本文選題：旋轉(zhuǎn)機(jī)械　切入點(diǎn)：非平穩(wěn)信號　出處：《北京交通大學(xué)》2012年碩士論文　論文類型：學(xué)位論文

【摘要】：旋轉(zhuǎn)機(jī)械故障診斷的一個重要內(nèi)容是對間歇性非平穩(wěn)故障的檢測與分析。階比分析是一種針對旋轉(zhuǎn)機(jī)械非平穩(wěn)振動信號的變頻采樣分析技術(shù),分為硬件階比分析與時(shí)-頻階比分析。時(shí)-頻階比分析無需特定復(fù)雜的硬件設(shè)備,克服了傳統(tǒng)階比分析價(jià)格昂貴和安裝不便的問題。但是硬件的缺失與軟件算法對時(shí)一頻階比分析產(chǎn)生了一定限制,使得其分析精度與速度目前與傳統(tǒng)硬件階比分析仍然存在較大的差距。 本文在對旋轉(zhuǎn)機(jī)械典型故障特征、振動信號的測量、非平穩(wěn)信號的時(shí)頻分析和傳統(tǒng)階比分析方法進(jìn)行詳細(xì)介紹的基礎(chǔ)上,對新興的非平穩(wěn)旋轉(zhuǎn)機(jī)械故障診斷方法時(shí)-頻階比分析的實(shí)現(xiàn)過程及其軟件算法精度的提高進(jìn)行研究。針對其中的關(guān)鍵問題如瞬時(shí)頻率估計(jì)、峰值搜索、轉(zhuǎn)速曲線擬合及奇異點(diǎn)平滑處理等進(jìn)行改進(jìn)。另外,將改進(jìn)后的時(shí)-頻階比分析與Gabor展開算法相結(jié)合,實(shí)現(xiàn)了復(fù)雜機(jī)械振動信號中特定階比分量的提取及其時(shí)域波的形近似重構(gòu)。 改進(jìn)瞬時(shí)頻率估計(jì)方法,將現(xiàn)代時(shí)頻分析方法Wigner-Ville分布與短時(shí)傅里葉變換進(jìn)行對比分析,研究利用Wigner-Ville提高時(shí)-頻階比分析的瞬時(shí)頻率估計(jì)精度。針對多分量振動信號Wigner-Ville分析過程中產(chǎn)生的交叉干擾項(xiàng),采用同時(shí)在時(shí)間軸和頻率軸加窗的方式進(jìn)行平滑處理,減小干擾項(xiàng)“偽峰值”對瞬時(shí)頻率估計(jì)的干擾。 采用一種改進(jìn)的三次樣條多項(xiàng)式擬合法對轉(zhuǎn)速曲線進(jìn)行擬合,同時(shí)采用一階差分法對擬合過程中出現(xiàn)的奇異點(diǎn)進(jìn)行平滑處理,提高轉(zhuǎn)速曲線擬合精度,改善非平穩(wěn)信號的頻譜分析中存在的“頻譜模糊”現(xiàn)象,提高了階比譜的分辨率。 利用Gabor變換算法的可逆性,將之與改進(jìn)的時(shí)-頻階比分析算法相結(jié)合,在時(shí)頻域內(nèi)提取復(fù)雜機(jī)械振動信號中的特定階比分量,并對其時(shí)域波形進(jìn)行近似重構(gòu),實(shí)現(xiàn)了基于正交離散Gabor展開的時(shí)變帶通階比濾波,克服了傳統(tǒng)階比分析無法在時(shí)域內(nèi)提取階比分量的不足。 最后,利用ST-5000A型多功能柔性轉(zhuǎn)子試驗(yàn)臺試驗(yàn)系統(tǒng)進(jìn)行旋轉(zhuǎn)實(shí)驗(yàn),驗(yàn)證本文方法的正確性和有效性。
[Abstract]:The detection and analysis of intermittent non-stationary faults is an important part of rotating machinery fault diagnosis. Order ratio analysis is a frequency conversion sampling analysis technique for non-stationary vibration signals of rotating machinery. It is divided into hardware order analysis and time-frequency order analysis. It overcomes the problems of expensive and inconvenient installation of traditional order analysis, but the lack of hardware and software algorithm have some limitations on time-frequency ratio analysis. So there is still a big gap between the precision and speed of the analysis and the traditional hardware order analysis. In this paper, the typical fault characteristics of rotating machinery, the measurement of vibration signals, the time-frequency analysis of non-stationary signals and the traditional methods of order analysis are introduced in detail. In this paper, the implementation process of time-frequency ratio analysis and the improvement of the accuracy of software algorithm for fault diagnosis of non-stationary rotating machinery are studied. The key problems such as instantaneous frequency estimation, peak value searching, and so on, are discussed. The speed curve fitting and singular point smoothing are improved. In addition, the improved time-frequency order analysis is combined with the Gabor expansion algorithm. The extraction of specific order component from complex mechanical vibration signal and the shape approximate reconstruction of time-domain wave are realized. The method of instantaneous frequency estimation is improved, and the Wigner-Ville distribution of modern time-frequency analysis method is compared with that of short-time Fourier transform. In order to improve the instantaneous frequency estimation accuracy of time-frequency ratio analysis, Wigner-Ville is used to improve the instantaneous frequency estimation accuracy. In view of the cross-interference in the process of Wigner-Ville analysis of multi-component vibration signals, a smoothing method is adopted, in which both the time axis and the frequency axis are windowed at the same time. Reduce the interference of the interference term "pseudo peak" to the instantaneous frequency estimation. An improved cubic spline polynomial fitting method is used to fit the rotational speed curve and the first order difference method is used to smooth the singular points in the fitting process to improve the fitting accuracy of the rotational speed curve. In order to improve the resolution of order spectrum, the phenomenon of "spectral ambiguity" in spectrum analysis of non-stationary signals is improved. By using the reversibility of the Gabor transform algorithm and the improved time-frequency order analysis algorithm, the specific order components of the complex mechanical vibration signal are extracted in the time-frequency domain, and the time-domain waveform is approximately reconstructed. The time-varying band-pass ratio filtering based on orthogonal discrete Gabor expansion is realized, which overcomes the shortage of traditional order analysis which can not extract order components in time domain. Finally, the ST-5000A multi-functional flexible rotor test system is used to carry out rotation experiments to verify the correctness and effectiveness of the proposed method.
【學(xué)位授予單位】：北京交通大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2012
【分類號】：TH165.3

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