等离子喷涂热障涂层中应力分布的有限元模拟

Finite Element Simulation of Stress Distribution in Plasma Sprayed Thermal Barrier Coating

采用热弹性有限元方法研究了热载荷条件下由数值模拟方法生成的热障涂层冷却至室温后的应力分布,分析了热生长氧化物(TGO)层及其厚度对热障涂层应力分布的影响,并与文献的试验结果进行了对比。结果表明:不含TGO层的热障涂层,陶瓷层和粘结层的凸起处为拉应力,凹陷处为压应力;TGO层形成后,陶瓷层凸起处表现为压应力,凹陷处表现为拉应力;界面附近的陶瓷层在TGO层达到一定厚度时出现应力反转现象,且该现象的出现随着界面粗糙度的增大而延迟;模拟预测的应力与文献报道的结果相近,证明了模拟结果的正确性。

A simulated micrograph of thermal barrier coating （TBC） was chosen to study the stress distribution at the thermal loading, cooling from initial temperature to room temperature, by using the thermoelasticity finite element method. The influence of thermally grown oxide （TGO） and its thickness on the stress distribution in TBC were analyzed. The simulated result was compared with the experimental result reported in literature. The results show that tensile stress was present at the peak and compressive stress was present at the valleys in as-sprayed conditions （that is, without TGO）. When growing TGO layer, tensile stress appeard at the valley and compressive stresses appeared at the peak. The stress inversion appeared in the topcoat after reaching a certain TGO thickness, and the stress inversion was delayed by the increase of interface roughness. The predicted values of stress agreed well with the experimental result reported in the literatures, which confirms the validity of the simulation.