Rubbing is an important problem in machinery industry which occurs when a rotating element hits a stationary part. This rotor-to-stator rub may result in the catastrophic breakdown of the machine. In this work, the phenomenon of rotor rubbing is analyzed from the perspective that the signal analysis tools that are in use today to detect this defect emphasize or highlight particular aspects of the studied phenomenon. So, sometimes it is necessary to use more than one tool to deepen the understanding of the problem. For this purpose, laboratory tests were performed on a rotor system with a rubbing mechanism, while mechanical vibrations were measured with an accelerometer and a data acquisition system. Experiments were carried out for fixed rotor speed, and for run-up and run-down rotor speed conditions. The analysis approach included various processing tools to study their capabilities in rubbing detection: Root Mean Square (RMS), Fourier transform, Wavelet transform and Hurst exponent. Fixed rubbing conditions show similar results for RMS and Hurst exponent on the information obtained. For variable run-up and run-down rotor speed conditions, the Hurst exponent shows predictability, a fact that can be used for rub detection. However, the Wavelet and Fourier Transforms operated in a very distinct way. Although both transforms give frequency information, Fourier transform results in a more detailed frequency analysis, while the Wavelet transform can give time localization of the rubbing phenomenon.

中文翻译：

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转子摩擦机械振动分析信号处理工具性能的实验研究

摩擦是机械工业中的一个重要问题，当旋转元件撞击静止部件时会发生摩擦。这种转子与定子的摩擦可能导致机器的灾难性故障。在这项工作中，从当今用于检测该缺陷的信号分析工具强调或突出所研究现象的特定方面的角度分析了转子摩擦现象。所以，有时需要使用不止一种工具来加深对问题的理解。为此，在带有摩擦机构的转子系统上进行了实验室测试，同时使用加速度计和数据采集系统测量了机械振动。针对固定转子速度以及加速和减速转子速度条件进行了实验。分析方法包括各种处理工具来研究它们在摩擦检测中的能力：均方根 (RMS)、傅里叶变换、小波变换和赫斯特指数。固定摩擦条件在获得的信息上显示了 RMS 和赫斯特指数的相似结果。对于可变加速和减速转子速度条件，Hurst 指数显示出可预测性，这一事实可用于摩擦检测。然而，小波和傅里叶变换以非常不同的方式运行。虽然两种变换都给出了频率信息，但傅里叶变换会产生更详细的频率分析，而小波变换可以给出摩擦现象的时间定位。固定摩擦条件在获得的信息上显示了 RMS 和赫斯特指数的相似结果。对于可变加速和减速转子速度条件，Hurst 指数显示出可预测性，这一事实可用于摩擦检测。然而，小波和傅里叶变换以非常不同的方式运行。虽然两种变换都给出了频率信息，但傅里叶变换会产生更详细的频率分析，而小波变换可以给出摩擦现象的时间定位。固定摩擦条件在获得的信息上显示了 RMS 和赫斯特指数的相似结果。对于可变加速和减速转子速度条件，Hurst 指数显示出可预测性，这一事实可用于摩擦检测。然而，小波和傅里叶变换以非常不同的方式运行。虽然两种变换都给出了频率信息，但傅里叶变换会产生更详细的频率分析，而小波变换可以给出摩擦现象的时间定位。