SEDL / STP / STP714-EB / STP27488S

Effect of Gust Load Alleviation on Fatigue and Crack Growth in ALCLAD 2024-T3

Jonge, JB
Head, Loads Department, and research engineer, National Aerospace Laboratory, Nationaal Lucht en Ruimtevaart Laboratorium, Amsterdam,

Nederveen, A
Head, Loads Department, and research engineer, National Aerospace Laboratory, Nationaal Lucht en Ruimtevaart Laboratorium, Amsterdam,

Pages: 15    Published: Jan 1980

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Abstract

Active controls can be used to reduce gust induced loads on transport aircraft wings. Fatigue tests under flight simulation loading were done on simply notched sheet specimens made of ALCLAD 2024-T3 to assess the fatigue life increase that can be obtained by gust alleviation. Test results did show an important increase in crack initiation life. However, crack propagation life was hardly affected. The observed effect on fatigue life could be reasonably well predicted by Miner type life calculations. Miner type calculations, however, are bound to fail in predicting the effect of spectrum-variations such as deletion of ground-air-ground cycle or small gust cycles.