Research On The Mechanical Characteristics Of Aero-engine Shaft High-speed Ball Bearings

With the development of science and technology, the performace of aero-engines is improved constantly. The ball bearing is widely used in aero-engines. Its mechanical properties exert important influence on the dynamic characteristics of rotor systems, especially at high speed. So the research on the mechanical characteristic of ball bearings is essential in order to meet the development of the new type aero-engines. The main contents of this paper are following.(1) The mechanical models of ball bearings are set up by both the quasi-dynamic method and the finite element method in this paper, and then the load distribution of ball bearings is studied. The rules of the contact angle, the deformation, the stiffness and the limit rotational speed in different structure parameters and load parameters are analyzed. The calculation results are compared with the results that obtained by experiment. It is found that the calculation results are close to the experiment values. The finite element mentod has advantages in calculational precision. On the other hand, the quasi-dynamic method has advantages in calculational efficiency.(2) The minimum oil film thickness and oil film stiffness characteristics of ball bearings are studied by the elastohydrodynamic lubrication theory. The synthetical stiffness of ball bearings is obtained by combination the contact stiffness with the oil film stiffness. The concept and the calculation menthod of the equivalent stiffness are presented in this paper. Taking the ceramic ball bearing used in micro turbine engines as an example, an experiment method for measuring the equivalent stiffness and the damping of the ball bearings is introduced. It is found that when the ratio of frequency is less than 1, the equivalent stiffness will be increased with the rising of the rotational speed in the certain conditions.(3) Considering the effect of balls and the radial clearance, the formula that calculates the fatigue life of ball bearings is modified. It is found that the effect of...