About the fatigue crack propagation threshold of metals as a design criterion – A review

Zerbst, Uwe; Vormwald, Michael; Pippan, Reinhard; Gänser, Hans-Peter; Sarrazin-Baudoux, C.; Madia, Mauro

doi:10.1016/j.engfracmech.2015.12.002

Cited by 204 publications

(91 citation statements)

References 150 publications

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“…In stage I (the crack-initiation stage), a crack-growth threshold exists. In general, there are two types of thresholds [38]: microstructural and mechanical. The microstructural threshold describes the initiation of micro-cracks at different microstructural features, such as slip bounds and cavities.…”

Section: Stage I: Crack Initiationmentioning

confidence: 99%

Crack Propagation Mechanisms for Creep Fatigue: A Consolidated Explanation of Fundamental Behaviours from Initiation to Failure

Liú

Pons

2018

Metals

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Background-Creep-fatigue damage is generally identified as the combined effect of fatigue and creep. This behaviour is macroscopically described by crack growth, wherein fatigue and creep follow different principles. Need-Although the literature contains many studies that explore the crack-growth path, there is a lack of clear models to link these disparate findings and to explain the possible mechanisms at a grain-based level for crack growth from crack initiation, through the steady stage (this is particularly challenging), ending in structural failure. Method-Finite element (FE) methods were used to provide a quantitative validation of the grain-size effect and the failure principles for fatigue and creep. Thereafter, a microstructural conceptual framework for the three stages of crack growth was developed by integrating existing crack-growth microstructural observations for fatigue and creep. Specifically, the crack propagation is based on existing mechanisms of plastic blunting and diffusion creep. Results-Fatigue and creep effects are treated separately due to their different damage principles. The possible grain-boundary behaviours, such as the mismatch behaviour at grain boundary due to creep deformation, are included. The framework illustrates the possible situations for crack propagation at a grain-based level, particularly the situation in which the crack encounters the grain boundary. Originality-The framework is consistent with the various creep and fatigue microstructure observations in the literature, but goes further by integrating these together into a logically consistent framework that describes the overall failure process at the microstructural level.

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Section: Stage I: Crack Initiationmentioning

confidence: 99%

Crack Propagation Mechanisms for Creep Fatigue: A Consolidated Explanation of Fundamental Behaviours from Initiation to Failure

Liú

Pons

2018

Metals

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“…where is critical crack length, is initial crack length, is geometrical factor, Δ is stress amplitude [18].…”

Section: The Fatigue Residual Life Of the Vibrating Screen Beammentioning

confidence: 99%

Strain modal analysis and fatigue residual life prediction of vibrating screen beam

Zhang¹

2016

J. meas. eng.

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Abstract. The displacement and strain modal analysis of vibrating screen beam is carried out, the results show that the relative deviation of the modal frequencies between intact and damaged beam is small, the displacement mode shapes of the damaged beam have no obvious variation, but the strain mode shapes have mutation peaks at the damaged location for the damaged beam. Therefore, a damage index is defined as the rate of strain modal change between damaged and intact beam. The rate of strain modal change increases with the increasing damage extent of the beam. The initial fatigue crack length is related to the damage extent of the beam; the fatigue crack propagation residual life of the beam is predicted by the Paris law. The results show that the rate of strain modal change is a sensitive and reliable damage index for indicating the damage location and damage extent. The predictions of the damage extent and the crack propagation residual life of the vibrating screen beam are beneficial to dynamic optimization design, which can improve the service life of the vibrating screen.

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“…A recent review of the crack propagations of metal can be found in [17][18][19][20][21][22]. It suggested the small crack as a damage tolerant design criterion before the crack propagates.…”

Section: Introductionmentioning

confidence: 99%

“…It suggested the small crack as a damage tolerant design criterion before the crack propagates. Based on the recent literature found in [13][14][15][16][17][23][24][25], none of those discussed on the sickle-shapes are assumed as crack geometries. The solution of sickleshaped surface crack is hard to find, as it usually occurs for the case of bolt where the crack forms circumferentially around the solid bar.…”

Section: Introductionmentioning

confidence: 99%

Mode I stress intensity factors of sickle-shaped surface cracks in round solid bars under bending moment

Ismail¹

2016

Int. J. Automot. Mech. Eng.

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Sickle-shaped crack may occur on the surface of solid round cylinder under some specific reasons such as design discontinuities or material defects. This type of crack is capable to grow circumferentially around the bar and it is called a sickle-shaped surface cracks. The complete solution of stress intensity factors (SIF) of sickle-shaped surface cracks is hard to find and therefore the objective of this paper is to present the behaviour of these cracks under remotely applied bending moment. In order to understand the role of these cracks, there are seven crack aspect ratios, a/b considered, ranging from 0.0 to 1.2. For each crack aspect ratio, there are six relative crack depths, a/D used ranging from 0.1 to 0.6. ANSYS finite element program is used to model the crack. Stress intensity factor (SIF) which is based on the J-integral is used to characterize the cracks. For relatively shallow cracks (a/D  0.3), the role of SIFs along the crack front is insignificant regardless of a/b. However, for the deeper cracks (a/D > 0.3), the effect of a/b is tremendous on the SIFs. If a/b is increased from 0.0 to 1.2, higher SIFs are obtained around the central compared with the outer regions of the crack fronts. This is due to the fact that the circumferential cracks at both sides of the bar experience lack of mode I opening mechanism compared with the crack faces at the upper side cracks. It is suggested that the phenomena of crack closure are not only caused by the plastic deformation, surface roughness and other related factors but the shape of crack also plays an important role.

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About the fatigue crack propagation threshold of metals as a design criterion – A review

Cited by 204 publications

References 150 publications

Crack Propagation Mechanisms for Creep Fatigue: A Consolidated Explanation of Fundamental Behaviours from Initiation to Failure

Crack Propagation Mechanisms for Creep Fatigue: A Consolidated Explanation of Fundamental Behaviours from Initiation to Failure

Strain modal analysis and fatigue residual life prediction of vibrating screen beam

Mode I stress intensity factors of sickle-shaped surface cracks in round solid bars under bending moment

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