Unbalance Response Prediction for Rotors on Ball Bearings Using Speed- and Load-Dependent Nonlinear Bearing Stiffness
Rolling-element bearing forces vary nonlinearly with bearing deflection. Thus, an accurate rotordynamic analysis requires that bearing forces corresponding to the actual bearing deflection be utilized. For this work, bearing forces were calculated by COBRA-AHS, a recently developed rolling-element b...
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| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
Wiley
2005-01-01
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| Series: | International Journal of Rotating Machinery |
| Subjects: | |
| Online Access: | http://dx.doi.org/10.1155/IJRM.2005.53 |
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| Summary: | Rolling-element bearing forces vary nonlinearly with
bearing deflection. Thus, an accurate rotordynamic analysis
requires that bearing forces corresponding to the actual bearing
deflection be utilized. For this work, bearing forces were
calculated by COBRA-AHS, a recently developed rolling-element
bearing analysis code. Bearing stiffness was found to be a strong
function of bearing deflection, with higher deflection producing
markedly higher stiffness. Curves fitted to the bearing data for a
range of speeds and loads were supplied to a flexible rotor
unbalance response analysis. The rotordynamic analysis showed that
vibration response varied nonlinearly with the amount of rotor
imbalance. Moreover, the increase in stiffness as critical speeds
were approached caused a large increase in rotor and bearing
vibration amplitude over part of the speed range compared to the
case of constant-stiffness bearings. Regions of bistable operation
were possible, in which the amplitude at a given speed was much
larger during rotor acceleration than during deceleration. A
moderate amount of damping will eliminate the bistable region, but
this damping is not inherent in ball bearings. |
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| ISSN: | 1023-621X 1542-3034 |