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  本文選題：無損檢測 + 脈沖渦流　； 參考：《浙江大學》2015年碩士論文

【摘要】：多層導電結構在國民經(jīng)濟中應用廣泛,并且隨著重要裝備安全監(jiān)測與保障要求不斷提高,提高其無損檢測系統(tǒng)的可靠性變得至關重要。脈沖渦流檢測技術是一種較新的電磁無損檢測技術,對多層結構的檢測有很好的效果。本文結合國家自然科學基金項目,圍繞多層導電結構內層缺陷的在線檢測、脈沖渦流瞬態(tài)響應信號的處理、脈沖渦流掃描成像技術以及原型系統(tǒng)的研發(fā)進行了理論與實驗的研究,增強了對多層結構內層缺陷的檢測能力。本文的主要工作和創(chuàng)新點如下：1)研究了脈沖渦流檢測方法的基本原理,利用建立檢測系統(tǒng)的電路模型,推導了脈沖渦流時域響應信號的表達式,并進行了有限元仿真的研究,闡述分析了脈沖渦流檢測系統(tǒng)的可行性,為檢測系統(tǒng)開發(fā)奠定了理論依據(jù)。2)在現(xiàn)有的脈沖渦流信號分析研究的基礎上,提出一種基于Fisher線性判別的缺陷自動參數(shù)識別的方法。通過Fisher線性判別對脈沖渦流的瞬態(tài)響應信號進行特征提取,然后利用支持向量機算法,進行自動缺陷定位與缺陷類型識別,提高缺陷參數(shù)識別的可靠性。3)采用脈沖渦流掃描成像技術,提出了一種基于Canny算子的缺陷邊緣檢測方法。在得到脈沖渦流掃描成像圖后,采用所提出的方法,提取出圖像的邊緣,根據(jù)邊緣信息對缺陷的位置等信息進行定量化的評估。并結合第2點中提出的缺陷自動參數(shù)識別方法,提出了一種缺陷在線自動評估方法。4)針對多層導電結構,在脈沖渦流檢測機理的基礎上,設計了脈沖渦流C掃描檢測原型系統(tǒng),對硬件和軟件設計進行了改進。綜合實驗結果表明,應用脈沖渦流檢測方法,可實現(xiàn)多層導電結構缺陷的識別與評估,增強了檢測系統(tǒng)的可靠性,為重要裝備的無損檢測與評估提供了技術支持。
[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.
【學位授予單位】：浙江大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TB302.5

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本文編號：1793654