Spline Coupling Induced Nonsynchronous Rotor Vibrations

Abstract

A mathematical model for predicting spline coupling induced nonsynchronous rotor vibrations is developed, and the predictions are compared with data from a rotor dynamics test rig. The special feature of the spline model is the characterization of the friction forces that are produced at the mating spline teeth surfaces and subsequent calculation of the internal damping coefficients. The spline internal damping and the r esulting rotor instabilities are predicted for four different spline configurations and the solution results are correlated with measured data from a gas turbine rotor simulator test rig.

Effects of Anomalous Rotor Joints on Turbomachine Dynamics

“…Frictional effects are usually simulated in linear analysis by equivalent viscous damping. Marmal et al (8) so simulate a spline coupling in calculating onset of friction induced rotor instability. However, their equivalent viscous damping coefficient is based on the total energy dissipated by friction rather than the energy transmitted into subsynchronous motion of particular joint flexing amplitude and whirl speed.…”

Analysis of the Coupled Lateral Torsional Vibration of a Rotor-Bearing System With a Misaligned Gear Coupling

“…In terms of Marmol [3] the energy dissipation of the subsystem is from the internal damping of the coupling, which is a source of instability vibration. Then Rayleigh dissipation function R I in the rotating co-ordinate system can be expressed as…”

“…The potential energy function ; of the subsystem consists of two parts, one part is from the elastic deformation of the rotor sections beside the coupling, another part from the teeth deformation of the coupling that was modelled by Marmol [3] with the lateral and angular sti!ness coe$cients of the coupling.…”

“…In the past discussions on gear coupling, the frictional forces between the teeth of couplings and its e!ects on the stability of the rotor systems were the mainly concern. Marmol et al [3] developed a mathematical model to predict the lateral vibration of a rotor system connected with spline coupling; however, in their model some major assumptions were made, one of them was that all teeth of the coupling carry about the same load, which means that the coupling is in &&perfect alignment''. Nawate and Terauchi [4] analyzed the number of teeth in contact with the gear coupling considering the teeth errors; after calculating we found that there are few teeth in contact in some cases.…”

Meshing Force of Misaligned Spline Coupling and the Influence on Rotor System

“…There are many discussions in the industry regarding the stiffness, damping, and wear of spline coupling. Marmol et al [10] developed a mathematical model to predict the lateral and angular stiffness and damping coefficients of spline couplings. Based on these coefficients, they calculated the natural frequencies of a rotor system and compared them to the experimental data.…”