A Number Of Problems Researches For Nonlinear Dynamics Of Bearing-Rotor System

The rotational machinery are widely used in many engineering fields such as mechanism, power , aviation and spaceflight. With the rapid advances of engineering and technology, the designs of rotating machinery are increasingly developing towarg to large power, high speed and flexibility. Meanwhile,many phenomena such as chaotic and quasi-period movement that are not interpreted by linear theory appear and bring about a lot of serious accidents.This task-a number of problems researches for nonlinear dynamics of bearing-rotor system,comefrom National Engineering Research Center of Turbo genetator Vibration. Based this background, this paper studies the some non-linear dynamic problems existing in bearing-rotor system using numerical integral method. The results give some theoretical basis to the designs of similar systems and have specified engineering signifance.First.the paper introduces basical nonlinear theory frequently used in the study of bearing-rotor systems and a accurate model of nonlinear oil-film force. The nonlinear dynamic behaviors of bearing-rigid rotor system are extensively investigated. The results show that there exists such nonlinear dynamical phenomena as chaos ang quasi-period movement when the rotational speed , mass eccentric and a synthesizing parameter of the system change. From different point of view,the chaotical phenomenen induced by double period bifurcation is found.In this paper, the dynamical model of bearing-elastical rotor with a cross-section of crack is estabilished. The influence of whirling motion of the shaft to opening regularity of crack is considered. The nonlinear dynamical behaviors on some parameters are studied. The results have certain sigfinance to the inspection and diagnose of troubles of similar rotational machinery.In fact, the bearing with finite width are widely used in rotational machinery. But the calculation of oil-film force of this kind of bearing needs a large mount of time,and analytical method is powerless to this problem. Considering of above reasons, this paper leads into averageing natural value method that can meet the requirment of engineering. Using this method ,the paper investigate the some nonlinear dynamical behaviors of bearing-rotor system.At the end of this dissertation ,research works to bring forth new ideas for this dissertation are sumarried ,and nesrssary research problems to go a step further are pointed out too.