【摘要】：無損檢測是保障重大工程裝備制造質(zhì)量和運行安全的關(guān)鍵技術(shù)。多層材料由于其特殊的結(jié)構(gòu)和性能在核工業(yè)、航空航天等關(guān)鍵領(lǐng)域中得到了廣泛的應(yīng)用,保障這些關(guān)鍵部件的質(zhì)量至關(guān)重要。多層材料由于其復(fù)雜的結(jié)構(gòu)、通常具有的厚度、材料屬性的多樣性以及實際檢測環(huán)境的限制,對大多數(shù)無損檢測技術(shù)提出了挑戰(zhàn)。電磁無損檢測技術(shù)是通過電磁感應(yīng)原理來檢測被測件中的損傷和不連續(xù),具有快速、非接觸、不需耦合劑以及非破壞性等優(yōu)點,本論文主要通過兩種先進的電磁無損檢測技術(shù),渦流熱成像和遠場渦流無損檢測技術(shù),分別對碳纖維復(fù)合材料中的沖擊損傷和多層異種金屬粘接結(jié)構(gòu)中的粘接缺陷檢測問題進行了系統(tǒng)地對比研究。分析兩種先進電磁無損檢測技術(shù)對多層結(jié)構(gòu)質(zhì)量檢測各自的優(yōu)缺點。本文的主要研究內(nèi)容如下:1)渦流脈沖熱成像中缺陷及物理特征的多維挖掘。渦流脈沖熱成像是一種新興的電磁無損檢測技術(shù),在獲取熱像視頻后,目前通常的方法是通過從中人為選取一幀圖像進行缺陷的檢測和評估,這種人為幀圖的主觀選擇不可避免地對檢測結(jié)果造成影響。本論文通過基于能量的小波分析方法,對熱成像檢測信號在空間-時間-頻等多維域進行數(shù)據(jù)挖掘分析,提出了渦流熱成像檢測中自動選取幀圖像和缺陷特征提取的方法。2)碳纖維復(fù)合材料中微弱沖擊損傷的檢測。對帶有沖擊損傷的碳纖維復(fù)合材料層壓板在反射模式下進行體積型感應(yīng)加熱,用熱像儀記錄整個加熱階段和冷卻階段試件表面的熱響應(yīng)。得到檢測熱像圖序列后,使用小波分析工具對熱像視頻進行分析,通過一些標準選擇最佳的觀測尺度和最優(yōu)母小波函數(shù),最終成功將熱像圖中的纖維編織信息和沖擊損傷信息分離開來,并成功檢測到位于低頻成分中的沖擊損傷。3)研究了渦流熱成像和遠場渦流兩種無損檢測技術(shù)對多層異種金屬粘接結(jié)構(gòu)粘接質(zhì)量的檢測性能。渦流熱成像在反射模式下受到趨膚效應(yīng)的限制只能檢測到表面缺陷,在透射模式下單次脈沖產(chǎn)生的熱量無法透過試件,多次脈沖激勵的方式可以解決熱量無法穿透試件的問題,但同時受到橫向熱擴散使缺陷信息變得模糊。遠場渦流可以有效檢測到兩層鉛鋼粘接結(jié)構(gòu)內(nèi)部缺陷,對四層鉛鋼粘接結(jié)構(gòu)內(nèi)部缺陷檢測仍然存在困難。未來需要展開針對四層鉛鋼粘接結(jié)構(gòu)的傳感器設(shè)計,并且配合X-Y工作臺實現(xiàn)對多層異種金屬粘接結(jié)構(gòu)更精確的檢測。
[Abstract]:Nondestructive testing is the key technology to ensure the manufacturing quality and operation safety of major engineering equipment. Because of its special structure and properties, multi-layer materials have been widely used in nuclear industry, aerospace and other key fields, so it is very important to ensure the quality of these key components. Multi-layer materials challenge most nondestructive testing technologies because of their complex structure, thickness, diversity of material properties and limitations of the actual testing environment. Electromagnetic nondestructive testing technology is based on the principle of electromagnetic induction to detect the damage and discontinuity in the tested parts, which has the advantages of fast, non-contact, no coupling agent and non-destructive. In this paper, two advanced electromagnetic nondestructive testing technologies, vortex thermal imaging and far-field eddy current nondestructive testing technology, are mainly adopted. The impact damage in carbon fiber composites and the detection of bonding defects in multi-layer dissimilar metal bonding structures were systematically compared and studied. The advantages and disadvantages of two advanced electromagnetic nondestructive testing techniques for multi-layer structure quality testing are analyzed. The main contents of this paper are as follows: 1) Multidimensional mining of defects and physical characteristics in vortex pulse thermal imaging. Eddy current pulse thermal imaging is a new electromagnetic nondestructive testing technology. After obtaining the thermal image video, the common method is to detect and evaluate the defects by artificially selecting a frame image from the middle. The subjective selection of this artificial frame graph inevitably affects the detection results. In this paper, the data mining of thermal imaging detection signal in multi-dimensional domain such as space-time-frequency is carried out by wavelet analysis method based on energy, and a method of automatic selection of frame image and defect feature extraction in Eddy current thermal imaging detection is proposed. 2) the detection of weak impact damage in carbon fiber composites. The volume induction heating of carbon fiber composite laminates with impact damage was carried out in reflection mode. The thermal responses of the whole heating stage and cooling stage were recorded by thermal imager. After the thermal image sequence is detected, the thermal image video is analyzed by wavelet analysis tool, and the optimal observation scale and optimal parent wavelet function are selected through some standards. finally, the fiber weaving information and impact damage information in the thermal image are separated successfully. The impact damage in low frequency composition was successfully detected. 3) the bonding properties of multi-layer dissimilar metal bonding structure were studied by vortex thermal imaging and far-field eddy current nondestructive testing. Eddy current thermal imaging can only detect surface defects under the limitation of skin effect in reflection mode, and the heat generated by a single pulse can not pass through the specimen in transmission mode. The problem that heat can not penetrate the specimen can be solved by multiple pulse excitation, but at the same time, the defect information becomes blurred by transverse thermal diffusion. The internal defects of two-layer lead-steel bonding structure can be effectively detected by far-field eddy current, but it is still difficult to detect the internal defects of four-layer lead-steel bonding structure. In the future, the sensor design for four-layer lead steel bonding structure needs to be carried out, and the multi-layer dissimilar metal bonding structure can be detected more accurately with X / Y worktable.
【學位授予單位】：電子科技大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TB302.5

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相關(guān)期刊論文 前1條

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本文編號：2504731