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Verhoef, W. (author), van Leeuwen, H.J.C. (author), Clevers, J.G.P.W. (author)
report 1995
document
van Leeuwen, H.P. (author), Groep, F.F. (author), Schra, L. (author), Dam, N. (author)
Test results reported in the literature show that in creep cracking tests at elevated temperature under steady load, the crack growth rate correlates best with the contour integral C*, also called J*, in comparison to other possible parameters. In the case of fatigue at elevated temperature, the crack growth rate correlates best with C* if...
report 1987
document
Groothuizen, R.J.P. (author), van den Berg, J.I. (author), van Leeuwen, W. (author)
Design of robots is an iterative process. Therefore software tools for analysis of different concepts without the need to build hardware models are required. The software tool ROBDYN can be used for analysis of the dynamics properties of a robot. Main constituents are a dynamics algorithm and a facility for the preand postprocessing of data. The...
report 1986
document
van Leeuwen, H.P. (author)
The concept of fugacity is explained. Application of compressibility and fugacity data in hydrogen embrittlement calculations is discussed. Equations of state are reviewed. Compressibility factors and fugacity coefficients are calculated. A best estimate is proposed.
report 1983
document
van Leeuwen, H.P. (author)
The literature concerning the application of fracture mechanics to the growth of creep cracks is discussed. As an introduction it is shown that linear elastic fracture mechanics have been applied successfully to the residual strength of brittle materials crack growth due to stress corrosion and crack growth due to fatigue. Next the methods are...
report 1983
document
ten Have, A.A. (author), Nederveen, A. (author), de Jonge, J.B. (author), van Leeuwen, H.P. (author)
This memorandum presents results of crack propagation tests on notched Alclad 2024-T351 sheet specimens. Two thicknesses were investigated (2 mm and 8 mm), as well as various spectrum modifications and the effect of clustering of severe flights within the test load sequence.
report 1982
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van Leeuwen, H.P. (author), de Rijk, P. (author), Boogers, J.A.M. (author), Huisman, H.N. (author), Wanhill, R.J.H. (author)
Circumferentially notched round specimens of 4340 type steel have been plated in a galvanic bath known to be embrittling. The specimens were reclaimed by stripping and baking. Half the specimens were replated in a non-embrittling bath. Reclamation did not remove all traces of hydrogen embrittlement, but raised the threshold stress to such a...
report 1979
document
Schra, L. (author), van Leeuwen, H.P. (author)
The influence of previous corrosion on the fatigue life was investigated. It was foimd that a slight corrosive attack could drastically reduce the fatigue life. The damaging effect of corrosion was greater for the alloy AA 7050 than for AZ 74.61. It could be established that fatigue cracks initiated from various corrosion pits. A second series...
report 1977
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Schra, L. (author), van Leeuwen, H.P. (author)
The tip of a growing stress corrosion crack was photographed at a magnification of 72 x and at 30 sec. intervals. The crack appeared to grow in a discontinuous manner. Crack reinitiation was preceded or accompanied by gas evolution.
report 1977
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
van Leeuwen, H.P. (author)
Internal hydrogen embrittlement, stress corrosion cracking and external hydrogen embrittlement of high strength steel are analysed. They are found to have lattice decohesion as a common source.
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
van Leeuwen, H.P. (author), Schra, L. (author)
The literature is reviewed with respect to: - tests conducted to investigate crack re-initiation under dynamic load and arrest of a running crack - metallurgical sources of rate effects - available data for aerospace engineering materials - mechanical sources of rate effects, i.e. dynamic crack tip stresses and kinetic energy effects Conclusions...
report 1975
document
Nederveen, A. (author), van Leeuwen, H.P. (author)
Pin-loaded loosely fitting aluminium alloy lugs have been tested in fatigue. Ihe fatigue tests comprised constant amplitude tests at a common mean stress, as well as simplified service simulation tests involving a square wave main load with a high-frequency lowamplitude sinusoidal load superimposed. A variety of anti-fret coatings were compared...
report 1975
document
Nederveen, A. (author), van Leeuwen, H.P. (author)
Pin-loaded loosely fitting aluminium alloy lugs have been tested in fatigue. Ihe fatigue tests comprised constant amplitude tests at a common mean stress, as well as simplified service simulation tests involving a square wave main load with a high-frequency low-amplitude sinusoidal load superimposed. A variety of anti-fret coatings were compared...
report 1975
document
Schra, L. (author), van Leeuwen, H.P. (author)
Data presented by Branger, and indicating an effect of loading rate on residual strength of aluminium alloys and steels, are analysed using fracture mechanics. It is found that the apparent effect is largely or wholly due to the combination of two causes i.e. - the static data pertain to systematically shorter crack lengths than the dynamic...
report 1974
document
van Leeuwen, H.P. (author), Nederveen, A. (author), Ruiter, H.H. (author)
Pin loaded lugs in 2024 T3 have been fatigued under a load compounded from a low frequency load with crenelated wave form and a high frequenoy sinusoidal load. The effects of tightness of fit, clamping pressure and lubrication have been investigated.
report 1973
document
van Leeuwen, H.P. (author), Schra, L. (author)
Material from forgings rejected after cracking in service was given a variety of heat treatments. Material aged to peak hardness was susceptible to SCC at all ageing temperatures. Overageing at temperatures around 160° C imparted a significant increase in SCC resistance while useful strength was retained. An additional one week ageing at 160° C...
report 1973
document
van Leeuwen, H.P. (author)
Delayed failure test results for hydrogenated and cadmium plated specimens, tested by Johnson, Korlet and Troiano, have been analyzed on the basis of equations developed by the author. It is found that in a non-homogeneous stress field the hydrogen diffuses to and accumulates at the elastic-plastic interface. The local hydrogen concentration...
report 1972
document
van Leeuwen, H.P. (author), Schra, L. (author), Boogers, J.A.M. (author)
report 1972
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