Study On Dynamical Properties Of Oil Film And Pressure Extremum Under Line Contact EHL State

Line contact exists in many mechanical elements, such as gear, rolling bearing and so on. These elements are always working in the state of Elastohydrodynamic Lubrication. In practical application, when engineers conduct the dynamical properties analysis and strength design for these elements, the effects of lubrication are always neglected. With the development of industrial manufacture to be with high speed and high stability, the demand in strength and dynamics is also rapidly increasing for these elements, thus in-depth study on the analysis of both dynamics and strength under EHL state become very urgent for the design of high performance rotor systems.Firstly, the mathematic models of steady and unsteady EHL problem under line contact were introduced. We programmed the calculation code and verified their accuracy through comparing the numerical computing results.Then we linearized the oil film and built the calculation model of stiffness and damping. We established the coupling model under the conditions of displacement perturbation, harmonic excitation perturbation and transient load perturbation for analysis and calculation of the stiffness and damping. Furthermore, the impact of initial perturbation on the dynamical properties of oil film was analyzed, and the influence of various factors, such as load, speed and harmonic frequency, on the dynamic characteristics of contact pair was studied in this thesis also. The results show that the stiffness and damping of oil film both increase with load rising and decrease with speed falling; the initial perturbation has no influence on the stiffness and damping of oil film.Finally, the effects of load, speed and material parameters on the amplitude of central pressure and pressure spike were investigated under line contact EHL condition. Based on the analysis of mass numerical data and regression, the fitting formulas of amplitude of central pressure and pressure spike of line contact EHL state were proposed and the accuracy of fitting formulas was verified. The results show that in a fairly wide range of the parameters, the accuracy of fitting formulas is satisfactory, which can completely meet the demands of engineering designs.