Experimental observations in the shaft orbits of relatively flexible machines with different rotor related faults

• An experimental study on the shaft orbit response for rotor faults is presented.
• Experiments are done on a laboratory ball bearing rig at subcritical speeds.
• The dynamic responses of a baseline and six different rotor faults are studied.
• The present work provides useful results for practical rotor fault diagnosis.
• This study offers useful results to analytical works on the faults observed here.

An experimental study on the shaft orbit response for different rotor related faults is presented in this paper. Similar previous studies in readily available literature were done considering a few fault conditions on different machines. Therefore, an opportunity exists to provide further insight to changes in the behaviour of a single machine when affected by a wider range of different rotor related faults. Experiments are done on a small laboratory ball bearing rig on which vibration displacement data are acquired for a baseline condition as well as six different fault conditions that are introduced separately at different subcritical steady state speeds. For each condition tested, orbit plots are generated and critically analysed. These orbits are also compared to those observed on a similarly configured rig with different dynamic characteristics on which the same experiments are done in order to assess any changes in the shaft orbit. The present work provides useful results for practical rotor fault diagnosis as well as worthwhile qualitative information to analytical studies related to the rotor faults observed here.