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't Hart, W.G.J. (author), Nederveen, A. (author), Stoffels, E. (author), Tromp, J. (author)Residual strength tests have been performed on 610 mm wide centre cracked panels. During the tests, stable crack growth was filmed and crack opening displacements were measured. Fracture toughness was determined using the method of Feddersen. Flight simulation fatigue tests were carried out to investigate the crack propagation properties. A...report 1975
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Schra, L. (author), van Leeuwen, H.P. (author), Meulman, A.E. (author)The fatigue crack propagation performance of the alloy AZ 74.61 under manoeuvre spectrum loading was studied. The crack propagation behaviour was also compared with that of the American forging alloy AA 7050, not only for simulated manoeuvre loading but also for simulated gust loading and programme loading. It was found that, at comparable...report 1976
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Schijve, J. (author), Jacobs, F.A. (author), Tromp, P.J. (author)Flight-simulation tests were carried out on sheet specimens notched "by an open hole (Kt = 2.66). The material was 2024-T3 in three conditions; Alclad, bare and chemically milled. The crack initiation period and the crack propagation period were considerably shorter for the Alclad material. The significance of the cladding, both for constant...report 1976
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Schijve, J. (author), Jacobs, F.A. (author), Tromp, P.J. (author)Flight-simulation tests based on a standardized gust load spectrum were carried out in normal air, very dry air and salt water. Specimen thicknesses were t = 2 mm and t = 10 mm, mean stress in flight was 70 or 55 MN/m². In all cases a significant effect of the environment was found. Fatigue lives for t = 10 ram were much shorter than for t = 2...report 1976
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't Hart, W.G.J. (author)Fatigue tests on unidirectional Ca/ep composite material have been performed to investigate whether previous fatigue loading did influence the residual static strength. Residual strength tests were carried out on (0, ± 45)2s and (± 45)2s laminates, while for the (O, ± 45)2s laminate the influence of previous tensile fatigue loading on the...report 1977
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Wanhill, R.J.H. (author)2024-T3, 2048-T851, 7075-T6 and 7475-T761 aluminium alloy sheets were compared for fatigue crack propagation resistance under manoeuvre spectrum and constant amplitude loading. For manoeuvre spectrum loading 7475-T761 was superior overall, and this superiority is most probably due to superior toughness of this alloy. In more detail, 2024-T3 was...report 1978
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Schijve, J. (author), Jacons, F.A. (author), Meulman, A.E. (author)Flight simulation tests on 2024-T3 and 7075-T6 lug specimens indicated significant fatigue life improvements obtained by expanding the holes in accordance with the split-sleeve cold work method. Geometrical distortions induced by the expansion were measured. The significance of residual stresses is analysed with reference to depth of penetration...report 1978
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Lowak, H. (author), de Jonge, J.B. (author), Franz, J. (author), Schutz, D. (author)The Transport Wing Standard programme (TWIST) published in March 1973 is considered to be representative for the load history of the wing root of transport aircraft. A description of the shortened version of this load programme called MINITWIST is given in the present report. In all cases where testing time is a prohibitive factor to use TWIST,...report 1979
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de Koning, A.U. (author)In the present report a simple analytical model for the "behaviour of a centrally cracked strip is proposed. Formulae for computation of compliance, crack opening displacement and effective crack extension force are derived. The model is based on the classical solution for a crack infinite sheet under uniaxial tension. The effect of finite...report 1979
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van der Linden, H.H. (author)The report describes a joint Garteur activity in the field of the prediction of crack propagation under variable amplitude loading. Existing crack propagation models or models under development will be checked with NLR crack propagation data of 202U-T3 Alclad 2 mm sheet material under F-27 Spectrum flight simulation loading. After completion of...report 1979
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Bartelds, G. (author)The applicability of finite element methods to the analysis of cracks was studied in three phases. In the first phase the available methods for the calculation of elastic stress intensity data for cracks of arbitrary shape using finite element techniques were evaluated. The indirect energy release method using virtual crack front variation was...report 1979
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de Jonge, J.B. (author)Due to the development of servo hydraulic fatigue testing machines, fatigue tests under realistic loading conditions have become possible. In these tests, standardized load sequences can be applied. The paper describes the main properties of such sequences, including TWIST and FALSTAFF. Various examples of application of these sequences are...report 1980
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Nederveen, A. (author), de Jonge, J.B. (author), Tromp, P.J. (author)The effects of systematic variations in mean stress level and in spectrum and ground load severity of a flight simulation test programme have been investigated on riveted specimens (fatigue life) and sheet specimens with central saw cut (crack growth). The fatigue life and crack propagation life in Alclad 202U-T3 compared with Alclad TOT5-T6...report 1980
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Wanhill, R.J.H. (author)Flight simulation fatigue crack propagation tests on 202U-T3 and 7475-T761 aluminum alloy sheet were carried out using a gust spectrum representative of the load history of an under wing skin in a transport aircraft. The investigation included tests at several design stress levels and in environments of laboratory air and air plus water spray....report 1980
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de Koning, A.U. (author), van der Linden, H.H. (author)A model for the prediction of growth rates of fatigue cracks in aluminium alloys subjected to service loading conditions is presented. The model is based on an approximate description of the crack opening behaviour and was applied successfully in an analysis of effects of crack growth acceleration and retardation observed experimentally under...report 1981
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Lof, C.J. (author)An application of linear elastic fracture mechanics to 3-dimensional crack growth prediction was developed in two phases. In the first phase finite element techniques for accurate stress intensity (S.I.) calculation were evaluated and the Virtual Crack Extension (V.C.E.)-method was selected for further work. In the second phase the process of...report 1981
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Kolkman, H.J. (author)Differences in the fatigue crack propagation rates of 2024-T351 and 2324-T39 are explicable from differences in microstructures. The slope changes (transitions) in the crack propagation curves are probably associated with the plastic zone sizes being equal to certain microstructural dimensions. As a consequence of different chemical compostion...report 1985
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Gerharz, J.J. (author)Fatigue life assessment of composite structures in fighter aircraft necessitates testing with both mechanical and environmental loading at both coupon and structural element size levels. Testing facilities to run such tests are now available but environmental fatigue testing is expensive and time consuming. An environmental fatigue loading...report 1987
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ten Have, A.A. (author)The RNLN Fleet Air Arm (Marine Luchtvaartdienst) has recently implemented a series of usage monitoring procedures for optimisation of Orion and Lynx operation. Goal is an enhancement of efficiency, economy and safety of the usage of both aircraft systems. Compared to the benefits, the efforts for achieving useful usage monitoring are relatively...report 1991