An innovative rotordynamical model for coupled flexural-torsional vibrations in rotating machines

Abstract

Flexural and lateral coupled vibrations usually exist in rotordynamics applications, as it is caused by common malfunction conditions and complex distributed inertial elements connected to the shaft may determine the coupling as well. In the paper, the authors present an accurate, innovative and fully coupled finite element (FE) rotordynamics formulation with 6 DOFS for each node for the evaluation of the dynamic behaviour of multi-rotor systems that has been conceived with the goal of investigating the flexural-torsional interaction. The model is able to model long rotors of complex topology, such as rotor with distributed inertias or connected simultaneously in several points, couplings and gear-boxes and it uses coupled shape-functions. The model proposed represents a systematic and practical approach to the rotordynamics modeling issue and its main contribution to the research topic of coupled flexural-torsional vibration in rotors is due to its general topology. The effectiveness of the model in predicting the critical behaviour of the a flywheel masses test bench has been preliminary tested by means of experimental data of vibration tests campaign, performed in collaboration with Politecnico di Milano.