Theoretical, Simulation And Test Research On Stiffness Characteristics Of Faulty Rolling Bearings

The performance of the aero-engine improves as the technology develops.The antifriction bearing is widely used in the aero-engine rotor system and its mechanical property has great effect on the dynamic property of the rotor system, especially when the speed is high.Therefore, to meet the demand of the development of the new generation of the advanced aircraft engine, the research on the high speed bearing in the aero-engine is necessary.The analytical method, finite-element analysis method and tests are used to analyze the stiffiess characteristic of the bearing under different loads.The faults that usually appears in the engineering practice are applied in the model to analyze the changes of the stiffness of the bearing under fault condition.The researches are shown in details as follows:(1) The structure characteristics of the deep groove ball bearing and the angular ball bearing are described, and the Hertz elastic contact theory, rigid ring hypothesis and other basic theories are introduced in the paper.According to the deformation of the ball under the loads, the stiffness expression of the contact point between the ball and the inner and outer ring is derived through the Hertz theory.(2) The analytical calculation models of the stiffness of the angular contact ball bearing are built in three conditions:health status, single point corrosion failure status and ball missing failure status, the angular contact ball bearing 71807AC is considered as an analysis of examples to study the change law of the axial stiffness and the radial stiffness with the variation of the axial loads and the radial loads and the effect of the fault size on the stiffness.Compare the stiffness characteristic of the bearing under health status, single point corrosion failure status and ball missing failure status to study the effect of the bearing fault on the stiffness characteristic.(3)The finite element models of the stiffness characteristic of the angular contact ball bearing and the cylindrical roller bearing are built based on the finite element analysis method in consideration with the effect of the ferrule deformation, the change laws of the stiffness of the bearing with the loads are discussed under axial loads, radial loads and axial-radial loads.(4) The finite element models of the angular contact ball bearing under single point corrosion failure status and ball missing failure status are built and the stifness characteristics law of the angular contact ball bearing under different status are compared.(5) The static stiffness testing of the angular contact ball bearing test-bed is constructed to test the axial displacement and the radial displacement of the angular contact ball bearing under health status and ball missing failure status, then the axial stiffness and the radial stiffness of the angular contact ball bearing can be calculated.A good repetition of the test method is validated through sufficient replicates of the test.The results of tests, analytical methods and the finite element method show good agreements.