Research Of Composite Vibration Isolation System Based On MR Damping And Adjustable Quasi-Zero Stiffness

As the rapid development of science and technology,much higher requirements have been proposed in many engineering applications for vibration isolation technology,such as low-frequency vibration isolation in the sound stealth of submarine,environmental micro-vibration isolation of precision instrument,multi-mode vibration isolation during the launch of spacecraft and so on.However,conventional passive vibration isolation technology has poor vibration isolation performance in the low frequency band,and it can't meet the requirements of high-standard applications.Active vibration isolation technology has better vibration isolation performance in wide-band,but its energy consumption is large and the control is more complicated.Therefore,it is of great theoretical significance and application value to develop a new type of vibration isolation technology to improve the low frequency vibration isolation performance and the adaptability of the system,and to overcome the limitations of the conventional isolation technology.In order to achieve this goal,this paper takes vibration and noise reduction of power equipment in submarines as the application background,and develops a composite vibration isolation system based on magnetorheology damping and regulable quasi-zero stiffness.The new vibration isolation system combines the characteristics of passive,semi-active and active vibration isolation technology,and its damping and stiffness were all controllable.The specific research work of this paper includes: the design of outer multi-pole magnetorheology(MR)damper,the design and performance evaluation of electromagnetic quasi-zero stiffness unit,the dynamic analysis of the composite vibration isolation system and the experimental research of the system's performance.Firstly,the damping unit of the composite vibration isolation system is designed and researched.The outer multi-pole electromagnetic structure is introduced in the design of MR damper for the first time to improve the electromagnetic efficiency and dynamic range of the damping force.By analyzing and modeling the damping force characteristics of the MR damper,the effect of the main parameters on the damping force performance of the MR damper is studied,and the main structural parameters of the damper are optimized on this basis.Meanwhile,the damping performance of the MR damper is analyzed in combination with the electromagnetic finite element simulation.In addition,the outer multi-pole structure was modified to get the flow passage embedded in each magnetic core,in this way the electromagnetic efficiency can be further improved,and the modeling and simulation of the new damper is conducted.Secondly,the stiffness unit of the composite vibration isolation system is studied.An active electromagnetic quasi-zero stiffness(QZS)vibration isolator based on MR elastomer is proposed to solve the problems of conventional QZS isolator's relatively small loading capacity and narrow working range.The electromagnetic force phenomenological model of the negative stiffness unit is established by using electromagnetic finite element simulation,so the relationship between electromagnetic force and air gap & driving current is obtained,and the model is modified by experimental identification.The control system of electromagnetic QZS unit is established based on displacement feedback,and a customized driver board is developed to control the current loop.The static stiffness characteristics and adaptability of the proposed electromagnetic QZS unit prototype are evaluated by experimental tests.Thirdly,the nonlinear dynamics of the composite vibration isolation system is completely analyzed to study the coordination mechanism between damping and stiffness unit.The dynamic model of the composite vibration isolation system in normal working state is established,which can be solved by using the average method,and the effects of damping,nonlinear stiffness coefficient and excitation amplitude on the response and isolation performance of the system are studied.In addition,the effect of equilibrium position's shift on isolation performance is studied,and the corresponding dynamic model is solved by harmonic balancing method.The effect of the main parameters on isolation performance is analyzed,such as the offset,working range's width,excitation force and damping.Finally,a vibration testing platform of the composite vibration isolation system is set up,and the dynamic performance of each unit and the vibration isolation performance of the system are studied experimentally.The servo-hydraulic testing system is used to test the damping characteristics of the outer multi-pole MR damper,and the results showed that the dynamic range of damping force is greatly improved,which is in accordance with the design expectation.By controlling the experimental variables in vibration testing,the isolation performance of the QZS unit the composite vibration isolation system are comprehensively evaluated and researched.The results show that the composite vibration isolation system proposed in this paper has better isolation performance in low frequency domain and better adaptability than the conventional vibration isolation system.