Lubrication Performance Of Porous Bearings

The porous bearings are extensively used in mechanical engineering and so on. The goal of this thesis is to study the lubrication performances of porous bearings. The theoritical models, structure models, failure forms of the porous bearings were reviewed and analyzed. And, theoritical model of porous bearings and the numerical solution of the lubrication process in porous bearings were developed. Thus, the distributions of the pressure and film thickness with the new modified Reynolds equation were calculated out.In first chaper, the developing history and current situation of theory and structure models of the porous bearings at home and abroad were briefly reviewed, and the main factors which influence the lubrication performance of the porous bearings were summarized. Moreover, failure forms and mechanism of the porous bearings were analyzed. And then the contents and the frame of this research thesis were presented.In chapter 2, the mathematical and physical model for the lubrication of the porous bearings was established. The mathematical and physical model included modified Reynolds equation, viscosity and density equations of the lubricant, film thickness equation, load equation, which based on the modification of Darcy law and the lubricant whose viscosity and density are variable with hydrodynamic pressure.In chapter 3, the basic concept, the estimate of truncation error, convergence, stability of Euler method, indicated the conformation and absolute stability of Runge-Kutta method were put forward. The basic idea, definition and convergence of Newton-Raphson method for us to solve the above mathetical-physical model were discussed.In chapter 4, difference methods such as Guass iterative method and Simpson integral method were adopted to analyze the lubrication process. The numerical solution of the porous bearings was presented, and the modified Reynolds equation, viscosity and density equation of the lubricant, film thickness equation and load equation for the porous bearings were resolved. The distributions of the pressure and film thickness were obtained. The effects of the velocity, load and the permeability on the distribution of the pressure and film thickness have been obtained.In chapter 5, results of this thesis were summarized, and the further research directions of the lubrication performance of porous bearings were proposed. The maximum hydrodynamic pressure and load capacity of the porous bearing become higher with the increase of the rotation speed of the shaft. The radial load has quite influences on the film thickness and hydrodynamic pressure. The hydrodynamic pressure is higher as the load becomes larger, and the minimum film thickness reduces at the same time. The permeability of the porous bearings has effects on pressure distribution and film thickness of oils, and the maximum hydrodynamic pressure and film thickness reduce for larger permeability factor.This project was supported by a collaboration project between Poland and China governments. (Grant AM30:034(30-18))...