Detection of a single rolling element bearings fault via relative shaft displacement measurement

Abstract

This paper describes with the investigation of using relative shaft displacement approach to detect early rolling element bearings fault. Rolling element bearings are among the most common elements used in the operation of rotating machines. However, they are one of the weak points in these machines where the majority of problems associated are caused by bearings failures. As a result, condition monitoring of the rolling element bearings is important in order to keep these machineries in their proper operating condition. Analysis and maintenance of any rolling element bearings failures are made much easier if any fault can be identified during its early stage. Thus, it is the aim of this research to investigate the relative shaft displacement technique for the early fault detection in rolling element bearings. Experiments were conducted on a rotor kit that simulates the actual behaviour of rotating machines. In order to simulate the early signs of fault developing, a single localized fault was induced on the outer race and the inner race for ball bearings and roller bearings, as well as on a rolling element of a roller bearing. Experimental data from the relative shaft displacement measurements due to dynamic vibrations of the shaft were analysed using time waveform analysis to detect the sudden changes in amplitude as a function of time. The experimental results show that fault signal is clearly present with positive or negative spikes, or both in the time waveform analysis depending on the type of fault that occurs and its location relative to the probe tip. Conversely, non-defective rolling element bearings exhibit a smooth time waveform curve.