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.

功能分级热障涂层 (FGC) 用于能源生产工程和飞机应用中燃气轮机发动机最热部件，可保护内部金属部件免遭过热和熔化。提高这些发动机的容量需要提高工作温度，而这依赖于FGC在提高温度耐久性和抗断裂性方面的进一步改进。在制造和使用过程中，FGC 中会出现一些小缺陷，然后这些缺陷就会引发裂纹；缺陷和裂纹会改变 FGC 的导热性和断裂强度。在此背景下，迫切需要研究高热通量影响下均质基底上的功能梯度涂层（FGC/H）的热断裂。该项目的主要目标是开发计算半解析模型在热和机械载荷下，对均匀基材 FGC/H（涂层和基材之间由于氧化过程而形成的附加氧化层）上的功能梯度涂层进行断裂分析。随着温度升高和高热通量而出现的许多新问题将得到解决，例如 FGC/H 与预先存在的相互作用裂纹系统的导热问题；由于裂缝内气体的导热性，裂缝将被视为部分导热。材料属性随温度变化很大，这将在模型中得到考虑。 FGC 的热性能和弹性性能将从实际应用的角度对 FGC 在热载荷和机械载荷下裂纹的具体问题进行建模。热问题和热弹性（塑性）问题将通过积分方程来表达。将使用积分的特殊求积公式以数值方式获得解。此外，对于一些特殊情况，例如，将获得新的近似解析解。用于热渗透裂缝的相互作用。这种半解析方法可以将结构材料参数（材料级配、裂纹参数）和热机械载荷参数与主要断裂特征相关联。该模型与详细的参数分析相结合，有助于优化 FGC 的级配及其结构，从而提高在高温下运行的 FGC/H 系统的抗断裂性。在这方面，我们将分析 FGC 潜在所需的热性能和机械性能，以及用于先进热障涂层应用的可用真实材料组合。