Optimization Design And Experimental Study Of Small Vibration Isolation Bearing Based On Magnetic Sensitive Rubbers

Integrated systems and precision instruments are vulnerable to the interference of micro-vibration in complex engineering environment,which has a negative impact on the stability and reliability of the system.In the field of micro-vibration control,the isolation system mostly adopts the method of external sensors,which has the disadvantages of high installation complexity and slow response speed.The use of magnetic sensitive rubbers with excellent mechanical and sensing properties to design vibration isolation bearing makes it possible to realize functional devices integrating sensing and execution.However,the traditional magnetic sensitive rubbers vibration isolation bearing can only be used for the perception and isolation of unidirectional vibration loads.In practical engineering applications,complex vibration loads are multi-directional or multi-angle.If the existing magnetic sensitive rubbers vibration isolation bearing are applied in complex working conditions,it is likely that their own structure is not reliable,resulting in structural damage,detachment,collapse and other phenomena during service,and even make the vibration isolation bearing structure completely destroyed and lose the ability to resist complex vibration.In this thesis,a small vibration isolation bearing based on magnetic sensitive rubbers is taken as the research object.focusing on the micro-vibration conditions under multi-directional loads,and conducting optimization design on the basis of traditional magnetic sensitive rubbers vibration isolation bearing structure,so that its structure is miniaturized and has the structural characteristics of structural self-adaptation and impact self-protection.The self-sensing performance test of the bearing is carried out,and then the control system is designed to complete the vibration isolation experiment of the control.The main contents of this thesis as follows:1.The background and significance of research on a small vibration isolation bearing based on magnetic sensitive rubbers are described.The application of magnetic sensitive rubbers in the field of vibration isolation and sensing,micro-vibration control technology and self-sensing and controlled vibration isolation are reviewed.After summarizing the problems existing in the research progress of this subject,the main research contents of this thesis are put forward.2.Considering that in order to realize intelligent vibration isolation of vibration isolation bearings,first of all,it is necessary to make its own structure safe.Based on theexisting structure of laminated magnetic sensitive rubbers vibration isolation bearing,the mechanical structure optimization scheme and magnetic circuit structure optimization scheme of vibration isolation bearing are proposed.In the optimization of mechanical structure,The limited magnetic conductive steel plate is specifically designed and laminated with the magnetic sensitive rubbers as the core vibration isolation unit of the bearing.A ring arrays locking mechanism is designed between the top cover of the support and the side sleeve.The minimum optimization method with constraints is used to calculate the minimum mechanical structure size and its optimal proportion of the total magnetoresistance.The size of the magnetic sensitive rubbers vibration isolation bearing is miniaturized,and it is suitable for the precision system or equipment with small load requirements.Build three-dimensional model in SolidWorks and import it into Comsol Multiphysics to complete magnetic circuit simulation analysis.The results show that the optimum design of the locking mechanism and the limited magnetic conductive steel plate is better than that of the non-optimum bearing.when the current is 0.5A,1A and 2A,the average magnetic induction strength of the magnetic sensitive rubbers increases by 71.3%,27.8% and 19.1% respectively.After comparing the simulation results,considering that it is easier to collect the resistance value of magnetic sensitive rubbers in the subsequent self-sensing performance test,three layers of magnetic sensitive rubbers are selected as the optimal model.Then the bearing is processed and assembled,and the modified magnetic sensitive rubbers material with better performance were prepared and installed in the bearing.3.The principle of self-sensing property of magnetic sensitive rubbers is analyzed from three aspects: piezoresistive property,shear property and magnetoresistance property.Two kinds of resistance acquisition methods of steel lead and side lead are designed,and a self-sensing performance test platform is built.In view of the laminated structure of the bearing in this thesis,the method of mixing and collocating laminated magnetic sensitive rubbers with different properties is adopted,and then the self-sensing performance of the bearing under different perception layers is tested and compared.The experimental results show that in the test of piezoresistive characteristics under vertical extrusion load,the change rate of magnetic sensitive rubbers resistance is 30.0%,the maximum hysteresis rate is 21.4%,the stiffness change rate is 16.9%,and the overall perception performance is the best.In the transverse shear load test under different vertical static pressures,the shear resistance characteristics of the middle layer as the sensing layer are also optimal.Then the middle layer is used as the sensing layerto test the self-sensing performance of the bearing by two kinds of resistance acquisition methods,and the repeatability and stability of the sensor characteristics are verified by experiments.Based on the analysis of the experimental results,the rules of bearing stress state are obtained: when the bearing is subjected to dynamic vertical pressure,the resistance of upper and lower ends and side resistance of magnetic sensitive rubbers decrease at the same time;when the bearing is subjected to dynamic transverse shear force,the resistance of upper and lower ends and side resistance of magnetic sensitive rubbers increase at the same time.The experimental results provide data reference for multi-directional vibration protection of magnetic sensitive rubbers bearings.4.Aiming at the vertical controlled vibration isolation of the support,the control circuit is designed,including the overall framework of the hardware circuit,the selection of the main control chip,the magnetic sensitive rubbers resistance detection module,the magnetic field intensity detection module and the coil current control module.According to the hardware circuit,the corresponding control algorithm is designed,including the overall algorithm framework,signal preprocessing algorithm,stress state recognition algorithm and decision control algorithm.On the basis of self-sensing test platform,an experimental platform of controlled vibration isolation system is built to complete the controlled vibration isolation experiment.The results show that the small vibration isolation bearing can self-perceive the real-time vibration state,and use the circuit to make decision and control to complete the controlled vibration isolation.The amplitude of small isolation bearing with control is 36.4%lower than that without control.