本文關(guān)鍵詞： 無損檢測 電磁聲發(fā)射 時(shí)頻分析 經(jīng)驗(yàn)?zāi)B(tài)分解 希爾伯特黃變換　出處：《重慶三峽學(xué)院》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：電磁聲發(fā)射(Electromagnetically Acoustic Emission,EMA)技術(shù)是一種新型的無損檢測技術(shù),憑借其檢測方式簡單,具有重大的應(yīng)用價(jià)值。通過設(shè)計(jì)實(shí)驗(yàn)系統(tǒng),采用了新的電磁加載方式,實(shí)現(xiàn)更加穩(wěn)定可靠的非接觸式電磁加載方案,激勵(lì)產(chǎn)生聲發(fā)射信號。由于聲發(fā)射信號的非線性,非平穩(wěn)特點(diǎn),針對性的采用時(shí)頻分析技術(shù)對信號進(jìn)行分析,從而得到了缺陷信號的時(shí)頻特征。主要研究工作如下:(1)電磁加載激發(fā)聲發(fā)射信號的核心步驟是對有缺陷的金屬試樣施加電磁加載,因此穩(wěn)定的電磁加載尤為重要。建立了穩(wěn)定高效的電磁加載實(shí)驗(yàn)平臺,將核心電磁加載器件CH130電磁鐵、MAN-10030電流源和SAEU2S聲發(fā)射系統(tǒng)有機(jī)結(jié)合,實(shí)現(xiàn)了對有無缺陷試樣,不同材料試樣的非接觸式電磁加載,并成功采集到電磁聲發(fā)射信號。(2)針對電磁聲發(fā)射信號,采用多種時(shí)頻分析法,分析信號的時(shí)頻特性表現(xiàn),綜合對比研究了維格-納威利分布,偽維格-納威利分布,平滑偽維格-納威利分布和小波變換時(shí)頻分析技術(shù),從時(shí)頻聚集角度,交叉項(xiàng)干擾,時(shí)頻分辨率,初動(dòng)點(diǎn),聲發(fā)射能量釋放等多角度深入探討了缺陷電磁聲發(fā)射信號的不同特征。(3)對時(shí)頻分析技術(shù)進(jìn)一步探究,采用希爾伯特黃變換,從電磁聲發(fā)射信號本身出發(fā),將復(fù)雜信號分解為擁有固定模式的不同的本征模態(tài)函數(shù),反應(yīng)了電磁聲發(fā)射信號的階段性,分析了每一階段的頻率,幅值,能量等重要參數(shù)變化特性。(4)通過經(jīng)驗(yàn)?zāi)B(tài)分解算法,從復(fù)雜的非線性、非平穩(wěn)信號中提取出奇異點(diǎn),能量釋放時(shí)間,持續(xù)時(shí)間等關(guān)鍵的物理變量,并通過信號分量包絡(luò)譜和瞬時(shí)頻率的變化闡述原信號重要特征。
[Abstract]:Electromagnetic acoustic emission (Acoustic) technique is a new nondestructive testing technique. With its simple detection method, it has great application value. By designing the experimental system, a new electromagnetic loading method is adopted to realize a more stable and reliable non-contact electromagnetic loading scheme. Acoustic emission signals are generated by excitation. Due to the nonlinear and non-stationary characteristics of acoustic emission signals, time-frequency analysis technology is used to analyze the signals. The main research work is as follows: 1) the core step of the electromagnetic loading excitation acoustic emission signal is to apply electromagnetic loading to the defective metal sample. Therefore, stable electromagnetic loading is particularly important. A stable and efficient electromagnetic loading experimental platform is established, and the core electromagnetic loading device CH130 electromagnet is put forward. The MAN-10030 current source and the SAEU2S acoustic emission system are combined to realize the non-contact electromagnetic loading on the samples with or without defects and the samples of different materials. The electromagnetic acoustic emission (EAE) signal is successfully collected. (2) aiming at the electromagnetic acoustic emission signal, various time-frequency analysis methods are used to analyze the time-frequency characteristic of the signal, and a comprehensive comparative study of the Weig-Navelli distribution is made. Pseudo-VG-Navilli distribution smoothing pseudo-VG-Neville distribution and wavelet transform time-frequency analysis technology from the angle of time-frequency clustering cross-term interference time-frequency resolution initial point. The different characteristics of electromagnetic acoustic emission (EAE) signals with defects are discussed in detail. The time-frequency analysis technology is further explored. The Hilbert-Huang transform is used to start from the electromagnetic acoustic emission signal itself. The complex signal is decomposed into different intrinsic mode functions with fixed mode, which reflects the phase of electromagnetic acoustic emission signal, and analyzes the frequency and amplitude of each stage. The key physical variables such as singularity, energy release time, duration and so on are extracted from complex nonlinear and non-stationary signals by empirical mode decomposition (EMD) algorithm. The important characteristics of the original signal are explained by the variation of the envelope spectrum and the instantaneous frequency of the signal.
【學(xué)位授予單位】：重慶三峽學(xué)院
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：O441

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