Searched for: author:"Schra, L."
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Schra, L. (author), Wanhill, R.J.H. (author)
In 1991 a simple automated stress corrosion testing method called the ASCOR (Automated Stress corrosion Ring) test was developed to test aluminium alloys according to ASTM specification G49. The present investigation concentrated on evaluating two aspects of the test method: The SCC initiation criterion (2 % load decrease). The possibility of...
report 1997
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Schra, L. (author), van der Hoeven, W. (author)
In the aerospace industry there are continuing demands for weight reductions. These demands translate into the need to develop new materials with greater strength and stiffness and/or improved damage tolerance properties. The NLR has followed these developments by conducting experimental programmes to evaluate engineering properties like static...
report 1997
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Schra, L. (author)
An interlaboratory testing programme to evaluate the rising displacement test for stress corrosion crack (SCO growth investigations was carried out within the framework of the "Measurements and Testing" programme of the European Community under BCR contract nr. MATI CT 930038. The contribution of the NLR to the project consisted of testing of...
report 1996
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Wanhill, R.J.H. (author), Schra, L. (author)
An investigation was made of the effect of starter notch geometry on flight simulation fatigue crack growth in three damage tolerant aluminium sheet alloys, 2024-T3, 2091-T84 and 8090-T81. Changing the starter notch geometry resulted in significant differences in initial nonstabilized fatigue crack growth behaviour. However, there was only a...
report 1995
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Wanhill, R.J.H. (author), Schra, L. (author), 't Hart, W.G.J. (author)
This report compares the mechanical properties, fracture toughness and fatigue crack growth properties of the damage tolerant/medium strength aluminium plate alloys 2024-T351, 2324-T39, 8090-T651 and 8090-T8171. The main objective, in view of previous work, was to determine whether damage tolerant 8090-T8171 plate can advantageously replace the...
report 1995
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de Koning, A.U. (author), Schra, L. (author)
In this report the experimental procedure is described and results are given of tests for verification of advanced crack growth prediction models. Testing involved constant amplitude fatigue loading at R = 0.1 and R = 0.5. In a similar test series loading was interrupted at regular intervals for application of overloads or overload/underload...
report 1994
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Schra, L. (author), 't Hart, W.G.J. (author)
Corrosion tests under MASTMAASIS test conditions and alternate immersion constant load stress corrosion tests in a 3.5 % NaCl solution were carried out on 1.6 mm thick sheet material of the Al-Li alloys 2091-T84 and 8090-T81, and on the reference 2024-T3 alloy. Corrosion tests were also carried out on preproduction 2091 sheet. The results of the...
report 1992
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't Hart, W.G.J. (author), Schra, L. (author)
In the framework of the CEC Brite Euram programme on "Investigations on aluminium-lithium alloys for damage tolerant application", the NLR work in Task 3 concentrated on Fracture Toughness. In part I of the investigation residual strength tests were performed on 500 mm wide CCT panels of the Al-Li sheet alloys 2091-T84 and 8090-T81 and on 2024...
report 1992
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Wanhill, R.J.H. (author), Schra, L. (author), 't Hart, W.G.J. (author)
report 1992
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Schra, L. (author), Groep, F.F. (author)
Alternate immersion stress corrosion testing according to ASTM specification G44 has proven to be representative for aluminium alloys in natural environments resembling the actual environmental conditions for aircraft. A simple automated stress corrosion testing method called the ASCOR (Automated Stress COrrosion Ring) test was developed to test...
report 1991
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Schra, L. (author), Wanhill, R.J.H. (author)
Flight simulation fatigue growth tests were done on 1.6 mm thick sheets of the damage tolerant aluminium-lithium (Al-Li) alloys 2091-T84 and 8090-T81 in comparison with the industry standard conventional damage tolerant alloy 2024-T3. The flight simulation load spectrum, the gust spectrum MINITWIST, was used in four versions: untruncated,...
report 1991
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Kolkman, H.J. (author), Schra, L. (author)
The SCC resistances of three damage tolerant aluminium sheet materials were determined by means of the ASCOR (Automated Stress Corrosion Ring) test. The conventional damage tolerant sheet material 2024-T3 was used as reference. The sec resistance of 8090-T81 turned out to be only slightly lower than the sec resistance of 2024-T3. In contrast,...
report 1991
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Schra, L. (author), Kolkman, H.J. (author)
The SCC resistances of three damage tolerant aluminium sheet materials were determined by means of the ASCOR (Automated Stress COrrosion Ring) test. The conventional damage tolerant sheet material 2024-T3 was used as reference. The SCC resistance of 8090-T81 turned out to be only slightly lower than the SCC resistance of 2024-T3. In contrast,...
report 1991
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Wanhill, R.J.H. (author), Schra, L. (author), 't Hart, W.G.J. (author)
report 1991
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Schra, L. (author)
report 1991
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Wanhill, R.J.H. (author), 't Hart, W.G.J. (author), Schra, L. (author)
Since 1984 the NLR has done many fatigue crack growth tests to compare the modern Al-Li alloys 2090, 2091 and 8090 with the conventional damage tolerant alloys 2024 and 2324. Under constant amplitude loading the Al-Li alloy crack growth behaviour is often equivalent or superior to that of the conventional alloys. However, under gust spectrxim...
report 1991
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Wanhill, R.J.H. (author), Schra, L. (author), 't Hart, W.J.G. (author)
The fatigue crack growth properties of several aluminium-lithium (Al-Li) sheet alloys were compared with those of the widely used conventional 2024-T3 alloy. The data, which are relevant to the in-service inspectable damage tolerance regime, were obtained using constant amplitude and flight simulation (gust spectrum) loading. The Al-Li alloys...
report 1991
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Schra, L. (author), 't Hart, W.G.J. (author), Boogers, J.A.M. (author)
Outdoor corrosion and stress corrosion tests were conducted on Al-Li plate and sheet materials for 3 and almost 5 years respectively. The results can be summarized as follows: Corrosion: Peak aged XXXA-T651 (8090-T651) exhibited greater exfoliation corrosion resistance than 2024-T351 and 2324-T39 plate. 2091-T3 and 2024-T3 sheet were found to be...
report 1990
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Schra, L. (author), 't Hart, W.G.J. (author), Boogers, J.A.M. (author)
Outdoor corrosion and stress corrosion tests were conducted on AJl-Li plate and sheet materials for 3 and almost 5 years respectively.
report 1990
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Wanhill, R.J.H. (author), Schra, L. (author), 't Hart, W.G.J. (author)
A comparison is made of the crack resistance (R-curve), fracture toughness and instability behaviour of candidate damage tolerant aluminiumlithium alloys, 2091 and 8090, and the widely used conventional 2024-T3 alloy. The 2091 alloy was in three heat treatment conditions, T8X, TX and TY, all artificially aged. The 8090 alloy was in the T81...
report 1990
Searched for: author:"Schra, L."
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