Internal clearance behaviour in healthy and faulty bearings

Internal clearance is a critical parameter in bearing design and operation because it affects the bearing's performance. It can be considered as a special type of the looseness fault. Several studies indicate that rolling bearings with large internal clearances showed a short predicted fatigue life. However, the time waveform and spectral features of bearing with internal clearances are partially studied and require further studies. To address this gap, the purpose of this paper is to study the effect of internal clearance on the dynamic response of healthy and faculty rolling bearings in both time waveform and spectral representations. Four experiments are designed and performed: (1) rigid bearing with no defect, (2) rigid bearing with bearing defect, (3) bearing with high internal clearance, (4) bearing with high internal clearance and bearing defect. The results indicate an increase in the overall vibration level with high internal clearance is introduced, however, there is an increase in the overall vibration level when high internal clearance and bearing defect are both presented. The internal clearance negatively affects the impact amplitude of the bearing defect, which also affects the spectral pattern at the natural frequency zone.