本文選題：無損檢測 + 脈沖渦流熱成像　； 參考：《電子科技大學(xué)》2015年碩士論文

【摘要】：無損檢測是保障產(chǎn)品制造質(zhì)量及重大工程設(shè)備可靠運(yùn)行的核心技術(shù)。脈沖渦流熱成像技術(shù)(Eddy Current Plused Thermography,ECPT)作為電磁無損檢測的一種方法,具有非接觸、安全快速、單次測量范圍大等優(yōu)勢,目前已經(jīng)廣泛應(yīng)用于導(dǎo)體材料缺陷的識別和評估,并獲得了豐碩的成果。然而,現(xiàn)有的基于脈沖渦流熱成像技術(shù)的缺陷檢測模型和特征提取方法對微小缺陷,特別是針對尚未形成宏觀微裂紋的隱性缺陷,難以進(jìn)行有效、完整的檢測和評估。并且,僅僅利用簡單圖像處理技術(shù)獲取ECPT缺陷特征而不做深入的物理與數(shù)學(xué)關(guān)系建模將難以真實(shí)描述材料損傷程度變化而導(dǎo)致各類微缺陷的錯誤量化。因此,針對復(fù)雜構(gòu)件缺陷區(qū)域的電磁熱信號特征物理數(shù)學(xué)建模與提取算法的研究具有重大意義。本文旨在利用脈沖渦流熱成像技術(shù)的電、磁、熱等物理效應(yīng),通過理論與實(shí)驗(yàn)相結(jié)合的方法,建立針對復(fù)雜構(gòu)件微弱缺陷檢測的模型(即為熱光流模型);研究并分析所建模型對復(fù)合材料的低沖擊損傷以及齒輪早期疲勞隱形缺陷檢測的通適性。研究內(nèi)容主要有:1)研究缺陷脈沖渦流熱成像檢測機(jī)理,研究熱像儀采樣頻率對缺陷檢測以及材料紋理分析精度的影響,優(yōu)化脈沖渦流熱成像實(shí)驗(yàn)參數(shù);2)分析脈沖渦流熱成像熱傳導(dǎo)機(jī)理,建立熱光流場模型,提出(熱光流)散度以及(熱光流)熵特征提取算法;3)分析熱光流場模型和散度、熵算法對于復(fù)合材料的低沖擊損傷以及齒輪早期疲勞隱形缺陷檢測的靈敏度、準(zhǔn)確性,建立(熱光流)散度/熵特增值與不同缺陷損傷之間的映射關(guān)系,實(shí)現(xiàn)缺陷/損傷的定位分析和定量檢測。研究結(jié)果表明,針對缺陷檢測和辨識,熱像儀存在臨界采樣頻率,當(dāng)采樣頻率控制在臨界數(shù)值時,可實(shí)現(xiàn)對脈沖渦流熱成像無損檢測裝置的參數(shù)優(yōu)化�；诿}沖渦流熱成像機(jī)理建立的熱光流模型具有檢測靈敏度高,物理含義和信息量豐富等優(yōu)點(diǎn),能有效的用于目前存在挑戰(zhàn)的復(fù)合材料低沖擊損傷和金屬材料早期疲勞隱形缺陷的定位檢測和定量分析。本文建立的基于脈沖渦流熱成像機(jī)理的熱光流模型、熱光流-散度算法及熱光流-熵算法,為復(fù)雜構(gòu)件的無損檢測以及全壽命安全評估研究提供了一種新的思想和方法。
[Abstract]:Nondestructive testing (NDT) is the core technology to guarantee the manufacturing quality of products and the reliable operation of major engineering equipment. As a method of electromagnetic nondestructive testing (ENDT), Eddy current used Thermography (ECPT) has the advantages of non-contact, fast safety and large measurement range, so it has been widely used in the identification and evaluation of defects in conductor materials. And has obtained the rich achievement. However, the existing defect detection models and feature extraction methods based on pulsed eddy current thermal imaging are difficult to detect and evaluate microdefects effectively and completely, especially for the hidden defects which have not yet formed macroscopic microcracks. Moreover, it is difficult to describe the damage degree change of materials by using simple image processing technology to obtain ECPT defect features without deep modeling of physical and mathematical relationship, which leads to the error quantization of various microdefects. Therefore, it is of great significance to study the physical mathematical modeling and extraction algorithm of electromagnetic thermal signal features in the defect region of complex components. The purpose of this paper is to utilize the physical effects of electrical, magnetic and thermal effects of pulsed eddy current thermal imaging, and to combine theory with experiment. A model for weak defect detection of complex components (i.e. thermo-optical flow model) is established, and the suitability of the model to the low impact damage of composite materials and the detection of early fatigue invisible defects of gears is studied and analyzed. The main research contents include: (1) study the mechanism of defect pulse eddy current thermal imaging, study the influence of sampling frequency of thermal imager on defect detection and material texture analysis precision. Optimizing the experimental parameters of pulsed eddy current thermal imaging (2) analyzing the thermal conduction mechanism of pulse eddy current thermal imaging, establishing a thermo-optical flow field model, and proposing an algorithm for extracting (thermal optical flow) divergence and entropy feature (3) to analyze the thermal optical flow field model and divergence. The sensitivity and accuracy of entropy algorithm for the detection of low impact damage of composite materials and early fatigue stealth defects of gears are studied. The mapping relationship between the divergence / entropy increment and the damage of different defects is established. The localization analysis and quantitative detection of defect / damage are realized. The results show that the critical sampling frequency exists in the thermal imager for defect detection and identification. When the sampling frequency is controlled at the critical value, the parameters of the pulsed eddy current thermal imaging nondestructive testing device can be optimized. The thermo-optical flow model based on the mechanism of pulsed eddy current thermal imaging has the advantages of high detection sensitivity, rich physical meaning and abundant information. It can be used in the localization and quantitative analysis of low impact damage of composite materials and early fatigue stealth defects of metal materials. The thermo-optical flow model based on the mechanism of pulsed eddy current thermal imaging, the thermo optical flow-divergence algorithm and the thermo-optical flow-entropy algorithm are established in this paper, which provide a new idea and method for the study of nondestructive testing and life safety assessment of complex components.
【學(xué)位授予單位】：電子科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TP391.41;TB302.5

【參考文獻(xiàn)】

相關(guān)期刊論文 前1條

1 耿榮生;景鵬;;蓬勃發(fā)展的我國無損檢測技術(shù)[J];機(jī)械工程學(xué)報;2013年22期

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本文編號：2001514