Analytical modeling and analysis of fracture of functionally graded coatings

功能梯度涂层断裂的分析建模和分析

基本信息

批准号：
242255642
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：
2013
资助国家：
德国
起止时间：
2012-12-31 至 2017-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/242255642?language=en
关键词：
Analytical modeling analysis fracture functionally

项目摘要

Functionally graded coatings (FGCs) are applied in thermal, wear and corrosion barriers which are used in different fields, such as, nuclear energy, aerospace, engineering, etc. They are subjected to different thermal and mechanical loading and have to resist high temperature, wear and aggressive environments. However, cracks can initiate from initial defects or micro-cracks appear during manufacturing or service. Therefore, the study of fracture of FGC structures is important for a better understanding of the fracture resistance of graded coatings. The primary objective of the project is to develop a computational semi-analytical model for the fracture analysis of FG thermal barrier coatings on a homogeneous substrate subjected to thermo-mechanical loading with plasticity incorporated in the model. The problem of fracture of FGC/homogeneous structures (semi-infinite isotropic medium) will be investigated under the influence of thermal and/or mechanical loads (e.g., a heat flux, residual thermal stresses caused by cooling-heating, tension). These problems reflect the most important cases which arise during the exploitation of FGC structures. The problem for FGC structures with pre-existing systems of cracks (edge cracks, interface cracks between the coating and substrate or internal cracks in the FGC) will be formulated in general by means of integral equations and with accounting for plastic zones (in the frame of the Dugdale model) at the cracks. Then, typical crack patterns for FGCs resulting from experiments available in the literature will be studied in detail on the basis of the derived model. The thermal and elastic properties of FGMs will be modeled from the point of view of its applicability to problems of cracks in FGCs under thermal and mechanical loadings. In order to simplify the problem relevant functional forms, such as, exponential or power law functions, will be used to simulate the non-homogeneous properties of FGCs. On the basis of this semi-analytical model the simulation of fracture processes in FGCs will be performed for different real material combinations (ceramic/ceramic, ceramic/metal) and material property variations in the FGC. This simulation will provide knowledge for choosing appropriate material combinations and the gradation profile of FGCs in order to optimize the fracture resistance of the FGCs.

功能梯度涂层（FGC）应用于核能、航空航天、工程等不同领域的热、磨损和腐蚀屏障。它们承受不同的热和机械载荷，并且必须耐高温、磨损和侵蚀性环境。然而，裂纹可能是由初始缺陷或制造或使用过程中出现的微裂纹引起的。因此，FGC结构断裂的研究对于更好地理解梯度涂层的断裂抗力具有重要意义。该项目的主要目标是开发一个计算半解析模型，用于对均匀基材上的 FG 热障涂层进行断裂分析，该基材受到热机械载荷，并且模型中包含塑性。 FGC/均质结构（半无限各向同性介质）的断裂问题将在热和/或机械载荷（例如热通量、冷却-加热引起的残余热应力、张力）的影响下进行研究。这些问题反映了 FGC 结构利用过程中出现的最重要的情况。具有预先存在的裂纹系统（边缘裂纹、涂层和基材之间的界面裂纹或 FGC 中的内部裂纹）的 FGC 结构问题一般将通过积分方程并考虑塑性区域（在框架中）来表述Dugdale 模型）在裂缝处。然后，将在导出模型的基础上详细研究文献中可用的实验产生的 FGC 的典型裂纹模式。 FGM 的热性能和弹性性能将从 FGC 热载荷和机械载荷下裂纹问题的适用性角度进行建模。为了简化问题，将使用相关函数形式（例如指数函数或幂律函数）来模拟 FGC 的非齐次特性。在此半解析模型的基础上，将对 FGC 中不同的实际材料组合（陶瓷/陶瓷、陶瓷/金属）和 FGC 中的材料性能变化进行 FGC 断裂过程的模拟。该模拟将为选择适当的材料组合和 FGC 的级配分布提供知识，以优化 FGC 的断裂阻力。