| The development of modern industry put forward higher request for the bearing system of high-speed rotating machinery.Bump foil bearings have a broad development prospects in the micro mechanical and aerospace and other fields because of its high bearing capacity,good and strong anti-interference ability.This paper models the laboratory’s bump foil bearing and rotor supported by the bearing,and based on this model its rotor dynamic characteristics is analyzed.Then the rotor dynamic characteristics test bench is built to determinate the rotor vibration parameters and to analyze its movement characteristics.The lumped parameter method is used to establish the bump foil bearing rotor system model,motion equation of the system is established on the basis of the model.Based on the motion equation,the free vibration modal,the response caused by unbalance excitation and the dynamic stability are researched.Researches show that the rotor system at first order critical speed is in unstable state,while it at high-order critical speed is in stable state,but the total stability of the rotor under low speeds is more stable than it under high speed.Speed’s influence on nonlinear mode of vibration is analyzed by establishing partial model of a journal bearing-rotor system under these two types of force,calculating the rotor’s response under increasing speed and observing chaotic motion and bifurcation.Researches show that the nonlinear characteristic of the system under different rotation speeds also show differences,the system movement under the speed away from the critical speed zone shows obvious disorder charactors.The bump foil bearing rotor system dynamic characteristics test bench is designed and built to test rotor’s displacement under different rotational speeds.Experimental results show that the rotor’s vibration is mainly in low frequency and has big amplitude before departure,while it is in basic frequency and has smaller amplitude after departure. |
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