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Wanhill, R.J.H. (author)
Plight simulation fatigue crack propagation tests with gust spectrum loading were carried out on 2024-T3/carbon-epoxy, 7475-T761/carbon-epoxy and Ti-6Al-4V/carbon-epoxy laminates with nominal weight savings of 30% as compared to equivalent 2024-T3 panels. The performance of the 2024-T3/ carbon-epoxy laminates was much superior to those of the...
report 1977
document
Wanhill, R.J.H. (author)
report 1977
document
van Gestel, G.F.J.A. (author)
In this report an attempt is made to give an overview of the various aspects involved in a fracture surface investigation, stating with a definition of fractography and why it is done. Then the equipment needed is discussed, including stereo-microscopes, optical microscopes, transmission and scanning electron microscopes, and micro-analysis...
report 1977
document
Wanhill, R.J.H. (author)
This paper concisely reviews and discusses (1) metallurgically cleaner alloys like -2124, 2048 and 7475, (2) potential application of 7000 series alloys in tension panels, (3) development of high strength stress corrosion resistant thick section materials like 7010, 7049 and 705O, (4) powder metallurgy 7000 series alloys with high strength and...
report 1977
document
Wanhill, R.J.H. (author)
Flight simulation fatigue crack propagation tests were carried out on 2024-T3, 7475-T761 and mill annealed Ti-6A1-4V sheet in thicknesses up to 3 nim and representative for traJisport aircraft lower wing skin stiffened panels of end load capacities 1.5 and 3 MN/m. There was a significant effect of sheet thickness on crack propagation. Thinner...
report 1977
document
Wanhill, R.J.H. (author)
Flight simulation fatigu-e crack propagation tests were carried out on 2024-T3, 7475-T761 and mill annealed Ti-6A1-4V sheet in thicknesses up to 3 miri and representative for transport aircraft lower wing skin stiffened panels of end load capacities 1.5 and 3 MN/m. The performance of 2024-T3 was much superior, owing mainly to greater retardation...
report 1977
document
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
document
Wanhill, R.J.H. (author), Schra, L. (author)
The effects of flat to slant fracture transitions on flight simulation fatigue crack propagation in specimens of 7O5O aluminium alloy forgings are discussed. For specimens containing flat, shearlipped, or full slant fractures at similar crack lengths the crack resistance (R curve) approach appears to provide an explanation for differences in the...
report 1976
document
't Hart, W.G.J. (author)
Residual strength tests have heen performed, on 300 mm wide centrecracked panels of various thicknesses, at room temperature and at -50 C. During the tests, stable crack growth was filmed and recorded with the electric potential method. Fracture toughness was determined using the method of Feddersen.
report 1976
document
Vlieger, H. (author)
Past experience has shown that during the operational life of an aircraft structure cracks or failures may arise in different structural components. In future designs the designer must be able on the one hand to restrict the occurrence of cracks by a careful detail design and on the other hand to guarantee some specified life of the aircraft if...
report 1976
document
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
document
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
document
Hartman, A. (author)
SEN specimens of 70T5 alloy loaded in bending have been used to determine time to failure and the crack propagation rate as a function of K, the stress intensity factor, and of the electrical potential in 3 wt % aqueous solutions of NaCl, NaBr and Nal with p values of 3 and 7. The SC tests were supplemented by potentio-kinetic polarization tests...
report 1976
document
Vlieger, H. (author)
Residual strength tests were carried out on center-cracked panels with a 2024-T3 or 7075-T6 skin and provided with eccentric stiffeners of practical design. The stiffeners were riveted to the skin. The material of the stiffeners was 7075-T6. In some cases the stiffeners were combined with Ti-alloy crack stoppers. On the basis of the test results...
report 1976
document
Schra, L. (author), van Leeuwen, H.P. (author)
The effect of variety of heat treatments on various engineering properties was studied with the aim to derive an optimum heat treatment. The engineering properties comprised Vickers hardness, short-time tensile strength, fatigue crack propagation resistance, fracture toughness and stress corrosion resistance. The test results were compared with...
report 1976
document
't Hart, W.G.J. (author)
Some residual strength tests have been performed on 610 mm wide centre-cracked panels at a temperature of -50 C, in order to examine whether equal Ke values are obtained as for 300 mm wide panels, tested at -50°C. This work is a continuation of the residual strength investigation reported in NLR TR 76103 and NLR TR 75168.
report 1976
document
'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
document
't Hart, W.G.J. (author), Jacobs, F.A. (author), Nassette, J.H. (author)
report 1975
document
Broek, D. (author)
The growth of fatigue cracks emanating from holes was studied employing 2024-T3 alclad sheet specimens. Both symmetric and asymmetric cases were considered. Crack growth is compatible with the stress intensity factor derived by Bowie and also with the stress intensity factor derived from the simple engineering approach that considers the hole...
report 1972
document
Schijve, J. (author)
report 1972
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