22nd Congress of International Council of the Aeronautical Sciences, Harrogate, UK, 28 August - 1st September, 2000
Paper ICAS 2000-4.4.5

CALENDAR FATIGUE LIFE OF AIRFRAME MATERIALS

B. Wang (1, 2), J. Fan(2), Q. Sun (2), Q. Yang (2)
(1) Xi’an Aircraft Design & Research Institute, Xi’an, PRC (2) Northwestern Polytechnical University, Xi’an, PRC

Keywords: fatigue, airframe, materials

A long-term program to study the calendar fatigue property of airframe materials has being carried on. The specimens of several kinds of material were exposed to an atmospheric environment and planned to do fatigue test after being exposed for 0~15 years. This paper presents the result of the first 4 years. The relation between the fatigue properties and the exposure calendar time is analyzed thoroughly. An approach to predict the calendar fatigue life of structure is developed. Some conclusions are: (1)The mean and the variation coefficient of fatigue life decreases and increases with the elapse of calendar time respectively. (2)The effect of cold expansion to prolong the fatigue life of a hole decreases with the calendar time. (3)Applying a modified Miner’ rule to predict the calendar fatigue life of a structure is practical. (4)It is not correct to use the ordinary fatigue property of material without any deduction to predict the fatigue life over a certain calendar time.

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