带热障涂层气冷叶片孔边局部应力分析

Analysis of local stress at hole edge of air-cooled blade with thermal barrier coatings

基于有限元法计算了热障涂层-基体系统热失配状态下的孔边应力,计算结果表明:涂层界面法向应力和界面切应力集中于孔边,孔边周向正应力较大,孔边涂层容易出现开裂和剥落。计算并分析了陶瓷层厚度、计算模型外径、氧化层厚度、孔径和温度分布对孔边局部应力的影响,结果表明:界面法向应力和界面切应力的作用范围随陶瓷层厚度的增加而增大,叶片冷却孔边应力计算子模型外径应大于4倍陶瓷层厚度与1/2孔径之和;冷却状态下,氧化层厚度的增加会增大界面法向正应力和界面切应力;高温下,孔径越小孔边陶瓷层周向正应力越大;在孔边温度非均匀分布的情况下界面应力和孔边周向正应力会增大。

The stress distributions of the thermal barrier coating-substrate system with a hole under thermal mismatch were calculated using finite element method.Calculation results indicated that the interfacial normal/shear stress concentration occurred at the edge of the film hole,and higher circumferential stress existed near the edge of the hole.The coating near the hole edge was prone to cracking and spalling.The effects of the thickness of the ceramic layer,the outer diameter of the model,the thickness of the oxide layer,the hole diameter,and the temperature distribution on the local stress near the hole edge were calculated and analyzed.Results revealed that the region with interfacial normal and shear stress became larger while the thickness of the ceramic layer increased.The outer diameter of the sub-model,which was used to calculate the stress near the edge of the film hole,should be greater than the sum of four times of the ceramic layer’s thickness plus half of the diameter of the hole.Under the cooling condition,the interfacial normal and shear stress increased with the thickness of the oxide layer.At high temperature,the circumferential stress at the edge of the ceramic layer near the hole decreased with the diameter of the hole.The interfacial stress and circumferential stress near the hole edge increased in the case of non-uniform temperature distribution.