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等离子喷涂过程中热障涂层温度与应力的数值模拟

时间:2017-12-06 21:30来源:毕业论文
文在传统结构的热障涂层的基础上提出了新的结构模型,增加了网状结构衬垫,以降低等离子喷涂陶瓷层过程中由于热不匹配及快速冷却带来的残余应力,进而提高热障涂层的服役寿命
摘要本毕业论文在传统结构的热障涂层的基础上提出了新的结构模型,增加了网状结构衬垫,以降低等离子喷涂陶瓷层过程中由于热不匹配及快速冷却带来的残余应力,进而提高热障涂层的服役寿命。为检验网状结构衬垫的作用并且达到优化结构的目的,采用有限元法对等离子喷涂陶瓷层的过程进行了模拟,研究了具有网状结构衬垫的热障涂层内的残余应力分布。首先选取钇稳氧化锆为喷涂材料,建立轴对称模型,通过比较平行于涂层表面方向和垂直于涂层表面方向的应力大小和分布情况,确定最优模型。然后据此模型改变热障陶瓷层与网状结构衬垫宽度的比例,比较应力大小和分布情况,确定最优尺寸参数。结果表明,最优的尺寸是热障陶瓷层与网状结构衬垫宽度比例为5:1,通过将最优尺寸的模型和同尺寸的传统模型比较发现,增加网状结构衬垫改善了残余应力,平行于涂层表面方向的压应力有较大程度的增加,可促使裂纹的愈合,而拉应力大幅减低,降低了裂纹的扩展;涂层边缘处垂直于涂层界面方向的压应力也大幅降低,而这种压应力也是促进垂直表面裂纹形成和扩展的原因之一,因而涂层边缘处垂直于涂层表面方向的压应力减小也提高了涂层的性能。16256
关键词  等离子喷涂 热障涂层 网状结构衬垫 残余应力 有限元法
毕业设计说明书(论文)外文摘要
Title  Numerical simulation of temperature and residual stress field of thermal barrier coating in process of plasma spraying
Abstract
In this paper, a new model of the thermal barrier coating was proposed based on the traditional two-layer model, adding the meshy interlayer to reduce residual stress caused by thermal mismatch and rapid cooling, aimed to increase the service life of thermal barrier coatings. To test the effect of the meshy interlayer and optimize the structure, a finite element method was used to simulate the process of plasma spraying and research the residual stress field of thermal barrier coating with meshy interlayer.  First, the yttria-stabilized zirconia was selected as coating material, and an axisymmetric model was established. The optimal model was selected by comparing the stress field parallel with the coating surface and that vertical to the coating surface. Then the optimal size parameters were determined by changing the width ratio of the ceramic thermal barrier and the meshy interlayer. The results show that the optimal width ratio of the ceramic thermal barrier and meshy interlayer is 5:1. Compared with traditional model with the same size, adding the meshy interlayer has an improvement in terms of stress. In the direction parallel to the surface of the coating, the compressive stress increased, which can promote the healing of the cracks, while the tensile stress was significantly reduced, which can prevent the propagation of the crack; The compressive stress vertical to surface at the edge of coating is also significantly reduced, while this kind of stress is one of the reasons for formation and propagation of vertical cracks, so the decreases of compressive stress vertical to surface can improve the performance of coatings. 源自六;维,论/文.网*加7位QQ324`9114 www.lwfree.cn
Keywords  Plasma spraying Thermal barrier coatings Meshy interlayer
Residual stress Finite element method
 目    次
1  绪论    1
1.1  热障涂层的研究现状    3
1.2  有限元分析方法介绍    7
1.3  等离子喷涂有限元仿真    7
1.4  本文的主要研究内容及意义    9
2  模型    10
2.1  几何模型    10
2.2  材料属性    10
2.3  初始边界条件    11
3  应力分析及结构优化    13 等离子喷涂过程中热障涂层温度与应力的数值模拟:http://www.lwfree.cn/cailiao/20171206/17526.html
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