温度梯度下热障涂层残余应力的解析模型研究

Research on Analytical Model of Residual Stress in Thermal Barrier Coating under Thermal Gradient

热障涂层被广泛应用于航空航天部件,在热载荷作用下材料间所集聚的残余应力是导致其层裂和失效的重要原因。针对热障涂层由于温度梯度产生的热应力不匹配问题,建立了不依赖于材料层数的残余应力分析的解析模型。建立基体-粘结层-陶瓷层的三层平面应变模型,分析了系统内应变、应力的分布情况,研究了温度梯度对层间残余应力的影响。研究了陶瓷层厚度对系统各层表面应力和曲率的影响。结果表明:存在温度梯度时界面处应力有明显的突变,且各层的残余应力比无梯度时的大。表面应力和曲率都随陶瓷层厚度的增加而增加。

The thermal barrier coating is widely used in aerospace components. The residual stress accumulated under thermal load results in the spallation and invalidation between different layers. Based on thermal expansion mismatch of multilayer structures caused by temperature gradients, a generalized residual stress analytical model, in which the solution was independent of the number of layers, was developed. A three-layer plane strain model of substrate-binding layer-ceramic layer was established. The distribution situation of strain and stress in the system was researched. The influences of temperature gradient on the residual stress in the system were researched. The influence of ceramic layer thickness on the surface stress and curvature of each layer was studied. The results show that the stress has obvious abrupt change at the interface when there is temperature gradient, and the residual stress of each layer is larger than that without gradient. The surface stress and curvature increase with the increase of the thickness of the ceramic layer.