaviour following amplitude changes with the consideration of various cyclic material properties reflected in the tuneable ratio between the monotonic and cyclic plastic zone sizes.

Variable amplitude loading; Plasticity induced crack closure; Strip-yield model; Steel

Variable amplitude loading; Plasticity induced crack closure; Strip-yield model; Steel

KUBÍČEK, R.; VOJTEK, T.; POKORNÝ, P.; NÁHLÍK, L.; HUTAŘ, P.

2025

01.10.2024

ELSEVIER

AMSTERDAM

0167-8442

THEORETICAL AND APPLIED FRACTURE MECHANICS

133

104547

Nizozemsko

13

https://www.sciencedirect.com/science/article/pii/S0167844224002969