The behavior of composite rings against fatigue loading is analyzed. Experimental study is performed to evaluate the ultimate hoop strength of the composite ring as a requirement before fatigue testing. Then, fatigue tests are performed at three different load levels. Afterward, progressive damage modeling in the context of continuum damage mechanics is utilized to theoretically estimate fatigue lifetimes of the investigated rings. The modeling consists of three parts as stress analysis, damage estimation and degradation of mechanical properties. It is mainly aimed to reduce the required runtime for the accomplishment of fatigue analysis while the accuracy is at least compromised. Therefore, a manual technique is adapted for extracting stress components on the ring. Degradation of mechanical properties takes place either through gradual procedure or sets of sudden laws. The gradual degradation of mechanical properties is performed based on the damage progression as a function of cycle numbers and stress state. Sudden degradation is done after occurrence of failure. After reduction of mechanical properties, the model is updated and whole procedure repeats till the whole layers fail. Finally, the results of fatigue modeling are compared with performed experimental study and a very good agreement is observed.

中文翻译：

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复合环的疲劳分析：实验和理论研究

分析了复合环抵抗疲劳载荷的行为。进行实验研究以评估复合环的极限环箍强度，作为疲劳测试前的要求。然后，在三个不同的负载水平下进行疲劳测试。然后，利用连续损伤力学背景下的渐进式损伤建模从理论上估计所研究环的疲劳寿命。建模由应力分析、损伤估计和力学性能退化三部分组成。它的主要目的是减少完成疲劳分析所需的运行时间，同时至少会降低准确性。因此，手动技术适用于提取环上的应力分量。机械性能的退化是通过渐进的过程或突然的规律发生的。机械性能的逐渐退化是基于作为循环次数和应力状态的函数的损伤进展进行的。发生故障后突然退化。降低力学性能后，更新模型并重复整个过程，直到整个层失效。最后，将疲劳建模的结果与进行的实验研究进行比较，观察到非常好的一致性。更新模型并重复整个过程，直到整个层都失败。最后，将疲劳建模的结果与进行的实验研究进行比较，观察到非常好的一致性。更新模型并重复整个过程，直到整个层都失败。最后，将疲劳建模的结果与进行的实验研究进行比较，观察到非常好的一致性。