Some aspects of fatigue thresholds under mode III and mixed mode III and I loadings

Tong, J.; Yates, J. R.; Brown, MW

doi:10.1016/0142-1123(96)00010-2

Cited by 25 publications

(26 citation statements)

References 14 publications

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“…In some cases, however, parallel arrays of semi-elliptical cracks were found to join up by mode I branches to develop the initial stage of the factory-roof morphology (also in accordance with the model 25 ). 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. 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.…”

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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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%

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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“…Whereas a mode III crack due to surface interference propagates 10–50 times slower than a mode I crack at the same nominal stress intensity ranges, 1 the ‘real’ crack growth rate obtained in mode III cracks is in fact higher than that with mode I cracks when the crack surface interference is eliminated 2 . The effects of crack surface interference were also recognized in relation to mixed‐mode crack growth threshold 3 , 4 and fracture strength 5 . The shear mode attenuation introduced by crack surface interference was named by Tschegg 6 as ‘sliding mode crack closure’.…”

Section: Introductionmentioning

confidence: 99%

Modelling of crack surface interference under cyclic shear loads

Abel

1999

Fatigue Fract Eng Mat Struct

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Crack surface interference under cyclic shear loads is studied by an analytical method. The proposed model simulates the effects arising from both the residual stresses and the asperity interactions. A closed‐form and a discrete approach are presented in obtaining the crack surface interference solutions. Backlashes of shear displacements, peeling or group sliding behaviours and induced cyclic mode I stress intensities are predicted under three configurations of residual stress distributions. The effects of a static mode I load, the facet angle and the frictional angle are also analysed. The predicted relationship between the effective shear mode stress intensity range and the R‐ratio is discussed together with the experimentally observed ‘contrasting’ R effects.

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“…Yates and Mohammed 11 proposed a method to predict crack growth rates under mixed Mode (I + III) conditions from pure Mode I fatigue test data based on the local Mode I conditions existing at the crack tip. Tong et al 12 studied fatigue threshold behaviour under Mode III and in‐phase mixed Mode III and Mode I loading conditions in a 3.5%NiCrMoV steel, using V‐notched and pre‐cracked cylindrical bar specimens at load ratios R = 0.1 and −1. Qian et al 13,14 tested mixed mode fatigue crack growth in stainless steels under biaxial loading and found the crack was deflected or branched depending on the initial crack growth angle.…”

Section: Introductionmentioning

confidence: 99%

Experimental study of I + III mixed mode fatigue crack transformation propagation

Qian

2010

Fatigue &Amp; Fracture of Engineering Materials &Amp; Structures

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A B S T R A C T In this paper, compact tension specimens with tilted cracks under monotonic fatigue loading were tested to investigate I + III mixed mode fatigue crack propagation in the material of No. 45 steel with the emphasis on the mode transformation process. It is found that with the crack growth, I + III mixed mode changes to Mode I. Crack mode transformation is governed by the Mode III component and the transformation rate is a function of the relative magnitude of the Mode III stress intensity factor. However, even in the process of the crack mode transformation the fatigue crack propagation is controlled by the Mode I deformation. a x = crack length in horizontal direction (mm) a y = crack length in vertical direction (mm) A = material components ( • /mm) B = thickness of CT specimen (mm) M = material components C = material components ( • /mm) |dθ/da x | = change rate of the angle θ da/dN = fatigue crack propagation rate (mm/cycle) H = width of the notch (mm) W = width of CT specimen (mm) β = tilt angle ( • ) K I = alternating amplitude of Mode I stress intensity factor (MPa·m 1/2 ) K III = alternating amplitude of Mode III stress intensity factor (MPa·m 1/2 ) K e = alternating amplitude of effective stress intensity factor (MPa·m 1/2 ) θ = instantaneous value of the tilt angle β ( • ) σ s = yield strength (MPa) σ b = tensile strength (MPa)

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Some aspects of fatigue thresholds under mode III and mixed mode III and I loadings

Cited by 25 publications

References 14 publications

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

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

Modelling of crack surface interference under cyclic shear loads

Experimental study of I + III mixed mode fatigue crack transformation propagation

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