Lessons from a fatigue prediction challenge for an aircraft wing shear tie post

Main, Ben; Evans, Richard M.; Walker, K.; Yu, Xibin; Molent, L.

doi:10.1016/j.ijfatigue.2019.02.007

Cited by 40 publications

(28 citation statements)

References 15 publications

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“…This curve is also shown in Figure 4 . Interestingly the Mean- 3σ curve shown in Figure 4 for these size EIDS is close to that given in [ 24 , 25 , 26 ] for the growth of “small” cracks from small near micron size surface discontinuities in 7050-T7451. It is also the same as the values determined in [ 17 ] for the growth of small surface breaking cracks in LPBF Ti-6Al-4V.…”

Section: Implications For the Durability Analysis Of Am Partssupporting

confidence: 81%

Modelling the Variability and the Anisotropic Behaviour of Crack Growth in SLM Ti-6Al-4V

et al. 2021

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The United States Air Force (USAF) Guidelines for the Durability and Damage Tolerance (DADT) certification of Additive Manufactured (AM) parts states that the most difficult challenge for the certification of an AM part is to establish an accurate prediction of its DADT. How to address this challenge is the focus of the present paper. To this end this paper examines the variability in crack growth in tests on additively manufactured (AM) Ti-6Al-4V specimens built using selective layer melting (SLM). One series of tests analysed involves thirty single edge notch tension specimens with five build orientations and two different post heat treatments. The other test program analysed involved ASTM standard single edge notch specimens with three different build directions. The results of this study highlight the ability of the Hartman–Schijve crack growth equation to capture the variability and the anisotropic behaviour of crack growth in SLM Ti-6Al-4V. It is thus shown that, despite the large variability in crack growth, the intrinsic crack growth equation remains unchanged and that the variability and the anisotropic nature of crack growth in this test program is captured by allowing for changes in both the fatigue threshold and the cyclic fracture toughness.

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Section: Implications For the Durability Analysis Of Am Partssupporting

confidence: 81%

Modelling the Variability and the Anisotropic Behaviour of Crack Growth in SLM Ti-6Al-4V

et al. 2021

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“…Whilst the origin of Equation (1) can be traced back to Hartman and Schijve [33], similar equations can be found in [34][35][36][37][38][39], and its link to fractal based crack growth equations is discussed in [40,41]. A range of examples showing how this formulation can be used to study aircraft sustainment related problems are given in [40][41][42][43][44][45][46][47][48][49]. Applications to bridge and rail steels are given in [50][51][52], to polymers in [53] and to bonded wooden joints in [54].…”

Section: Theoretical Considerationsmentioning

confidence: 96%

Requirements and Variability Affecting the Durability of Bonded Joints

et al. 2020

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This paper firstly reveals that when assessing if a bonded joint meets the certification requirements inherent in MIL-STD-1530D and the US Joint Services Standard JSSG2006 it is necessary to ensure that: (a) There is no yielding at all in the adhesive layer at 115% of design limit load (DLL), and (b) that the joint must be able to withstand design ultimate load (DUL). Secondly, it is revealed that fatigue crack growth in both nano-reinforced epoxies, and structural adhesives can be captured using the Hartman–Schijve crack growth equation, and that the scatter in crack growth in adhesives can be modelled by allowing for variability in the fatigue threshold. Thirdly, a methodology was established for estimating a valid upper-bound curve, for cohesive failure in the adhesive, which encompasses all the experimental data and provides a conservative fatigue crack growth curve. Finally, it is shown that this upper-bound curve can be used to (a) compare and characterise structural adhesives, (b) determine/assess a “no growth” design (if required), (c) assess if a disbond in an in-service aircraft will grow and (d) to design and life in-service adhesively-bonded joints in accordance with the slow-growth approach contained in the United States Air Force (USAF) certification standard MIL-STD-1530D.

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“…A feature of this formulation is that it has been shown to be able to accurately perform durability analyses for unrepaired airframes, as well as for cold spray repaired and lased added deposition (LAD) repairs [1,9,26,37,39,[63][64][65].…”

Section: Conflicts Of Interestmentioning

confidence: 99%

Experimental Studies into the Analysis Required for the Durability Assessment of 7075 and 6061 Cold Spray Repairs to Military Aircraft

Jones

Matthews²,

Peng

et al. 2020

Aerospace

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This paper presents an experimental study into the analysis required for the durability assessment of 7075 and 6061 cold spray repairs to military aircraft. To this end, it is first shown that provided the bulk stress in a 7075 cold spray coating can be kept beneath approximately 150 MPa, then the coating should not crack. A range of examples are presented in which the interface between the coating and the substrate only fails subsequent to crack growth in the substrate. We also show that failure of cold spray repaired/coated panels can also be due to the nucleation and growth of cracks in the substructure immediately adjacent to the coated/repaired region. As such, when performing a durability analysis for a cold spray repair, the growth of such small naturally occurring cracks, both at the interface and immediately adjacent to the ends of the coating, need to be accounted for.

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Lessons from a fatigue prediction challenge for an aircraft wing shear tie post

Cited by 40 publications

References 15 publications

Modelling the Variability and the Anisotropic Behaviour of Crack Growth in SLM Ti-6Al-4V

Modelling the Variability and the Anisotropic Behaviour of Crack Growth in SLM Ti-6Al-4V

Requirements and Variability Affecting the Durability of Bonded Joints

Experimental Studies into the Analysis Required for the Durability Assessment of 7075 and 6061 Cold Spray Repairs to Military Aircraft

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