A finite element analysis code was developed to accurately predict stress and damage fields in thermal barrier coatings (TBCs) systems subjected to thermo-mechanical loadings. An inelastic constitutive equation for TBCs, and a Chaboche-type viscoplastic constitutive equation for Ni-based super alloys (IN738LC) were employed to simulate high-temperature creep and cyclic deformations at a high-temperature condition. Additionally, fatigue crack propagation under thermo-mechanical loadings was performed by eliminating the stiffness matrix ahead of crack tip if the associated damage parameter is larger than the critical value. It was confirmed that stress-strain response and crack initiation/propagation simulated by the developed FE code was matched to the high-temperature tensile test results at all temperature conditions. The thermo-mechanical simulation showed that the crack initiation life in in-phase condition was shorter than one of out-of-phase condition. However, it was revealed that the crack in out-of-phase condition was initiated and propagated along the interface between top and bond coats in TBC multilayered structure, which may overlook the damages occurred in TBC in the gas turbine (GT) inspection service.

开发了有限元分析代码，以准确预测承受热机械载荷的热障涂层（TBC）系统中的应力和损伤场。利用TBC的无弹性本构方程和Ni基超级合金的Chaboche型粘塑性本构方程（IN738LC）来模拟高温条件下的高温蠕变和循环变形。另外，如果相关的损伤参数大于临界值，则通过消除裂纹尖端之前的刚度矩阵来执行在热机械载荷下的疲劳裂纹扩展。可以确认，通过开发的FE代码模拟的应力应变响应和裂纹萌生/扩展与在所有温度条件下的高温拉伸试验结果均匹配。热力学模拟表明，同相条件下的裂纹萌生寿命短于异相条件下的裂纹萌生寿命。然而，揭示了异相状态下的裂纹是在TBC多层结构的顶面和粘结层之间的界面处引发并扩展的，这可能忽略了燃气轮机（GT）检查服务中在TBC中发生的损坏。