Simulation of Subcritical Vibrations of a Large Flexible Rotor with Varying Spherical Roller Bearing Clearance and Roundness Profiles

Abstract

In large rotor-bearing systems, the rolling element bearings act as a considerable source of subcritical vibration excitation. Simulation of such rotor bearing systems contains major sources of uncertainty contributing to the excitation, namely the roundness profile of the bearing inner ring and the clearance of the bearing. In the present study, a simulation approach was prepared to investigate carefully the effect of varying roundness profile and clearance on the subcritical vibration excitation. The FEM-based rotor-bearing system simulation model included a detailed description of the bearings and asymmetricity of the rotor. The simulation results were compared to measured responses for validation. The results suggest that the simulation model was able to capture the response of the rotor within a reasonable accuracy compared to the measured responses. The bearing clearance was observed to have a major effect on the subcritical resonance response amplitudes. In addition, the simulation model confirmed that the resonances of the 3rd and 4th harmonic vibration components in addition to the well-known 2nd harmonic resonance (half-critical resonance) can be significantly high and should thus be taken into account already in the design phase of large subcritical rotors.

Simulation-Based Transfer Learning for Support Stiffness Identification

“…The experimental setup, measurement procedure, the simulation model and its parameters are briefly described in the following sections. More details about the experimental setup can be found in previous research [37] while the details related to the simulation model are available in [38].…”

“…To that end, a high-fidelity, rotor-bearing-support model of the test rotor is used. The model, which has been experimentally validated before [40], [38], uses 3D beam elements based on the Timoshenko beam theory for obtaining computationally fast and yet accurate dynamic response. Figure 3 shows the FE discretized sketch of the rotor along with its dimensions.…”

“…Figure 3 shows the FE discretized sketch of the rotor along with its dimensions. The asymmetry of the tube section of the rotor is included by varying the thickness of the cylindrical section based on ultrasonic measurement similar to [38]. The thickness variation is implemented in the model by defining the thickness profiles of the cross sections along the length of the tube structure, thus affecting the area moment of inertia.…”

Development and verification of frequency domain solution methods for rotor-bearing system responses caused by rolling element bearing waviness

“…The simulated model emphasized the significant effect of half critical subharmonic vibrations. Kurvinen et al [29] further expanded the study by including the effects of the third and fourth waviness components.…”

Effect of Rotor Geometry on Bending Stiffness Variation

“…An inner surface can be measured using the geometry of an outer surface for example with an ultrasonic probe [14]. The procedure can be used for workpieces in which both surfaces are smooth, such as paper machine rolls [4,15,16]. A direct roundness measurement on an inner surface is also possible, but it is challenging due to the lack of space and difficult access especially with slender rotors.…”