Modeling of fracture of functionally graded thermal barrier coatings under high heat fluxes

高热通量下功能梯度热障涂层断裂的建模

• 批准号: 397980451
• 负责人: Professor Dr. Siegfried Schmauder
• 金额: --
• 依托单位: Institut für Materialprüfung, Werkstoffkunde und Festigkeitslehre (IMWF)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/397980451?language=en
• 关键词: Modeling; fracture; functionally; graded; thermal

Functionally graded thermal barrier coatings (FGCs) are used in energy producing engineering and aircraft applications in the hottest parts of gas-turbine engines, and they protect the inner metallic parts from overheating and melting. Increasing the capacity of these engines requires increasing the operating temperature, and this relies on further improvement of FGCs with respect to improvement of temperature durability and fracture resistance. During manufacturing and service small defects appear in FGCs and then the cracks can initiate from these defects; the defects and cracks change both the thermal conductivity and fracture resistance of FGCs. In this context, a study of thermal fracture of functionally graded coatings on a homogeneous substrate (FGC/H) under the influence of high heat fluxes is of great demand.The main goal of the project is to develop a computational semi-analytical model for the fracture analysis of functionally graded coatings on a homogeneous substrate FGC/H (with an additional oxidation layer between the coating and substrate which is formed as a result of oxidation processes) under thermal and mechanical loading. A number of new issues arising with increased temperatures and with high heat fluxes will be addressed, such as, thermal conductivity problems for FGC/H with pre-existing systems of interacting cracks; the cracks will be considered as partially thermal permeable due to the thermo-conductivity of gas inside the cracks. The material properties vary significantly with temperature and this will be accounted for in the model. The thermal and elastic properties of FGCs will be modeled from the point of view of its practical application to the specific problem of cracks in FGCs under thermal and mechanical loadings. The thermal problem and thermo-elastic (plastic) problems will be formulated by means of integral equations. The solution will be obtained numerically, using special quadrature formulae for the integrals. Besides, new approximate analytical solutions will be obtained for some special cases, e.g. for the interaction of thermally permeable cracks. This semi-analytical approach allows to correlate the structural material parameters (material gradation, crack parameters) and the thermo-mechanical loading parameters with the main fracture characteristics. The model in combination with a detailed parametric analysis can help to optimize the gradation of the FGCs and their structure in order to improve the fracture resistance of FGC/H systems operating under elevated temperatures. In this regard, potentially desirable thermal and mechanical properties of FGCs will be analyzed as well as available real material combinations for advanced thermal barrier coating applications.

功能分级的热屏障涂层（FGC）用于生产工程和飞机应用中，在燃气涡轮发动机的最热部分中，它们可以保护内部金属零件免受过热和熔化的过度。增加这些发动机的容量需要升高工作温度，这依赖于FGC的进一步改善，以提高温度耐用性和断裂抗性。在制造和服务期间，小缺陷出现在FGC中，然后从这些缺陷中引发裂缝。缺陷和裂纹改变了FGC的导热率和断裂性。在这种情况下，对高热通量影响在均质串联（FGC/H）上功能分级涂料的热骨折的研究非常强烈。该项目的主要目的是开发一种计算半分析模型，以进行计算的分析，以在功能逐渐逐渐逐步分析的均匀型氧化剂（与同型型号）中（同型均型）相互构建（同型均具有均匀的氧化）（同型）的氧化作用，这是一位均匀的氧化剂（与其他氧化型）相互构建的氧化物（同型均匀的氧化均应均匀的氧化物，这是一位均匀的氧化型氧化。氧化过程）在热和机械载荷下。将解决随着温度升高和高热通量而引起的许多新问题，例如，FGC/H的导热率问题具有相互作用的裂纹系统；由于裂纹内部的气体的热导率，裂纹将被视为部分渗透性。材料特性随温度的变化很大，并且将在模型中考虑到这一点。 FGC的热和弹性性能将从其实际应用的角度建模，以在热和机械负载下FGC中的特定裂纹问题。热问题和热弹性（塑料）问题将通过积分方程式提出。该解决方案将使用特殊的正交公式进行数值获得。此外，在某些特殊情况下，将获得新的近似分析解决方案，例如用于热渗透裂纹的相互作用。这种半分析方法允许将结构材料参数（材料等级，裂纹参数）和热机械加载参数与主要断裂特性相关联。该模型与详细的参数分析结合使用可以帮助优化FGC及其结构的等级，以改善在升高温度下运行的FGC/H系统的断裂抗性。在这方面，将分析FGC的潜在理想的热和机械性能，以及用于晚期热屏障涂料应用的可用实际材料组合。