本文選題：結(jié)構(gòu)健康監(jiān)測　切入點(diǎn)：時頻分析　出處：《電子科技大學(xué)》2014年碩士論文

【摘要】：作為一種有效的實(shí)時在線檢測方法,基于Lamb波的結(jié)構(gòu)健康監(jiān)測技術(shù)成為最近十余年國內(nèi)外的研究熱點(diǎn)。該技術(shù)通過分析嵌入或附著在待測結(jié)構(gòu)上的傳感器所發(fā)送的數(shù)據(jù),實(shí)時地監(jiān)測結(jié)構(gòu)的整體狀況,及時對結(jié)構(gòu)的損傷位置和程度進(jìn)行分析和診斷,在航空航天、大型土木結(jié)構(gòu)等領(lǐng)域具有廣泛的應(yīng)用前景。本文研究薄板中的Lamb波理論,結(jié)合HHT等時頻分析技術(shù)對鋁合金結(jié)構(gòu)進(jìn)行損傷檢測。具體的研究工作如下:首先,從理論上研究Lamb波的傳播特性,通過數(shù)值法求解頻散方程,并繪制出Lamb波的頻散曲線和振動幅度,為有效利用Lamb波進(jìn)行結(jié)構(gòu)損傷檢測提供理論依據(jù)。在此基礎(chǔ)上結(jié)合實(shí)驗(yàn),從中心頻率、波峰數(shù)以及激勵形式等幾個方面對Lamb波激勵信號進(jìn)行優(yōu)化分析。其次,對整個Lamb波損傷檢測系統(tǒng)進(jìn)行了設(shè)計(jì),包括系統(tǒng)的硬件組成以及部分軟件操作。鑒于時域上分析Lamb波信號存在一定的局限性,本文引入HHT、波包分解等信號處理技術(shù),結(jié)合頻域分析,提取信號中的損傷特征信息。通過信號預(yù)處理以及小波多尺度分解對檢測信號進(jìn)行濾波去噪,結(jié)合實(shí)例分析進(jìn)一步論證HHT以及波包分解技術(shù)處理檢測信號的有效性。最后,搭建了基于Lamb波的結(jié)構(gòu)損傷檢測實(shí)驗(yàn)平臺,對鋁合金結(jié)構(gòu)進(jìn)行損傷識別分析以及初步的損傷定位研究。以1mm厚的7050鋁合金板為檢測對象,獲取Lamb波在完好無損、存在裂紋損傷以及圓孔缺陷的板材結(jié)構(gòu)中傳播時的響應(yīng)信號。實(shí)驗(yàn)中通過快速傅立葉變換提取出信號基波和二次諧波的能量以判定損傷是否存在;使用希爾伯特-黃變換提取出信號的最大能量幅值,將其作為表征損傷的特征參數(shù),估計(jì)損傷程度;采用橢圓定位原理,通過希爾伯特-黃變換、波包分解技術(shù)獲取信號能量峰值的到達(dá)時刻,實(shí)現(xiàn)鋁合金結(jié)構(gòu)損傷的初步定位。實(shí)驗(yàn)分析結(jié)果表明,所使用的損傷檢測方法能夠識別損傷以及確定損傷的大致位置,取得了明顯的實(shí)驗(yàn)效果。
[Abstract]:As an effective real-time on-line detection method, structural health monitoring technology based on Lamb wave has become a hot research topic in recent ten years at home and abroad.Large-scale civil structures and other fields have a wide range of applications.In this paper, the theory of Lamb wave in thin plate is studied, and the damage detection of aluminum alloy structure is carried out with HHT isotime-frequency analysis technique.The specific research work is as follows: firstly, the propagation characteristics of Lamb wave are studied theoretically, the dispersion equation is solved by numerical method, and the dispersion curve and vibration amplitude of Lamb wave are drawn.It provides a theoretical basis for the effective use of Lamb wave in structural damage detection.On the basis of the experiments, the excitation signal of Lamb wave is optimized and analyzed from several aspects, such as center frequency, peak number and excitation form.Secondly, the whole Lamb wave damage detection system is designed, including the hardware composition of the system and part of the software operation.In view of the limitation of analyzing Lamb wave signal in time domain, this paper introduces signal processing techniques such as HHT, wave packet decomposition, and combines frequency domain analysis to extract damage characteristic information from the signal.Signal preprocessing and wavelet multiscale decomposition are used to filter and Denoise the detection signal, and the effectiveness of HHT and wave packet decomposition technology in processing the detected signal is further demonstrated by the analysis of practical examples.Finally, an experimental platform of structural damage detection based on Lamb wave is set up to identify and analyze the damage of aluminum alloy structure and to study the damage location of aluminum alloy structure.In the experiment, the energy of signal fundamental wave and second harmonic wave is extracted by fast Fourier transform to determine the existence of damage, and the maximum energy amplitude of signal is extracted by Hilbert-Huang transform, which is regarded as the characteristic parameter to characterize the damage.The damage degree is estimated and the arrival time of the peak energy of the signal is obtained by using the Hilbert-Huang transform and wave packet decomposition technique using the elliptical localization principle to realize the initial location of the damage of aluminum alloy structure.The experimental results show that the damage detection method can identify the damage and determine the general location of the damage, and achieve obvious experimental results.
【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】：2014
【分類號】：TG115.28;TN911.6

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本文編號：1728423