A comparison of on-bearing and shaft torsional vibration for blade vibration

Rotating blades are considered as the most common cause of failures in rotating machinery. In the present research study, the dynamics of the blades both in the healthy and cracked conditions are studied on a small experimental rig using the on-bearing vibration and shaft torsional vibration which are measured using the accelerometer and the incremental shaft encoder. The measured vibration and encoder data are analyzed by computing the responses at different engine orders (EOs) related to the blade resonance frequencies and their higher harmonics to understand the behaviour of the blades. The observations suggest that the shaft torsion vibration can be extended to the non-intrusive method for the blade health monitoring (BHM) when compared with the on-bearing vibration. The paper presents the rig, experiments conducted and measurements, data analysis and the results.