Nonlinear Dynamics And Vibration Control Of Field Modulated Magnetic Gear

The transmission of the field modulated magnetic gear(FMMG),which utilizes the interaction of the magnetic coupling,is contact-free transmission.It has the advantages of no wear,low vibration and noise,soft start,and automatic overload protection ability,etc.However,the nonlinear magnetic coupling stiffness easily causes the system instability,which makes the dynamic behavior of the FMMG system more complicated.In this dissertation,the nonlinear dynamics and vibration control strategies of the FMMG system are studied.The specific research contents are as follows:Forced vibration of the magnetic gear nonlinear system.Considering the nonlinear magnetic coupling force between the components of the FMMG,the nonlinear dynamic model and the nonlinear differential equations with quadratic nonlinearities are established.The response expressions of the main resonances and superharmonic resonances are obtained by multi-scale method,and the response laws of magnetic gear nonlinear system are analyzed.When the main resonances or superharmonic resonances occur,the strong vibration will occur,and the dominant frequency of the responses is the natural frequency of the system.Nonlinear forced vibration of the magnetic gear nonlinear system with the internal resonance.The approximate analytical solutions of the free vibration and forced vibration of the system are obtained by multi-scale method when the torsional modal frequency of the output rotor is twice as much as that of the input rotor,and the vibration characteristics of the FMMG under the action of internal resonance are analyzed.It is found that internal resonance can deteriorate the dynamic behaviors of the FMMG system.Vibration control of the magnetic gear based on magnetorheological damper(MRD).Through the mechanical performance test,the damping force characteristic curves of the MRD are obtained under different currents and displacement signals.According to the test results,the parameters of the Bingham model and the hyperbolic tangent function-based model(HTFM)are identified.By comparing and analyzing the curve fitting effects of the two mechanical models,it is found that the HTFM can better describe the output damping force of the MRD,and the accuracy of the mechanical model is verified by the simulation model.The frequency response of the magnetic gear transmission system with MRD are obtained by the Runge-Kutta methods,and the influences of different control methods on the vibration characteristics of the system are discussed.It is found that the Skyhook damping semi-active control method possesses relatively better vibration suppression effect.Development and experimental research of concentric magnetic gear prototype.The field modulated magnetic gear prototype are carried out.A magnetic gear vibration reduction test platform are built.A vibration reduction experiment based on MRD are carried out.The dynamic response curves of the magnetic gear prototype under sinusoidal excitation are obtained.By comparing and analyzing the vibration response of the magnetic gear prototype with and without the MRD,the vibration suppression effect of the damper on the FMMG drive system is verified.