TBC界面裂纹K因子的有限元求解方法

The Finite Element Method for Solving K factor of TBC Interfacial Crack

本文针对由陶瓷层和粘结层构成的热障涂层 (TBC)双层材料结构 ,探讨了应用裂纹面位移数据及 J积分计算分析陶瓷层 /粘结层界面裂纹应力强度因子的有限元方法。考虑了拉伸及热应力两种载荷情况。在传热分析时 ,考虑了界面裂纹对传热的影响。对于这类双材料界面裂纹 ,应力强度因子是 型和 型裂纹复合的 ,它包括应力强度因子的模和相位角。根据所得的结果比较 。

Thermal barrier coatings (TBCs) provide thermal insulation to high temperature superalloys.However,the interfacial crack caused by thermal loading at the bond coat/TBC is a fatal factor for TBC spallation and failure.The effects of voids or crack like flaw at the interface can be responsible for initiating debonding and accelerating the oxidation process.The effect of interfacial cracks should be studied by using the fracture mechanics approach.Due to different properties of bond and top coatings,stress intensity factor is complex.The paper presents two methods to evaluate the K factor by using numerical results of finite element method.One utilized crack flank displacement data,and another utilized the J integral.A plate with edge crack under thermal loading and tensile loading is chosen as an example to calculate the stress intensity factors.The variation of the properties as a function of temperature was used for the analysis.Both methods show consistent results,but the J integral method can not obtain the phase angle,whereas the other method uses the crack flank displacement data.The results of the experiments or other numerical methods can also be used for K evaluation.