Vibration Measurements and FE Modeling Tools in Root Cause Analysis (I.)

摘要

A bearing damage had occurred during balancing of a generator rotor in the high speed balancing facility. Analysis of findings from vibration measurements data, together with FE modeling and dynamic analysis of the rotor lead to the conclusion that the rotor had undergone run out changes as a result of dynamic bending conditions that affected the coupling hub, which was shrunk onto the main rotor shaft as a part of previous repair for salvaging the rotor. The bearing wipes occurred as a result of the bending modes due to bows generated by the change in coupling conditions at second and third critical speeds. The main lesson learned from this case was that when solving rotor mechanical problems, one couldn't ignore the need to perform rotor dynamic analysis and the effect on the repair.