民用航空发动机热障涂层结构跨尺度多物理场耦合断裂机理及计算框架研究

跨尺度多物理场耦合疲劳断裂是诸多学科和工程领域中的关键科学问题，物理机理非常复杂，给数值分析带来了严重挑战。扩展逐层方法兼具复合材料逐层理论和扩展有限元方法的优点，易于处理具有层特性的三维裂纹，非常适合于板壳类结构的多物理场耦合断裂问题。本项目拟以航空发动机涡轮叶片热障涂层系统的损伤与断裂问题为背景，发展功能梯度热障涂层结构的跨尺度多场耦合断裂计算框架。首先建立扩展逐层/实体跨尺度分析模型，有效地处理热障涂层与基底结构之间的尺度问题；然后解决现有分析方法在力-热-化-损伤耦合方面的瓶颈问题，实现多物理场的完全耦合求解；最后建立热障涂层中界面和横向裂纹的同时任意扩展预测模型，深入探讨热障涂层中TGO的生长机理和屈曲形态，以及界面和横向裂纹的萌生与扩展机理。本项目的研究成果对具有复杂内部冷却系统的航空发动机结构的分析、设计、优化、使用寿命预测与维修计划制定具有重要理论意义。

Multiscale and multiphysics coupling fatigue fracture problems are of great concern to many disciplines and engineering fields. The physic mechanisms are very complex, which bring serious challenge to the numerical computation. The extended layerwise method (XLWM) possesses the advantages of the Layerwise theory (LW) and extended finite element method (XFEM), so the XLWM can deal with the three-dimensional crack with layer characteristic easily, and it is very suitable for the multiscale and multiphysics coupling damage and fracture problems of the plates/shells structures. For the fatigue fracture problems of thermal barrier coatings (TBCs) system in the turbine fan of aero-engine, a computational framework will be developed in this project, and considering the multiscale and multiphysics coupling of functional gradient TBCs. First of all, the multiscale extended-layerwise/solid-element (XLW/SE) model will be developed for dealing with the disparate length scales effectively. And then, the restrictive obstacle of chemical-thermal-mechanical-damage coupling for existing analysis method will be solved, so the full coupling multiphysics will be achieved. Finally, the predict model for arbitrary growth of the interface and transverse crack will be developed for the TBCs in aero-engine. The grow mechanisms and bending shape of thermal grown oxide (TGO) will be investigated, together with the accurate and reliable criteria for the onset and propagation of transverse and interface cracks as well as their interaction. The research achievements in this project are of great theoretical value for analysis, design, optimization, service life prediction and maintenance planning of the aero-engines turbine with detailed internal cooling system.