A Nonlinear Model for Prediction of Dynamic Coefficients in a Hydrodynamic Journal Bearing

[摘要] This paper investigates the variation of nonlinear stiffnessand damping coefficients in a journal orbit with respectto equilibrium position. The journal orbit is obtained bythe combined solution of equations of motion and Reynoldsequation. In the linearized dynamic analysis, dynamic pressureis written as a perturbation of static pressure and pressuregradients at equilibrium position. However, in orderto obtain nonlinear dynamic coefficients about equilibriumposition, the dynamic pressure gradients in the orbit arealso written as the first order perturbation of static pressuregradients and higher order pressure gradients for displacementand velocity perturbations. The dynamic coefficientsare functions of bearing displacement and velocity perturbations.The higher order pressure gradients at equilibriumposition are evaluated at various eccentricity ratios and L/Dratios of 0.5 and 1.0. The variation of nonlinear dynamiccoefficients is analyzed for three Sommerfeld numbers ofa two-axial groove journal bearing under the action of anexternal synchronous load along and perpendicular to theradial journal load. Results indicate that the oil film nonlinearitiesaffect the journal motion at lower eccentricity ratios(higher Sommerfeld numbers) with wide variation in stiffnessand damping coefficients.

[学科分类] 力学，机械学