【作者】 伍小燕；

【导师】 陈再良； 朱忠奎；

【作者基本信息】 苏州大学 ， 机械电子工程， 2008， 硕士

【摘要】 随着科学技术和生产的发展,机械设备朝着大型化、高速化、连续化以及结构复杂化的方向发展,一旦设备发生故障就可能引起灾难性的毁坏。因此故障诊断技术日益引起重视,并在理论和实践方面得到迅猛的发展。科学技术的发展,特别是非平稳信号处理技术不断完善,为机械设备故障诊断技术提供了良好的诊断方法。本文主要围绕时频分析方法在滚动轴承故障诊断方面的问题进行了研究。研究短时傅立叶变换、Wigner-ville变换和小波变换的特点,并通过仿真信号验证。在时频分析的基础上提出了一种新的瞬态特征信号的自动检测方法,该方法将小波变换与自动检测方法结合起来检测信号特征,使小波变换系数周期性的叠加在极坐标上,从而达到特征增强和平滑噪声的目的;将该方法应用于滚动轴承故障信号的周期性瞬态特征的检测,有效的检测出了轴承在局部故障引起的瞬态特征。基于小波变换尺度图提出了一种能量系数重置法,将基于小波变换尺度图的能量系数重置法应用于设备故障诊断分析,能够有效的检测振动中反映局部故障的瞬态信号。更多还原

【Abstract】 With development of the science and technology, machines are developing in the direction of larger size, higher speed and more complicated structure, and machine fault will bring more serious effect, so fault diagnosis is becoming more and more important for industry, and has got great development in both theory and practice. The development of science and technology, especially the fast growth of processing technology of non-stationary signal provides potential method for the machinery fault diagnosis.This thesis mainly concerns the application of the fault diagnosis method based on time-frequency analysis in mechanical part fault diagnosis. The concept and property of STFT、WVD and CWT were expatiated via theoretical analysis and simulation and the CWT is found to be better for mechanical localized fault diagnosis. Based on the CWT representation of vibration signal, an automatic detection algorithm for signal transients is proposed, through which the periodical feature about the localized fault is overlapped and thus enhanced in the polar diagram and the feature about signal noise and about non-periodical components is de-noise oppositely. The application of the proposed algorithm in cone bearing localized fault shows that this method is rather effective in detecting the periodical transients for mechanical fault diagnosis. Based on the CWT representation, a mechanical fault diagnosis method through the reassignment of CWT coefficients, and the application of this method in cone bearing show effectiveness in representing the transient feature about the local fault in the time-scale plane.更多还原