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

摘要

Rolling-element bearing forces vary nonlinearly withbearing deflection. Thus an accurate rotordynamic transientanalysis requires bearing forces to be determined at eachstep of the transient solution. Analyses have been carriedout to show the effect of accurate bearing transient forces(accounting for nonlinear speed and load-dependent bearingstiffness) as compared to conventional use of average rolling-elementbearing stiffness. Bearing forces were calculated byCOBRA-AHS (Computer Optimized Ball and Roller BearingAnalysis—Advanced High Speed) and supplied to therotordynamics code ARDS (Analysis of Rotor Dynamic Systems)for accurate simulation of rotor transient behavior.COBRA-AHS is a fast-running five degree-of-freedom computercode able to calculate high speed rolling-element bearingload-displacement data for radial and angular contactball bearings and also for cylindrical and tapered roller bearings.Results show that use of nonlinear bearing characteristicsis essential for accurate prediction of rotordynamicbehavior.