Numerical stress intensity factor calculation in flawed round bars validated by crack propagation tests

Lebahn, Jens; Heyer, Horst; Sander, Manuela

doi:10.1016/j.engfracmech.2013.04.013

Cited by 25 publications

(10 citation statements)

References 19 publications

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“…Therefore, it might be negated by the plasticity and damage formation near the surface. For example, in an experimental study of steel circular bars subjected to bending and torsion, the experimental intersection angles were found to be very different from the theoretically predicted critical angles [8].…”

Section: Introductionmentioning

confidence: 79%

The Evaluation of Front Shapes of Through-the-Thickness Fatigue Cracks

Zakavi

Kotousov

Branco

2021

Metals

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Fatigue failure of structural components due to cyclic loading is a major concern for engineers. Although metal fatigue is a relatively old subject, current methods for the evaluation of fatigue crack growth and fatigue lifetime have several limitations. In general, these methods largely disregard the actual shape of the crack front by introducing various simplifications, namely shape constraints. Therefore, more research is required to develop new approaches to correctly understand the underlying mechanisms associated with the fatigue crack growth. This paper presents new tools to evaluate the crack front shape of through-the-thickness cracks propagating in plates under quasi-steady-state conditions. A numerical approach incorporating simplified phenomenological models of plasticity-induced crack closure was developed and validated against experimental results. The predicted crack front shapes and crack closure values were, in general, in agreement with those found in the experimental observations.

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Section: Introductionmentioning

confidence: 79%

The Evaluation of Front Shapes of Through-the-Thickness Fatigue Cracks

Zakavi

Kotousov

Branco

2021

Metals

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“…Regarding the cruciform joint residual stress, it has different effects on the crack initiation and propagation. For the former, the crack initiation, the effect of residual stress is mostly noted in the stress concentration [ 39 ], While in the latter, the crack propagation, its effect is mostly found in the stress intensity factor [ 40 , 41 ]. The relationship between the various calculation steps is shown in Figure 1 , it can be seen that the calculation process consists of three parts.…”

Section: Framework and Experimentsmentioning

confidence: 99%

Fatigue Life of 7005 Aluminum Alloy Cruciform Joint Considering Welding Residual Stress

Wang

Fang

2021

Materials

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An evaluation method is proposed for determining the full fatigue life of aluminum alloy cruciform joint, including the crack initiation and propagation with welding residual stress. The results of simulations have shown that the boundary between the initiation and propagation stage is not constant, but a variable value. The residual stress leads to a significant reduction in both stages, which is more severe on initiation. With considering residual stress, the ratio of crack initiation to total life is below 7%. The effect of residual stress varies with external loading; when external load is lower, the residual stress has a greater effect.

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“…(a) (b) The J-Integral leads to inaccurate results for contour integral evaluation on free surfaces (at the end of the crack front) due to the boundary layer effect [45,46]. This means that the 1/√r-singularity of the stress field on the surface domain is not fulfilled.…”

Section: Single Edge Notch Bending (Senb) Specimensmentioning

confidence: 99%

“…Based on the measured surface crack length, the SIF-range for the surface ΔKS and depth ΔKA is evaluated and used to generate ds/dN-ΔK diagrams for comparing the crack growth behavior of the different specimens. The J-Integral leads to inaccurate results for contour integral evaluation on free surfaces (at the end of the crack front) due to the boundary layer effect [45,46]. This means that the 1/ √ r-singularity of the stress field on the surface domain is not fulfilled.…”

Section: Single Edge Notch Bending (Senb) Specimensmentioning

confidence: 99%

Analytical and Numerical Crack Growth Analysis of 1:3 Scaled Railway Axle Specimens

Šimůnek

Leitner

Maierhofer

et al. 2019

Metals

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This paper deals with experimental fatigue crack propagation in rotating bending loaded round bar specimens as well as an analytical and numerical analysis of the residual lifetime. Constant amplitude (CA) load tests are performed with the surface crack length being evaluated using an optical measurement system. Fracture surfaces are microscopically analyzed to determine crack growth in depth as well as the crack shape. In spite of identical testing conditions, the experimental results show some scatter in residual lifetime, which is mainly caused by different residual stress states. Although X-ray residual stress measurements reveal only minor values, a superposition of the residual stress state with the load-induced stress leads to a significant impact on the residual lifetime calculations, which explains the experimental scatter. Numerical analyses are conducted to consider the residual stress state and their effect on crack propagation by different options. Considering the residual stress distribution in depth within the residual lifetime assessment, the deviation to the most conservative experiment is reduced from +48% to +2%. In conclusion, the results in this paper highlight that it is of utmost importance to consider local residual stress conditions in the course of a crack propagation analysis in order to properly assess the residual lifetime.

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Numerical stress intensity factor calculation in flawed round bars validated by crack propagation tests

Cited by 25 publications

References 19 publications

The Evaluation of Front Shapes of Through-the-Thickness Fatigue Cracks

The Evaluation of Front Shapes of Through-the-Thickness Fatigue Cracks

Fatigue Life of 7005 Aluminum Alloy Cruciform Joint Considering Welding Residual Stress

Analytical and Numerical Crack Growth Analysis of 1:3 Scaled Railway Axle Specimens

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