A new field unbalance estimation method for flexible rotors

Current field unbalance estimation methods regards "flexible rotors with lumped mass" as the main research object, and most of them need a stop running to take trial weights. Due to its test speed closing to the critical speed, the process of balance is really complicated and dangerous. This paper concerns rotors which unbalance state shows a continuous spatial distribution. Firstly, a dynamic finite element (FE) model of the rotor system is built, the inherent relations and differences between the dynamics transfer matrix and influence coefficient (IC) matrix are analyzed, and then, an extended dynamics matrix with arbitrary dimension is obtained based on the principle of IC balancing method. Secondly, the continuous distribution mass eccentricity curve is represented as mass eccentricity point on each FE model node, and the unbalance forces imposing on each FE model node are identified by the extended dynamics matrix. Finally, the theoretic analysis and experiment is presented to verify this method, and the result shows that unbalance forces on all FE model nodes can be identified accurately with less measuring points, and higher order modal components of the distributed unbalance are balanced effectively.