Load path effect on fatigue crack propagation in I+II+III mixed mode conditions – Part 1: Experimental investigations

Fremy, Flavien; Pommier, Sylvie; Poncelet, Martin; Raka, Bumedijen; Galenne, Erwan; Courtin, S.; Roux, Jean‐Christophe Le

doi:10.1016/j.ijfatigue.2013.06.002

Cited by 23 publications

(13 citation statements)

References 35 publications

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“…3f are also widely employed in experiments and related finite element analyses (FEAs) hitherto. 59 To load a single specimen simultaneously by remote simple shear in mode II, mode III and mixed mode II + III, a special testing device has been designed and utilized. 3g, were also used in special experiments for determination of effective shear-mode crack growth thresholds.…”

Section: E X P E R I M E N T a L A R R A N G E M E N T S F O R T E S mentioning

confidence: 99%

“…Let us mention that, in addition to aforementioned specimens and setups, a new device for non-proportional I + II + III loading of centrally cracked cruciform specimen was introduced very recently. 59 To load a single specimen simultaneously by remote simple shear in mode II, mode III and mixed mode II + III, a special testing device has been designed and utilized. 16,47 This device transformed tensile forces to the shear stress in circumferentially notched cylindrical bars with an inner diameter d = 12 mm and the outer diameter D = 25 mm ( Fig.…”

Section: E X P E R I M E N T a L A R R A N G E M E N T S F O R T E S mentioning

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: E X P E R I M E N T a L A R R A N G E M E N T S F O R T E S mentioning

confidence: 99%

Section: E X P E R I M E N T a L A R R A N G E M E N T S F O R T E S mentioning

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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“…Fremy et al [6] conducted experiments in non-proportional mixed mode I/II/III loading conditions to investigate the load path effect on fatigue crack growth (FCG) in 316L stainless steel. They applied the 'star' load path to a cruciform specimen containing an inclined crack by using a six-actuator servo-hydraulic testing machine; the addition of mode III loading steps to a mode I/II loading sequence increased the FCG rate even when the crack path was not significantly modified.…”

Section: Introductionmentioning

confidence: 99%

Fatigue Crack Growth under Non-Proportional Mixed Mode Loading in Rail and Wheel Steel Part 1: Sequential Mode I and Mode II Loading

Akama

2019

Applied Sciences

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Fatigue tests were performed to estimate the coplanar and branch crack growth rates on rail and wheel steel under non-proportional mixed mode I/II loading cycles simulating the load on rolling contact fatigue cracks; sequential and overlapping mode I and II loadings were applied to single cracks in the specimens. Long coplanar cracks were produced under certain loading conditions. The fracture surfaces observed by scanning electron microscopy and the finite element analysis results suggested that the growth was driven mainly by in-plane shear mode (i.e., mode II) loading. Crack branching likely occurred when the degree of overlap between these mode cycles increased, indicating that such degree enhancement leads to a relative increase of the maximum tangential stress range, based on an elasto–plastic stress field along the branch direction, compared to the maximum shear stress. Moreover, the crack growth rate decreased when the material strength increased because this made the crack tip displacements smaller. The branch crack growth rates could not be represented by a single crack growth law since the plastic zone size ahead of the crack tip increased with the shear part of the loading due to the T-stress, resulting in higher growth rates.

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“…Several studies have been published based upon experimentation using simple bending specimens, or complex specimens allowing to evaluate the three modes (I + II + III) simultaneously as in Fremy et al Despite these developments, crack propagation under mixed mode loading is still studied using different approaches, namely for the evaluation of an equivalent stress intensity factor.…”

Section: Introductionmentioning

confidence: 99%

“…Studies on mixed mode crack propagation have included approaches to deal with nonlinear shaped cracks, as bent, branched, curved, or zig-zag crack, as discussed by Kitagawa et al 1 For bent and branched cracks, different analytical solutions have been proposed to calculate the stress intensity factors in mode I and mode II, eg, Bilby et al, 2 Lo, 3 and Cotterell and Rice, 4 Crack path is influenced by the crack morphology and irregularities that affect the growth rate and induce combinations of mode I and mode II, 5 typically decreasing the propagation rate for the same stress level, due to the surface interference effects. 6 Several studies have been published based upon experimentation using simple bending specimens, or complex specimens allowing to evaluate the three modes (I + II + III) simultaneously as in Fremy et al 7,8 Despite these developments, crack propagation under mixed mode loading is still studied using different approaches, namely for the evaluation of an equivalent stress intensity factor.…”

Section: Introductionmentioning

confidence: 99%

Mixed mode fatigue and fracture in planar geometries: Observations onK_eqand crack path modelling

Tavares

Reis

Freitas

et al. 2019

Fatigue Fract Eng Mat Struct

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The mixed mode I‐II fatigue and fracture is briefly reviewed, addressing experimental and numerical modelling aspects, and focusing on planar specimens. One major challenge concerns the determination of equivalent stress intensity factor (Keq) in mixed mode situations. Several approaches were compared through the determination of Keq/KI over a wide range of values of KI/KII or KII/KI. Whereas all different approaches converge to the same value as KI/KII increases, the same does not happen for large KII/KI, where differences between values of Keq persist. In the regions of 0 < KI/KII < 2 and 0 < KII/KI < 2, no stable trend of results can be defined. Experimental fatigue crack growth results are presented for Al alloy AA6082‐T6. Compact tension specimens, modified with holes, and four‐point bending specimens under asymmetrical loading promoting mixed mode situations, were subjected to fatigue crack growth tests, where crack path and crack growth rate were measured. The presentation of the fatigue crack growth data was made using a Paris law based upon Keq. Differences in the Paris law constants were found for the different Keq criteria. Recent developments in numerical techniques, as the implementation of the extended finite element method (XFEM) in finite element software packages allows to determine accurately crack paths in mixed mode fracture. This article highlights concepts for mixed‐mode fatigue and fracture and supporting data, identifying challenges still to be overcome.

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Load path effect on fatigue crack propagation in I+II+III mixed mode conditions – Part 1: Experimental investigations

Cited by 23 publications

References 35 publications

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

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

Fatigue Crack Growth under Non-Proportional Mixed Mode Loading in Rail and Wheel Steel Part 1: Sequential Mode I and Mode II Loading

Mixed mode fatigue and fracture in planar geometries: Observations onK_eqand crack path modelling

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Load path effect on fatigue crack propagation in I+II+III mixed mode conditions – Part 1: Experimental investigations

Cited by 23 publications

References 35 publications

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

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

Fatigue Crack Growth under Non-Proportional Mixed Mode Loading in Rail and Wheel Steel Part 1: Sequential Mode I and Mode II Loading

Mixed mode fatigue and fracture in planar geometries: Observations onKeqand crack path modelling

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Mixed mode fatigue and fracture in planar geometries: Observations onK_eqand crack path modelling