论文部分内容阅读
为了建立CMC疲劳寿命预测方法,推广CMC在航空发动机中的应用,根据BHE剪滞模型理论,分析了随着疲劳峰值应力的大小不同,CMC可能出现的4种疲劳迟滞行为,推导了每种迟滞行为下的循环应力-应变公式,模拟了给定应力条件下的疲劳迟滞回线,通过与试验数据对比,证明了迟滞回线模拟的准确性,进一步分析了界面剪应力随疲劳循环数的退化关系。结合界面剪应力退化模型与纤维强度退化模型,设计了纤维应力计算和疲劳寿命计算流程。针对2维编织CMC,根据单胞有限元计算结果提取了纤维束应力,并对CMC进行了疲劳寿命计算,推导了CMC疲劳寿命S-N曲线,其结果与试验数据基本吻合。针对2维编织CMC的疲劳寿命预测方法,可用于编织结构的CMC涡轮导叶疲劳寿命分析。
In order to establish CMC fatigue life prediction method and promote the application of CMC in aeroengine, according to the theory of BHE shear lag model, four kinds of fatigue hysteresis behaviors that CMC may appear along with the different peak fatigue stress are deduced. Behavior of the cyclic stress - strain formula to simulate a given stress fatigue hysteresis loop, compared with the test data to prove the hysteresis loop simulation accuracy, and further analysis of the interface shear stress with fatigue cycle number of degradation relationship. Combined with the interface shear stress degradation model and the fiber strength degradation model, the fiber stress calculation and the fatigue life calculation flow were designed. For 2-D braided CMC, the stress of fiber bundle was extracted based on the results of single-cell finite element calculation. The fatigue life of CMC was calculated and the S-N curve of CMC fatigue life was deduced. The results are in good agreement with the experimental data. Fatigue life prediction method for 2-dimensional braided CMC can be used to analyze the fatigue life of CMC turbine guide vanes with braided structure.