基于脉冲涡流技术的多层导电结构内层缺陷检测研究

发布时间：2018-04-23 21:17

本文选题：无损检测 + 脉冲涡流　；参考：《浙江大学》2015年硕士论文

【摘要】：多层导电结构在国民经济中应用广泛,并且随着重要装备安全监测与保障要求不断提高,提高其无损检测系统的可靠性变得至关重要。脉冲涡流检测技术是一种较新的电磁无损检测技术,对多层结构的检测有很好的效果。本文结合国家自然科学基金项目,围绕多层导电结构内层缺陷的在线检测、脉冲涡流瞬态响应信号的处理、脉冲涡流扫描成像技术以及原型系统的研发进行了理论与实验的研究,增强了对多层结构内层缺陷的检测能力。本文的主要工作和创新点如下：1)研究了脉冲涡流检测方法的基本原理,利用建立检测系统的电路模型,推导了脉冲涡流时域响应信号的表达式,并进行了有限元仿真的研究,阐述分析了脉冲涡流检测系统的可行性,为检测系统开发奠定了理论依据。2)在现有的脉冲涡流信号分析研究的基础上,提出一种基于Fisher线性判别的缺陷自动参数识别的方法。通过Fisher线性判别对脉冲涡流的瞬态响应信号进行特征提取,然后利用支持向量机算法,进行自动缺陷定位与缺陷类型识别,提高缺陷参数识别的可靠性。3)采用脉冲涡流扫描成像技术,提出了一种基于Canny算子的缺陷边缘检测方法。在得到脉冲涡流扫描成像图后,采用所提出的方法,提取出图像的边缘,根据边缘信息对缺陷的位置等信息进行定量化的评估。并结合第2点中提出的缺陷自动参数识别方法,提出了一种缺陷在线自动评估方法。4)针对多层导电结构,在脉冲涡流检测机理的基础上,设计了脉冲涡流C扫描检测原型系统,对硬件和软件设计进行了改进。综合实验结果表明,应用脉冲涡流检测方法,可实现多层导电结构缺陷的识别与评估,增强了检测系统的可靠性,为重要装备的无损检测与评估提供了技术支持。
[Abstract]:Multilayer conductive structures are widely used in the national economy, and with the increasing requirements of safety monitoring and support for important equipment, it is very important to improve the reliability of the NDT system. Pulsed eddy current testing is a new electromagnetic nondestructive testing technique, which has good effect on multilayer structure detection. Based on the project of National Natural Science Foundation of China, this paper focuses on the on-line detection of inner layer defects of multi-layer conductive structures and the processing of transient response signals of pulse eddy current. The research and development of pulsed eddy current scanning imaging technology and prototype system are carried out in theory and experiment to enhance the detection ability of the inner layer defects of multi-layer structure. The main work and innovation of this paper are as follows: (1) the basic principle of pulsed eddy current detection method is studied, and the expression of time domain response signal of pulse eddy current is deduced by using the circuit model of the detection system, and the finite element simulation is carried out. The feasibility of the pulsed eddy current detection system is analyzed. The theoretical basis for the development of the detection system is established. On the basis of the analysis and research of the existing pulse eddy current signal, a method of automatic defect parameter identification based on Fisher linear discrimination is proposed. The transient response signal of pulse eddy current is extracted by Fisher linear discriminant, then automatic defect location and defect type identification are carried out by using support vector machine (SVM) algorithm. In order to improve the reliability of defect parameter identification, a defect edge detection method based on Canny operator is proposed. After obtaining the image of pulse eddy current scanning, the edge of the image is extracted by the proposed method, and the position of the defect is quantitatively evaluated according to the edge information. Combined with the defect automatic parameter identification method proposed in the second point, a defect on-line automatic evaluation method .4) aiming at the multi-layer conductive structure, based on the mechanism of pulse eddy current detection, the prototype system of pulse eddy current C scan detection is designed. The hardware and software design are improved. The comprehensive experimental results show that the application of pulsed eddy current detection method can realize the identification and evaluation of defects of multi-layer conductive structures, enhance the reliability of the detection system, and provide technical support for nondestructive testing and evaluation of important equipment.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB302.5

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