Fatigue crack propagation and threshold for shallow micro-cracks under out-of-phase multiaxial loading in a gear steel

Beretta, S.; Foletti, S.; Valiullin, Khaydar

doi:10.1016/j.engfracmech.2010.05.015

Cited by 28 publications

(12 citation statements)

References 19 publications

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“…In the 3.5% NiCrMoV steel, Tong et al 72 reported ΔK III,th ≈ 10.1 MPa m 1/2 (R = À1) and ΔK III,th ≈ 8.1 MPa m 1/2 (R = 0. Beretta et al 73 reported ΔK III,th ≈ 9.2 MPa m 1/2 (R = À1) for a gear steel in torsion. In aluminium alloys, Merati et al 71 determined ΔK III,th ≈ 6.1 MPa m 1/2 for the 7075-T6 alloy and ΔK III,th ≈ 3 MPa m 1/2 for the 2014-T6 alloy.…”

Section: Mode IIImentioning

confidence: 99%

“…In aluminium alloys, Merati et al 71 determined ΔK III,th ≈ 6.1 MPa m 1/2 for the 7075-T6 alloy and ΔK III,th ≈ 3 MPa m 1/2 for the 2014-T6 alloy. Beretta et al 73 reported ΔK III,th ≈ 9.2 MPa m 1/2 (R = À1) for a gear steel in torsion. Murakami et al 28 measured ΔK III,th = 10.6 MPa m 1/2 (=ΔK II,th ) in the 0.47% carbon steel (JISS45C) by observing the sizes of semi-elliptical mode II + III cracks initiating the factory-roof morphology.…”

Section: Mode IIImentioning

confidence: 99%

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Near‐threshold behaviour of shear‐mode fatigue cracks in metallic materials

Pokluda

Pippan

Vojtek

et al. 2013

Fatigue Fract Eng Mat Struct

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This review paper presents a brief state‐of‐the art of the research on long fatigue shear‐mode cracks and describes some recent results on effective crack growth thresholds and mode I branching conditions achieved by the authors for ARMCO iron, titanium with two different microstructures, nickel and stainless steel. A special technique for preparation of fatigue precracks enabled us to substantially suppress the crack closure (friction) effects at the beginning of the experiment, and the measured threshold values could be considered to be very close to the effective ones. In all investigated materials, the effective thresholds under the remote mode II loading were found to be about 1.7 times lower than those under the remote mode III loading. Effective thresholds under mode II loading of investigated materials were found to follow a simple formula assembled by the shear modulus G, the magnitude of Burgers vector b and a goniometrical function nα of the mean deflection angle that depends on the number of available crystallographic slip systems. These quantities determine the intrinsic material resistance to mode II crack propagation at the threshold. A simple criterion for mode I branching in terms of effective threshold values well reflects a transition from the shear‐mode to the opening‐mode controlled crack propagation at the threshold. The associated transition deflection angle of 40° is a material independent constant.

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Section: Mode IIImentioning

confidence: 99%

Section: Mode IIImentioning

confidence: 99%

Near‐threshold behaviour of shear‐mode fatigue cracks in metallic materials

Pokluda

Pippan

Vojtek

et al. 2013

Fatigue Fract Eng Mat Struct

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“…The condition for crack propagation is the following: where Δ K II th is the mode II propagation threshold. Beretta et al 33,34 . made some experiments of mode III and mixed mode (I + III) propagation on the SAE 5135 steel, giving crack propagation diagrams from which an estimation of the mode II propagation constants was deduced, on the basis of the physical similarity of mode II to mode III mechanism 25 .…”

Section: Application To An Experimental Casementioning

confidence: 99%

“…In particular, as the threshold Δ K II th is concerned, it was estimated on the basis of the mode III threshold Δ K III th given in Ref. [34] from mixed mode tests, not from pure mode III tests: in fact, as explained by the authors themselves, in mixed mode tests the Δ K III th is probably less affected by friction between crack faces, as the compression stress imposed in the crack region smoothed the crack faces in the early cycles, lowering friction with respect to pure mode III tests.…”

Section: Application To An Experimental Casementioning

confidence: 99%

A numerical approach to subsurface crack propagation assessment in rolling contact

Mazzù

2013

Fatigue Fract Eng Mat Struct

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Subsurface crack mode II propagation parallel to the contact surface is a damage mechanism leading to dramatic failure in many components subjected to cyclic loading. A weight function (WF) was elaborated for calculating the applied mode II stress intensity factor (SIF) of a crack in a two‐dimensional half‐space in plane strain condition, for crack completely closed and frictionless contact between the crack faces. With respect to other methods, the WF allows faster SIF calculation, thus being suitable for simulation of many repeated load cycles and fatigue crack propagation. The WF was applied for simulating a case of rolling contact experiments found in the literature, and good agreement between experimental and numerical results was obtained, showing the effectiveness of the WF method in damage tolerant design.

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“…This is reasonable from a physical perspective because the tensile stress component, which opens the crack, will certainly promote the conversion of cyclic plastic deformation into crack extension [8]. At the macro level, crack kinking, bifurcation and branching are influenced by micro-structural irregularities, load effects (global and local multiaxial stress state, spectrum loading), and environmental factors [9][10][11][12][13]. Though, the T39 temper was said to account for the fracture toughness improvement, there is no evidence found in the literature that the T39 temper will contribute to the macroscopic crack path change with respect to those of other Al-Cu-Mg alloys, such as 2024-T351 and 2524-T3.…”

Section: Introductionmentioning

confidence: 99%

Mechanism of crack branching in the fatigue crack growth path of 2324-T39 Aluminium alloy

Lu¹,

Bao

Zhang³

et al. 2015

Frattura Ed Integrità Strutturale

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The crack growth behavior in 2324-T39 aluminium alloy was experimentally investigated. Two types of crack branching were observed. The mechanism of an uncommon crack branching which results from the link up of secondary crack with the main crack was focused on. The crack paths were observed with optical microscope and in-situ SEM. Finite element crack tip simulation was performed to investigate the relationship between plastic zone size and the location of the secondary crack. Tests and analysis results indicate that the secondary crack initiates near the plastic zone boundary and from the subsurface. The mechanism of this kind crack branching relates to the interaction of grain size and plastic zone size.

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Fatigue crack propagation and threshold for shallow micro-cracks under out-of-phase multiaxial loading in a gear steel

Cited by 28 publications

References 19 publications

Near‐threshold behaviour of shear‐mode fatigue cracks in metallic materials

Near‐threshold behaviour of shear‐mode fatigue cracks in metallic materials

A numerical approach to subsurface crack propagation assessment in rolling contact

Mechanism of crack branching in the fatigue crack growth path of 2324-T39 Aluminium alloy

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