Fatigue crack closure determination by means of finite element analysis

Zapatero, J.; Moreno, B.; González-Herrera, Antonio

doi:10.1016/j.engfracmech.2007.02.020

Cited by 46 publications

(29 citation statements)

References 18 publications

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“…In this section, the different parameters that affect the model are briefly presented and their influence on the estimations of the opening and closure stresses obtained are analysed. Detailed information regarding the methodology developed and used has been previously reported 2,26 . ABAQUS and ANSYS commercial FE software have been used in different steps of this study.…”

Section: Modelling Methodsologymentioning

confidence: 99%

Numerical study of the effect of plastic wake on plasticity‐induced fatigue crack closure

González-Herrera

Zapatero

2009

Fatigue Fract Eng Mat Struct

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A B S T R A C T Fatigue crack closure is strongly influenced by the plastic wake developed because of the action of precedent cycles. It is related to the load sequence and is an additional difficulty for its determination. Finite-element method has been an alternative for the study of crack closure, commonly in constant-amplitude loading. However, such analyses are complex and computationally expensive, the length of the wake simulated being a critical parameter. In this paper, a comprehensive study of the effect of the plastic wake in fatigue crack closure is made. It is structured in two parts: one regarding the correct numerical modelling process and the other focussed on the influence of the wake under moderate variable-amplitude loading. After a brief description of the numerical methodology, results for different wake lengths are reported. The plastic wake is modelled with a new approach in which the final crack tip is fixed. Information regarding potential error is provided. Second, the load sequence effect is discussed. Crack closure is obtained for several load ratios, with wakes developed with different stress ratios. This permits the analysis of the influence of the load sequence over the crack-driving force compared with constant-amplitude loading.Keywords crack growth; fatigue crack closure; finite-element analysis; plastic wake. N O M E N C L A T U R Ea = crack length K I = stress intensity factor in mode I K max = maximum stress intensity factor K min = minimum stress intensity factor K ttop = crack opening, tip tensile criterion K ttcl = crack closure, tip tensile criterion K ncop = crack opening, node contact criterion K nccl = crack closure, node contact criterion K tt = crack closure/opening, tip tensile criterion K nc = crack closure/opening, node contact criterion

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Section: Modelling Methodsologymentioning

confidence: 99%

Numerical study of the effect of plastic wake on plasticity‐induced fatigue crack closure

González-Herrera

Zapatero

2009

Fatigue Fract Eng Mat Struct

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“…Significant differences in opening load may be obtained due to nonlinearity or noise in the measurement system, choice of measurement location (close to or remote from the crack tip), or data analysis procedure 10 . Complexities also exist for predicting K open using Dugdale strip yield models that are modified to include plastic deformation at the crack tip and in the crack wake 12–16 or elastic plastic finite‐element analyses 7,17–21 . Such models often entail highly refined meshes and great computational expense, and results can vary significantly depending on mesh density, crack advance per cycle, plastic material hardening assumptions, and the methodology and definition of closure used in the analysis.…”

Section: Introductionmentioning

confidence: 99%

Fatigue crack growth through a residual stress field introduced by plastic beam bending

Jones

Dunn

2008

Fatigue Fract Eng Mat Struct

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A B S T R A C TWe present predictions and measurements of fatigue crack growth rates in plastically bent aluminium 2024-T351 beams. Beam bending and fatigue were carefully controlled to minimize factors other than residual stress that could affect the fatigue crack growth rate, such as large plastic strains or residual stress relaxation. The residual stress introduced by bending was characterized by a bending method and by the slitting method, with excellent agreement between the two methods. Crack growth rates were predicted by three linear elastic fracture mechanics (LEFM) superposition based methods and compared to experimental measurements. The prediction that included the effects of partial crack closure correlated with experimental data to within the variability normally observed in fatigue crack growth rate testing of nominally residual stress free material. Therefore, we conclude that crack growth through residual stress fields may be predicted using the concept of superposition as accurately as crack growth through residual stress free material, provided that the residual stress is accurately known, the residual stress remains stable during fatigue, the material properties are not changed by the introduction of residual stress, and that the effect, if any, of partial crack closure is taken into account. a = crack length B = specimen thickness da/dN = fatigue crack growth rate h(x,a) = weight function K A = stress intensity factor due to applied external forces K max = applied stress intensity factor at P max K min = applied stress intensity factor at P min K ssy = applied stress intensity factor at which small scale yield criteria is violated K open = the stress intensity factor due to P open K R = stress intensity factor due to residual stress K T = total stress intensity factor K T max = total stress intensity factor at P max K T min = total stress intensity factor at P min K T ssy = total stress intensity factor at which small scale yield criteria is violated

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“…Ref. [26][27][28][29]. In addition to its conceptual sim plicity for simulating crack propagation along predicted paths un der cyclic loading, the node-release technique has the major advantage of avoiding time consuming re-meshing procedures.…”

Section: General Conceptsmentioning

confidence: 99%