Dynamic Response Analysis Of SFD-Cantileverbearing Rotor System

Miniature rotary machine has the characteristics of complex structure and high precision, the abnormal vibration often causes an accident during the operation. Using a shock absorber is an effective way to reduce abnormal vibration, and squeeze film damper is applied more widely used as a shock absorber, it has a compact structure and can reduce vibration significantly, it also can solve the problem of buckling caused by vibration, which can ensure that the equipment running smoothly. But not all of the squeeze film damper can reduce vibration and improve the stability of the system. By designing reasonable parameters of the damper and adjusting the degree of match between the parameters and system parameters, we can achieve the vibration damping effect. In order to fill the blank of the squeeze film damper used in the cantilever rotor- bearing system, this paper analyses the SFD-sliding bearing cantilever rotor system, and makes a research on dynamic response and critical speed through the combination of theoretical analysis and numerical simulation, and this paper also makes the dynamic performance of the system to achieve the best through allocating a reasonable parameters, and establishes a set of design optimization about SFD-sliding bearing cantilever rotor system. The main results obtained during the study:(1) This paper establishes the mechanics model of SFD-rigid shaft sliding bearing cantilever rotor system, provides its equation governing the equation of motion and uses numerical analysis method to solve the differential equation, thus acquiring the dynamic response and critical speed of the system. The study has shown: the system goes through successively single periodic motion,quasi-periodic motion, chaotic motion. The first critical speed of the system is 5250r/min.(2) This paper establishes the mechanics model of SFD-flexible shaft sliding bearing cantilever rotor system.The flexible shaft system compares with the rigid shaft system on the system dynamic response and the critical speed. The study has shown: the flexible shaft system goes through successively single periodic motion, quasi-periodic motion, chaotic motion, double periodic motion, quasi-periodic motion, chaotic motion. And it is much more complex than a rigid shaft system in terms of the dynamic response. The first critical speed of the system is 4890r/min. The second critical speed of the system is 7735r/min.(3) On the basis of SFD-flexible shaft sliding bearing cantilever rotor system,this paper analysis the impact system parameters on natural frequency and amplitude,and get the sensitivity of system parameter. The study has shown: the sensitivity value is relatively high on bearing clearances, bearing radius, clearance damper, shaft stiffness,and these four parameters have greater impact on critical speed and amplitude. The selection of these four parameters is essential on the optimization.(4) On the basis of sensitivity analysis, this paper employed genetic algorithm to give an optimization analysis on SFD-flexible shaft sliding bearing cantilever rotor system. The optimization goal is making the amplitude of the system minimum at a constant rotate speed.At a constant speed of 5730r/min(600rad/s),the value of vibration amplitude from the original 4.059e-06 m fell to 3.174e-06 m by optimizing,and reduce 21.8%. The first critical speed from 4890r/min fell to 4775r/min. The second critical speed from 7735 r/min fell to 7450 r/min.Operating speed keep away from the critical speed, and the optimized results is better by analyzing.