Transient Vibration Prediction for Rotors on Ball Bearings Using Load‐Dependent Nonlinear Bearing Stiffness

Fleming, D. P.; Poplawski, J. V.

doi:10.1155/s1023621x0400048x

Cited by 5 publications

(2 citation statements)

References 4 publications

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“…Response at stations 7 and 10 (the imbalance and right bearing locations) was examined for speeds of 20 000 to 80 000 rpm. Although larger than allowed by the standard for a well-balanced rotor, these imbalances are considerably less than those produced by a blade loss; Fleming and Poplawski [4] used imbalances of 3.6 to 57.6 g•cm in their study of transient vibration.…”

Section: Analytical System and Proceduresmentioning

confidence: 99%

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Unbalance Response Prediction for Rotors on Ball Bearings Using Speed‐ and Load‐Dependent Nonlinear Bearing Stiffness

Fleming

Poplawski

2005

International Journal of Rotating Machinery

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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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Section: Analytical System and Proceduresmentioning

confidence: 99%

“…In a previous paper by the authors (Fleming and Poplawski [4]), COBRA-AHS was used in conjunction with a transient rotordynamics code to calculate response to a suddenly applied large imbalance simulating a blade loss. The results obtained with nonlinear bearings could not be duplicated with any average bearing stiffness value.…”

Section: Introductionmentioning

confidence: 99%