热障涂层热疲劳寿命预测模型研究

目的 建立热障涂层寿命预测模型，并研究涂层寿命预测与各种应力应变信息的相关性。方法 首先利用带热障涂层圆管试验结果，将涂层界面简化为余弦曲线，建立了相应的二维轴对称有限元模型；然后根据热障涂层疲劳试验结果，结合线性疲劳累积理论和Manson–Coffin低周疲劳模型，建立了热障涂层的寿命预测模型，并将拟合问题转化为寻优问题，使用遗传算法确定寿命预测模型中的系数；最后基于热障涂层试验的微观照片确定出危险点位置，选取正向、剪切、等效和通过二向应力应变分析方法提取垂直于余弦曲面形貌的11种应力应变信息进行寿命预测，并分析了寿命预测的最大误差和平均误差，对分析的结果进行了验证。结果 采用等效应变范围进行涂层寿命预测的最大误差和平均误差最小，分别为50%和21%，涂层寿命与等效应力的相关性最大。采用等效应变进行寿命预测的结果与文献中的结果相比，最大误差降低了169.1%，整体的寿命预测值从±2倍分散带之内缩小到了±1.5倍分散带之内。采用等效应变范围进行不同工况下的涂层寿命预测，预测结果为130次循环，试验结果为160次循环，寿命预测的结果较好。结论 证明了所建立模型的正确性与准确性，为涂层寿命...

Thermal Fatigue Life Prediction Model for Thermal Barrier Coatings

The work aims to investigate correlation of the thermal barrier coating life prediction model with various stress- strain information. The method used in this paper is as follows. Firstly, referring to experimental results of circular tube with thermal barrier coating, coating interface was simplified to a cosine curve and a corresponding two-dimensional axisymmetric finite element model was established. Then, considering the fatigue experimental results of the thermal barrier coating, the life prediction model of the thermal barrier coating was established by combining linear fatigue accumulation theory and Manson-Coffin equation. And transform fitting problem into an optimization problem, using GA to determine coefficients in the lifetime prediction model. Finally, the location of the risk point is one quarter of the wave peak from the top coat that determined based on microscopic photos of the thermal barrier coating experiment, and life prediction is performed by selecting 11 types stress-strain information that of normal, shear, equivalent and perpendicular to cosine surface morphology by biaxial stress-strain state analysis methods. The maximum error and average error of life prediction are analyzed, and the analysis results are verified. The results show that the maximum and average errors of coating life prediction using the equivalent variation range are minimum, 50% and 21%, respectively. It is also indicated that the coating life has greatest correlation with equivalent stress. The life prediction results of strain range under the maximum principal strain is also accuracy, the maximum error and average error are 52% and 25%, respectively. Compared with the results in the literature, the maximum error of life prediction based on equivalent strain is reduced by 169.1%, and overall life prediction value decreased from within ±2 scattering zone to within ±1.5 scattering zone. The equivalent strain range is used to predict the coating life under different working conditions. The prediction result is 130 cycles and the experimental result is 160 cycles. The above results prove the correctness and superiority of the method used in this paper, and also provide an effective method for predicting the coating life.