【摘要】：起重機回轉支承工作環(huán)境惡劣，裂紋難以避免。目前，針對旋轉機械發(fā)展較為成熟的振動診斷法對低速重載回轉支承裂紋難以實現有效檢測。裂紋發(fā)生部位通常較為隱蔽，常規(guī)巡檢與在線檢測技術難以有效發(fā)現。針對起重機回轉支承在故障診斷特別是早期故障診斷領域所面臨的難點問題，，本論文通過對早期裂紋形成機理、聲發(fā)射信號傳播規(guī)律及常用材料聲發(fā)射特性進行分析，探討采用聲發(fā)射技術對回轉支承進行裂紋檢測時聲源定位和嚴重程度識別等方面的問題。論文研究內容主要包括： （1）裂紋形成機理及聲發(fā)射檢測可行性分析。利用疲勞接觸理論研究了回轉支承裂紋形成機理及裂紋擴展形式，并在彈性波動理論及聲發(fā)射檢測基本原理的基礎上，分析了利用聲發(fā)射技術對回轉支承裂紋進行檢測的可行性。 （2）聲發(fā)射信號傳播規(guī)律及常用材料聲發(fā)射特性研究。運用顯式算法在ANSYS/LS-DYNA中建立了聲發(fā)射信號傳播模型，研究聲發(fā)射信號在回轉支承套圈中傳播時傳播路徑、動力響應、能量衰減等規(guī)律；利用拉伸試驗和三點彎曲試驗對起重機回轉支承常用材料的聲發(fā)射特性進行了試驗研究。 （3）基于聲發(fā)射技術的裂紋源定位及嚴重程度識別。建立了基于線性時差的回轉支承裂紋源定位方法，采用平滑偽Wigner-Ville分布對閾值時差估計法進行了修正，對定位效果進行了模擬試驗驗證；利用從拉伸試驗全過程中獲取到的聲發(fā)射波形信號，建立了基于小波包能量譜和支持向量機的聲發(fā)射信號嚴重程度識別模型。 （4）回轉支承裂紋檢測試驗研究及工程應用研究。在起重機回轉支承結構健康檢測試驗平臺上進行了回轉支承裂紋檢測試驗研究，驗證了聲發(fā)射檢測在回轉支承裂紋檢測方面的可行性及準確性。在此基礎上開展了起重機回轉支承裂紋檢測的工程應用研究。
[Abstract]:The working environment of the crane slewing support is bad, and the crack is difficult to avoid. At present, it is difficult to detect the crack of low speed heavy load slewing bearing by vibration diagnosis method which is mature for rotating machinery. The location of cracks is usually concealed, and it is difficult to find the conventional inspection and on-line detection techniques. Aiming at the difficult problems of crane slewing bearing in the field of fault diagnosis, especially in the field of early fault diagnosis, this paper analyzes the mechanism of early crack formation, the propagation law of acoustic emission signal and the characteristics of acoustic emission of common materials. In this paper, acoustic emission technology is used to detect the crack of rotary bearing. The problems of sound source location and severity identification are discussed. The main contents of this paper are as follows: (1) the mechanism of crack formation and feasibility analysis of acoustic emission detection. Based on the theory of elastic wave and the basic principle of acoustic emission detection, the mechanism of crack formation and crack propagation in slewing bearing are studied by using fatigue contact theory. The feasibility of using acoustic emission technology to detect cracks in rotary bearing is analyzed. (2) the propagation law of acoustic emission signal and the characteristics of acoustic emission of common materials are studied. The acoustic emission signal propagation model in ANSYS/LS-DYNA is established by using explicit algorithm. The propagation path, dynamic response and energy attenuation of acoustic emission signal propagating in the ring of slewing bearing are studied. The acoustic emission characteristics of the materials commonly used in crane slewing support are studied by tensile test and three-point bending test. (3) crack source location and severity identification based on acoustic emission technology. A method for locating crack source of slewing bearing based on linear time difference is established. The method of threshold time difference estimation is modified by using smooth pseudo-Wigner-Ville distribution, and the localization effect is verified by simulation test. Using the acoustic emission waveform obtained from the whole process of the tensile test, The acoustic emission signal severity recognition model based on wavelet packet energy spectrum and support vector machine is established. (4) the experimental research and engineering application research on crack detection of slewing bearing. The crack detection of slewing bearing is studied on the health test platform of crane slewing bearing structure, and the feasibility and accuracy of acoustic emission detection in the detection of slewing bearing crack are verified. On this basis, the engineering application research of crane slewing bearing crack detection is carried out.
【學位授予單位】：華南理工大學
【學位級別】：碩士
【學位授予年份】：2012
【分類號】：TH165.3

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