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某直升机旋翼桨叶疲劳试验考核中发生蒙皮断裂,寿命远低于设计要求。分析表明蒙皮模压质量、泡沫对接缝对蒙皮应力影响较小,不足以造成桨叶疲劳试验的提前失效。通过有限元模拟发现蒙皮厚度不均匀导致的应力集中是疲劳试验提前失效的主要原因。采用改进后的旋翼桨叶完成另外两件疲劳试验。依据有限元分析计算出应力集中系数,结合第一件试验结果得到的疲劳极限与第二件、第三件疲劳试验的疲劳极限基本吻合。从试验、计算两方面均证明结构应力集中是疲劳试验提前失效主要原因。
A helicopter rotor blade fatigue test occurred in the skin fracture, life expectancy well below the design requirements. The analysis shows that the quality of skin molding, foam on the skin of the seam less affected, enough to cause blade fatigue test early failure. Finite element simulation found that the thickness of the skin caused by uneven stress concentration is the main reason for early fatigue failure test. Two additional fatigue tests were performed with the modified rotor blade. According to the finite element analysis to calculate the stress concentration factor, combined with the first test results obtained fatigue limit and the second and third fatigue test fatigue limit is basically consistent. From the experiment and the calculation, it is proved that the structural stress concentration is the main cause of the fatigue failure in advance.