Plastic CTOD as fatigue crack growth characterising parameter in 2024‐T3 and 7050‐T6 aluminium alloys using DIC

Vasco-Olmo, J.M.; Garrido, Francisco; Antunes, F.V.; James, M.N.

doi:10.1111/ffe.13210

Cited by 20 publications

(11 citation statements)

References 22 publications

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“…The CTOD plastic parameter has a physical meaning of its own and can be measured directly 8,9 . The methodology allows simple modeling of the fatigue crack propagation behaviour in different aluminum alloys 10 and 304 L stainless steel 11 …”

Section: Introductionmentioning

confidence: 99%

“…The CTOD plastic parameter has a physical meaning of its own and can be measured directly. 8,9 The methodology allows simple modeling of the fatigue crack propagation behaviour in different aluminum alloys 10 and 304 L stainless steel. 11 These parameters highlight the prominent role of the plasticity at the crack tip on the fatigue crack propagation of metals.…”

Section: Introductionmentioning

confidence: 99%

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Characterisation of the crack tip plastic zone in fatigue via synchrotron X‐ray diffraction

Carrera

Cruces

Kelleher

et al. 2022

Fatigue Fract Eng Mat Struct

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This paper describes a new methodology for characterising the plastic zone ahead of a fatigue crack. This methodology is applied to a set of experimental data obtained by synchrotron X-ray diffraction on a bainitic steel compact tension specimen. The methodology is based on generating the equivalent Von Mises strain field from the X-ray experimental elastic strain maps. Based on the material response, a threshold is then applied on the equivalent strain maps to identify the size and shape of the plastic zone. The experimental plastic zone lies between the plane strain and plane stress Westergaard's bounds but closer to the plane strain theoretical prediction confirming that the volume analyzed is predominantly subjected to plane strain conditions. However, the observed plastic zone has a somewhat flatter shape, extending further from the crack plane but less extended in the crack growing direction.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Characterisation of the crack tip plastic zone in fatigue via synchrotron X‐ray diffraction

Carrera

Cruces

Kelleher

et al. 2022

Fatigue Fract Eng Mat Struct

View full text Add to dashboard Cite

show abstract

“…One method to achieve this is to observe whether the vertical displacement field near the crack tip is continuous and use the critical point at which the displacement suddenly changes as the crack tip position [7]. Vasco-Olmo et al [8][9][10] used the projection of the vertical displacement field on the VOY coordinate plane to find the coordinates of the crack tip in the Y direction. The projection of the vertical displacement field on the VOX is combined with the displacement value corresponding to the coordinate of the crack tip in the Y direction to determine the coordinate value of the crack tip in the X direction.…”

Section: Introductionmentioning

confidence: 99%

Optimisation Method for Determination of Crack Tip Position Based on Gauss-Newton Iterative Technique

Yang

Wei

Liang

et al. 2021

Chin. J. Mech. Eng.

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In the digital image correlation research of fatigue crack growth rate, the accuracy of the crack tip position determines the accuracy of the calculation of the stress intensity factor, thereby affecting the life prediction. This paper proposes a Gauss-Newton iteration method for solving the crack tip position. The conventional linear fitting method provides an iterative initial solution for this method, and the preconditioned conjugate gradient method is used to solve the ill-conditioned matrix. A noise-added artificial displacement field is used to verify the feasibility of the method, which shows that all parameters can be solved with satisfactory results. The actual stress intensity factor solution case shows that the stress intensity factor value obtained by the method in this paper is very close to the finite element result, and the relative error between the two is only − 0.621%; The Williams coefficient obtained by this method can also better define the contour of the plastic zone at the crack tip, and the maximum relative error with the test plastic zone area is − 11.29%. The relative error between the contour of the plastic zone defined by the conventional method and the area of the experimental plastic zone reached a maximum of 26.05%. The crack tip coordinates, stress intensity factors, and plastic zone contour changes in the loading and unloading phases are explored. The results show that the crack tip change during the loading process is faster than the change during the unloading process; the stress intensity factor during the unloading process under the same load condition is larger than that during the loading process; under the same load, the theoretical plastic zone during the unloading process is higher than that during the loading process.

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“…In addition, DIC shows features that influence the entire deformation field of the specimen, for example, the stress dead zone in the centre of MT specimens between the crack tips 23 . These are valuable methods for investigating crack propagation in more detail and for identifying relevant crack driving mechanisms 24–26 …”

Section: Introductionmentioning

confidence: 99%

High‐stress fatigue crack propagation in thin AA2024‐T3 sheet material

Breitbarth

Strohmann

Requena

2020

Fatigue Fract Eng Mat Struct

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Fatigue crack growth in 1.6-mm-thick sheets of aluminium alloy AA2024-T3 was investigated under very high-stress conditions using 950-mm-wide middle tension (MT) specimens. Experiments were conducted by applying uniaxial load ratios R (0.1, 0.3 and 0.5) with the maximum nominal stress of 120 MPa following conditions relevant for aircraft fuselage structures. The experiments were conducted with digital image correlation to determine loading conditions acting on the crack tip. Stable crack growth rates of up to da/dN > 4 mm/cycle and ΔK > 100 MPa√m were reached, and final crack lengths 2a > 500 mm were obtained. High-stress intensity factors cause plastic zone sizes that extend up to approximately 100 mm from the crack tip. The da/dN-ΔK data obtained in this study provide crucial information about the fatigue crack growth and damage tolerance of very long cracks under high-stress conditions in thin lightweight structures.

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Plastic CTOD as fatigue crack growth characterising parameter in 2024‐T3 and 7050‐T6 aluminium alloys using DIC

Abstract: Plastic CTOD as fatigue crack growth characterising parameter in 2024T3 and 7050T6 aluminium alloys using DIC VascoOlmo, JM

Cited by 20 publications

References 22 publications

Characterisation of the crack tip plastic zone in fatigue via synchrotron X‐ray diffraction

Characterisation of the crack tip plastic zone in fatigue via synchrotron X‐ray diffraction

Optimisation Method for Determination of Crack Tip Position Based on Gauss-Newton Iterative Technique

High‐stress fatigue crack propagation in thin AA2024‐T3 sheet material

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