| Summary: | 碩士 === 中華大學 === 機械工程學系碩士班 === 99 === Two-stage cumulative bending fatigue behavior of the adhesively joint aluminum honeycomb sandwich panels has been experimentally investigated in this study.The loading levels for the two-stage cumulative fatigue experiments were selected from the fatigue baseline of the same kind of honeycomb sandwich panels. The high and low loading levels of the two stage represent the applied loads corresponding to the fatigue lives of 100,000 and 500,000 cycles, respectively. The loading sequence effect and the cycle ratio of the first level were the variables considered in the experimental program. The experimental results show that the sum of the cycle ratios of the two stage is larger than unity when the loading sequence of the two stage is from low to high, while the sum of the cycle ratios of the two stage is less than unity when the loading sequence of the two stage is high-to-low. The results imply that the loading sequence effect exists in the two stage cumulative fatigue tests for the studied sandwich panels and the Miner’s rule fails to predict the remaining cycle ratio of the second level. The indentation of face sheet is the mail failure mode observed in the cumulative fatigue tests, which is the same as that obtained in the constant-amplitude fatigue tests.
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