On the behavior of small fatigue cracks in commercial aluminum-lithium alloys

Rao, K. T. Venkateswara; Yu, W.; Ritchie, R.O.

doi:10.1016/0013-7944(88)90105-1

Cited by 58 publications

(10 citation statements)

References 22 publications

(13 reference statements)

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“…Examples of this can be seen in Figures 17 and 22 and also in Appendix D in [7]. (To the best of the author's knowledge the paper by Rao, Yu and Ritchie [95] was one of the first papers to reveal that the growth of short cracks in aerospace quality aluminium and aluminium-lithium alloys often took a form similar to that shown in Figures 17 and 22.)…”

Section: Implications For Small Crack Growthmentioning

confidence: 87%

Crack Growth From Naturally Occurring Material Discontinuities

Jones

Peng

McMillan

2018

Aircraft Sustainment and Repair

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All repairs to airframes now need to be assessed as to their effect on the damage tolerance the aircraft. To this end this Chapter first discusses difference between the analysis tools needed for ab initio design and aircraft sustainment. It is shown that using small or physically short crack da/dN versus ∆K data results in reduced through life costs and increased aircraft availability. The tests procedures needed to validate composite, or supersonic particle deposition (SPD), repairs to operational aircraft are also discussed as is their relationship to the ASTM fatigue test standard E647-13a. This leads to an examination of the problem of crack growth from small naturally occurring material discontinuities under operational load spectra. A range of tools are available to account for crack growth in operational aircraft and several such tools are discussed, 2 Reference [2] also provides an historical perspective as to how the military, the Federal Aviation Administration (FAA) and industry have dealt with these threats. 3 Widespread fatigue damage (WFD) is defined [11] as the simultaneous presence of cracks at multiple structural locations that are of sufficient size and density such that the structure will no longer meet the residual strength requirements of FAR section §25.571(b). 4 Damage tolerance requirements were not adopted by the FAA until 1978, see [12]. 5 Limit of validity-The period of time (in flight cycles, flight hours, or both) up to which widespread fatigue damage will not occur in the airplane structure.

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Section: Implications For Small Crack Growthmentioning

confidence: 87%

Crack Growth From Naturally Occurring Material Discontinuities

Jones

Peng

McMillan

2018

Aircraft Sustainment and Repair

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“…Crack closure was proposed and has been used as a complementary parameter to explain the effect of plastic deformation on FCG relations. It has been used to explain the effects of stress ratio, overloads, short cracks and specimen thickness . Crack closure has been determined using experimental, numerical or analytical approaches .…”

Section: Introductionmentioning

confidence: 99%

Fatigue crack growth modelling based on CTOD for the 7050‐T6 alloy

Antunes

Branco

Prates

et al. 2017

Fatigue Fract Eng Mat Struct

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The plastic crack tip opening displacement (CTODp) is considered to replace ΔK in the study of fatigue crack propagation. The cyclic plastic deformation of the 7050‐T6 aluminium alloy was determined experimentally and modeled analytically. Then, a three‐dimensional elastic–plastic numerical model which included crack growth was developed in order to predict the plastic CTOD for different loading conditions. In a parallel study, crack growth rates were determined experimentally in M(T) specimens with a thickness of 6 mm. A relation was subsequently established between da/dN and plastic CTOD for the 7050‐T6 aluminium alloy, independent of stress ratio, showing that the CTOD is a viable alternative to ΔK in the analysis of fatigue crack propagation.

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“…Crack closure is the contact of the fracture surfaces during a portion of the load cycle, which affects the local stress and plastic deformation fields near the crack tip and, therefore, the micromechanisms responsible for fatigue propagation [2]. Crack closure was able to explain the influence of mean stress in both regimes I and II of crack propagation [2,3], the transient crack growth behaviour following overloads [4], the growth rate of short cracks [5] and the effect of thickness [6,7], among other aspects.…”

Section: Introductionmentioning

confidence: 98%

Finite element meshes for optimal modelling of plasticity induced crack closure

Antunes

Camas

Correia

et al. 2015

Engineering Fracture Mechanics

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The main goal here is to optimise the finite element mesh used to predict plasticity inducedcrack closure (PICC). A numerical model was developed for a M(T) specimen made of6016-T4 aluminium alloy. The parameters studied were the size of most refined region perpendicularly to crack flank (ym) and along propagation direction (xr), the size of finite elements near crack tip (L1) and the vertical size of refinement close to crack flank (yA/B). A maximum size of about 1.3 mm was found for ym, but a smaller value has a limited impact on PICC. An analytical expression was proposed for xr, dependent on DK and Kmax. An optimumvalue seems to exist for L1.

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On the behavior of small fatigue cracks in commercial aluminum-lithium alloys

Cited by 58 publications

References 22 publications

Crack Growth From Naturally Occurring Material Discontinuities

Crack Growth From Naturally Occurring Material Discontinuities

Fatigue crack growth modelling based on CTOD for the 7050‐T6 alloy

Finite element meshes for optimal modelling of plasticity induced crack closure

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