基于ECT的航天隔热材料粘接层缺陷检测研究

发布时间：2018-11-01 11:51

【摘要】：随着航天事业的不断发展,热损问题在航天领域越来越引起人们的重视,隔热材料的粘接性能,成为解决热损问题实现航天器安全稳定运行的保证。隔热材料研制工艺的不断发展与创新,在给航天器提供良好的隔热保护的同时也给隔热材料胶接性能检测评估带来了新的要求。因此,本文针对以上问题对基于(Electrical Capacitance Tomography,ECT)的无损检测方法进行了如下研究工作:(1)针对航天隔热材料粘结胶层缺陷检测问题,提出一种基于ECT的隔热材料粘结胶层缺陷无损检测新方法。该方法利用粘结胶层固有介电特性及不同损伤导致介电常数发生改变的物理性质,利用电容重建分布场图像信息的方法进行无损检测。针对航天隔热材料的平面结构特性设计了基于平面电极检测基板的ECT缺陷检测系统。(2)通过分析传统ECT原理及图像重建算法,提出了一种改进初值的Landweber迭代ECT图像重建算法,引入了优化后的迭代初始值,解决了迭代初值偏差问题,进而提升了图像重建质量。(3)针对灵敏度矩阵S会随缺陷场的不同而产生差异,以及常规迭代类成像算法一般都比较依赖初始迭代值的问题,提出一种基于改进粒子群的电容层析成像检测方法。引入了最小二乘支持向量机处理机制,通过最小二乘支持向量机对原始测量电容值进行数据处理,解决了不同缺陷类型分布场的灵敏度矩阵差异造成的误差。然后采用不依赖初始迭代信息的改进的粒子群算法进行图像重建,最后通过实验验证了改进算法的有效性、优越性。
[Abstract]:With the development of aerospace industry, the heat loss problem has attracted more and more attention in the aerospace field. The adhesive property of thermal insulation material has become the guarantee to solve the heat loss problem to realize the safe and stable operation of spacecraft. The continuous development and innovation of thermal insulation materials technology not only provide good thermal insulation protection for spacecraft, but also bring new requirements to the testing and evaluation of the adhesive properties of thermal insulation materials. Therefore, the following research work has been done in this paper: (1) aiming at the defect detection of spaceflight insulating material adhesive layer, A new method based on ECT for nondestructive detection of adhesive defects in insulating materials is proposed. In this method, the intrinsic dielectric properties of the adhesive layer and the physical properties of the dielectric constant caused by different damage are used to perform nondestructive testing using the method of capacitive reconstruction of the distribution field image information. A ECT defect detection system based on plane electrode detection substrate is designed for plane structure characteristics of spaceflight insulation materials. (2) traditional ECT principle and image reconstruction algorithm are analyzed. In this paper, an improved Landweber iterative ECT image reconstruction algorithm with improved initial values is proposed. The optimized initial value is introduced to solve the problem of initial value deviation. Then the image reconstruction quality is improved. (3) for the sensitivity matrix S will be different with the defect field, and the conventional iterative imaging algorithm generally depends on the initial iteration value. An improved particle swarm optimization (PSO) based detection method for electrical capacitance tomography is proposed. The least-squares support vector machine (LS-SVM) is introduced to deal with the data of the original measured capacitance. The error caused by the difference of sensitivity matrix between the different defect types is solved by the least-squares support vector machine (LS-SVM). Then the improved particle swarm optimization (PSO) algorithm, which does not depend on the initial iteration information, is used to reconstruct the image. Finally, the effectiveness and superiority of the improved PSO algorithm are verified by experiments.
【学位授予单位】：燕山大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：V250.2;TP391.41

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