Influence of the loading path on fatigue crack growth under mixed-mode loading

Doquet, Véronique; Abbadi, M.; Bui, Quang‐Hien; Pons, Adeline

doi:10.1007/s10704-009-9396-6

Cited by 24 publications

(13 citation statements)

References 18 publications

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“…It should be noted, however, that the shear-mode crack growth was associated with many mode I branches along the crack paths that contributed to deceleration and final bifurcation of mode II cracks. In the maraging steel, Doquet et al 69 observed an immediate transition to mode I branch below ΔK II = 15 MPa m 1/2 . The most frequently observed behaviour was a very short coplanar crack growth that was stopped after 10 μm to create a mode I branch of 70 o , although an immediate branching was observed as well.…”

Section: Mode IImentioning

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 IImentioning

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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“…However, due to asperities interlocking and friction, the stress intensity factors computed for a smooth frictionless crack (denoted by K nominal II , K nominal III ) overestimate the effective crack driving force Pinna and Doquet (1999); ; Tschegg and Stanzl (1988); Smith and Smith (1988); Doquet et al (2009);Bertolino and Doquet (2009). Corrections based on a comparison of expected and measured crack face relative sliding displacements had thus to be made.…”

Section: Computation Of Nominal Stress Intensity Factors Along the Crmentioning

confidence: 99%

“…For that purpose, constitutive equations with isotropic and non-linear kinematic hardening fitted to experimental stress-strain curves measured in tension and push-pull for maraging steel and Ti-6Al-4V were used. More details on these equations can be found in Doquet et al (2009);Bertolino and Doquet (2009); .…”

Section: Correction Of Stress Intensity Factors For Crack Face Interamentioning

confidence: 99%

“…The aim of this study is to provide some elements of clarification, bearing in mind that the stress intensity factors computed for a smooth frictionless crack (denoted by K nominal II , K nominal III ) overestimate the effective crack driving force, due to the interlocking and friction of the asperities along the crack surface Pinna and Doquet (1999); ; Tschegg and Stanzl (1988); Smith and Smith (1988); Doquet et al (2009);Bertolino and Doquet (2009). A special effort was thus made to determine the effective stress-intensity factors ( K effectivel II , K effective III ) that should be used to correlate the measured crack growth rates.…”

Section: Introductionmentioning

confidence: 99%

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3D shear-mode fatigue crack growth in maraging steel and Ti-6Al-4V

et al. 2010

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International audienceFatigue crack growth tests in mixed-mode II + III were performed on maraging steel and Ti-6Al- 4V. The 3D evolutions of the crack fronts -measured by SEM after interrupted tests- were analyzed, taking into account the reduction in effective crack driving force by the interlocking and friction of the asperities of the crack surface. Under small-scale yielding conditions, the mixed-mode crack growth rates were found to correlate best with Keff2 II + 1.2Keff2 III in maraging steel, while for Ti-6Al-4V, Keff2 II + 0.9Keff2 III appeared suitable. For extended plasticity, a crack growth prediction method is proposed and validated for Ti-6Al-4V. This method is based on elastic-plastic F.E. computations and application, ahead of each node of the crack front, of a shear-dominated fatigue criterion

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“…At present, experimental FCG investigations are predominantly undertaken for mode I or proportional mixed mode loads. Only a few studies [1][2][3][4][5][6][7][8] focus on non-proportional mixed mode loads. Limited results on A106-93 mild steel [3] reveal that a long and stable shear mode FCG -which is significantly different from the commonly understood open mode FCG -could be produced by non-proportional loads.…”

Section: Introductionmentioning

confidence: 99%

Fatigue crack growth of aluminium alloy 7075-T651 under non-proportional mixed mode I and II loads

Yu¹,

Li²,

Proust³

2016

Frattura Ed Integrità Strutturale

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ABSTRACT. This study aims to investigate fatigue growth behaviour in AA7075-T651 under non-proportional mixed mode I and II loads. Fatigue tests were performed under cyclic tension and torsion using a thin-walled tubular specimen with a key-hole style crack starter. After the generation of a single-side mode I pre-crack, varied forms of mixed mode loads were applied, which in most cases led to a short distance coplanar growth followed by a long and stable crack path deviation. It was found that under most of the non-proportional mixed mode load cases, the direction of the deviated crack path could not be reasonably predicted using the commonly accepted maximum tangential stress criterion. Meanwhile, in some cases, the crack path directions could be approximately predicted using the maximum shear stress criterion. It was also confirmed for the first time that a long, stable and noncoplanar shear mode fatigue crack growth could be produced in AA7075-T651 under non-proportional mixed mode I and II loads.

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Influence of the loading path on fatigue crack growth under mixed-mode loading

Cited by 24 publications

References 18 publications

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

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

3D shear-mode fatigue crack growth in maraging steel and Ti-6Al-4V

Fatigue crack growth of aluminium alloy 7075-T651 under non-proportional mixed mode I and II loads

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