Performance evaluation of touchdown bearing using model-based approach

Abstract

In the active magnetic bearings (AMBs) supported rotating machinery, touchdown bearings are considered as safety devices to support the rotor in the deficiency of electromagnetic field. Generally, the industrial AMB machines do not have force sensors for touchdown bearings and the system is only equipped with the position sensors to monitor the rotor displacement that disables the opportunity to measure the forces during dropdown events that might be destructive for the safe operation of the rotor system. This study explores the relative severity of dropdowns that are evaluated from a computational rotor model using the rotor displacement data recorded from the position sensors installed in the machine as an input. The model for double-row angular contact ball bearing type touchdown bearings is integrated with the rotor model. The simulation model is verified by comparing the simulated rotor orbits against measured orbits at four different dropdowns. The Fast Fourier transform (FFT) is used to observe the studied dropdown events in frequency domain revealing from the rotor response the following details: harmonics of the operation speed, rub-impact frequencies, pendulum motion of the rotor and the first two bending frequencies of the rotor settled on the touchdown bearings. The critical speed map also verifies the bending frequencies and identified support properties. The model-based approach can be used to evaluate and compare a single dropdown event with respect to previous events providing an insight for decision making whether touchdown bearing should be replaced.

Design Space Method for Conceptual Design Exploration of High Speed Slitted Solid Induction Motor

“…The auxiliary bearings also effect the end shaft dimensions. Usually angular contact ball bearings (ACBB) are used as auxiliary bearing because of their ability to carry high axial and radial loads in touchdown events [28]. The bearing should be able to rotate at the same speed as the operational speed of the rotor, which becomes a limiting factor for the bearing bore diameter and consecutively the shaft diameter of that section, d end .…”

Investigations on the dynamic behaviour of an on-board rotor-AMB system with touchdown bearing contacts: modelling and experimentation

“…The harmonic translation support motion was set to 20 Hz ranging from 0.1 to 1.1 G, see Fig. it is a representative frequency of earthquake whose energy is mainly comprised in the range [20][21][22][23][24][25][26][27][28][29][30] Hz, as explained by Matsushita et al [28]. The targeted acceleration level was applied progressively, during almost 30 s, to limit overshoots and was then maintained for approximately 40 s to analyse potential onset of nonlinear dynamic regimes.…”