层合板单钉接头多级疲劳试验

为探讨层合板单钉接头在实际工作中多级疲劳破坏规律,首先通过特征尺寸为层合板端距与螺栓孔孔径之比为3、层合板宽度与螺栓孔孔径之比为3的层合板单钉接头准静态拉伸试验及常幅拉-拉疲劳试验,分析了层合板单钉接头实际损伤失效形式及单级疲劳破坏规律,为其多级疲劳试验各级应力水平的选取提供基础依据.然后对层合板单钉接头在载荷由高到低及由低到高2种加载方式2级载荷作用下的疲劳性能进行了试验研究,并使用经典线性累积损伤理论Miner法则分析计算了接头疲劳损伤值.结果表明:当应力水平由低向高施加时,疲劳损伤值大于1,而应力水平由高向低施加时,疲劳损伤值小于1. 

Experiment on single bolted joints in laminates under multilevel fatigue loading

A series of quasi-static tension experiments and constant amplitude tension-tension fatigue experiments for researching the multilevel fatigue behavior under real cyclic loading were performed on single bolted joints in laminates with the ratio of the width of the laminate to the diameter of the central hole being 3 and the ratio of the distance between the central hole and the end of joint to the diameter of the central hole being 3. Real damage types and failure rules of single bolted joints in laminates were also discussed to provide the basis of stress level selecting of multilevel fatigue experiments.Finally,an experimental program of researching fatigue behavior under two-level fatigue for low-to-high and high-to-low loading sequence was conducted.Fatigue damage index was calculated and analyzed by using the classical linear progressive damage method of Miner rule.The results show that the fatigue damage index is larger than 1 when the loading sequence changes from low-level to high-level.On the contrary,the fatigue damage index is less than 1.