Approximate Analytical Model of Oil-film Force for Cylindrical Journal Bearing

The mathematical model of journal bearing oil-film forcre is the basic and key work for analyzing the nonlinear dynamic stability of rotor-bearing systems.Based on dynamic boundary conditions of oil-film for cylindrical journal bearing,the pressure control Reynolds equation was solved using separation of variables method,and was decomposed into a similar long bearing model equation and the axial pressure equation because of the characteristics of separation of variables method,and the approximate analytical expression of oil film pressure distribution for cylindrical bearing was obtained.By integrating the pressure within the oil film region,we got the analytical expression of oil film force.The expression of the pressure was analyzed to study the pressure distribution,and the present model was compared with the long bearing oil film force,short bearing oil film force,and the finite difference method results.The results show that the proposed model in a wider length-diameter ratio range can accurately describe the oil film characteristics of plain journal bearing.And the proposed model is proved good efficiency by analyzing dynamics characteristic of a rigid rotor-bearing system.