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.

功能分级的涂层（FGC）用于在不同场中使用的热，磨损和腐蚀屏障，例如核能，航空航天，工程等。它们受到不同的热和机械载荷的约束，必须抵抗高温，磨损和侵略性环境。但是，在制造或服务过程中会出现从初始缺陷或微裂缝中引发的裂缝。因此，FGC结构断裂的研究对于更好地理解分级涂层的断裂性很重要。该项目的主要目的是开发一种计算半分析模型，用于对均匀的基板上的FG热屏障涂层进行断裂分析，该层材料经受了热机械载荷，并在模型中掺入了可塑性。将在热和/或机械负荷的影响下研究FGC/均质结构（半无限型各向同性培养基）断裂的问题（例如，热通量，由冷热加热，张力引起的残留热应力）。这些问题反映了在开发FGC结构期间出现的最重要案例。具有裂纹系统的FGC结构的问题（边缘裂纹，涂料和底物之间的界面裂纹或FGC中的内部裂纹之间的界面裂纹）将通过整体方程以及构成塑料区域（在Dugdale模型的框架中）在裂缝上进行表达。然后，将根据衍生模型详细研究，该模型将详细研究由文献中可用的实验引起的FGC的典型裂纹模式。 FGMS的热和弹性性能将从其适用性的角度建模，用于在热和机械载荷下FGC的裂纹问题。为了简化问题相关的功能形式，例如指数或幂律函数，将用于模拟FGC的非均匀性能。在此半分析模型的基础上，将对FGC中的断裂过程进行模拟，以用于不同的实际材料组合（陶瓷/陶瓷，陶瓷/金属）和FGC中的材料特性变化。该模拟将提供选择适当的材料组合和FGC的渐变谱的知识，以优化FGC的断裂抗性。