Design Of Dynamic Characteristics Adjustable Passive Damper

Recently,along with the rapid development of science and technology,modern machinery tends to the development direction of high-speed,lightweight and precision,and mechanical vibration is an important factor affecting the high speed,light weight and precision of the mechanical development.Vibration isolation is an important means for effective control of mechanical vibration in the process of vibration transmission.The traditional passive vibration isolation can't meet the increasing vibration isolation requirements of the mechanical equipment,and the active vibration isolation control system is complex.The semi-active isolation method combining passive isolation and active isolation becomes a new research hotspot.Based on the comprehensive analysis of the regulation technology of the existing semi-active vibration isolator,a dynamic characteristics adjustable passive damper,which is suitable for different application situations,is designed.Using sound coil motor to simulate the excitation input of the shock absorber,the piezoelectric ceramic is used to adjust the stiffness and resonant frequency of vibration isolation system of shock absorber,and the design of semi-active vibration isolation intelligent shock absorber is studied.Firstly,based on the adjustment principle of the equivalent stiffness and resonant frequency of the prestressed beam,a dynamic characteristics adjustable passive damper is designed,and the working principle of the damper is expounded.According to the design requirements of the tension force distribution as uniform as possible and linearization regulation,the finite element analysis and parameter optimization of the vibration reduction platform,which is the core component of the shock absorber,are combined with the multi physical field coupling simulation software COMSOL Multiphysics and MATLAB.The tension regulation institutions,which is satisfied the design requirements,is obtained,by solving the optimization mathematical model.Determine the size parameters of the shock absorber by using the above optimization design,the stiffness and resonant frequency analysis of the vibration reduction platform are carried out by COMSOL Multiphysics,and the working stiffness and resonant frequency under the action of different tension forces are solved respectively,make a comparison and analysis with the theoretical formula values of the design guidance,get the corresponding adjustment relations.The finite element simulation results show that the maximum relative error of the equivalent stiffness and resonant frequency of the optimized vibration damping platform is 4.44%,and it is linearized to meet the design requirements of the tensioning mechanism.Secondly,dynamic response analysis of vibration isolation characteristics of shock absorber,the corresponding matching relationship between the excitation frequency and the resonant frequency of the vibration isolation system is studied,which provides the basis for the resonant frequency regulation of the subsequent vibration damping performance test.The mathematical model of the vibration system is established according to the simplified dynamic model of the shock absorber structure.The model is simulated in the MATLAB/Simulink environment,and the dynamic response and vibration isolation characteristics of the forced vibration of the damping system are analyzed.Taking the amplitude transfer ratio as the evaluation criterion of vibration isolation effect,the vibration damping effect at different excitation frequencies is analyzed.The dynamic simulation results show that the dynamic characteristics adjustment can make the force transfer ratio shift,effectively realize the good vibration isolation in a certain wide frequency range,and increase the frequency range of the shock absorber.Finally,based on the builted experimental system platform of the shock absorber,the experiment of frequency displacement and vibration reduction performance is carried out.The control scheme of the experiments which are tested the frequency displacement characteristic and damping performance of the shock absorber are designed,test the resonant frequency and corresponding output displacement of the vibration isolation system under different piezoceramic driving voltage,and obtain the frequency displacement characteristic curve,which provides the adjusting range of resonant frequency for the test of damping performance.The experimental results show that the designed dynamic characteristics adjustable passive shock absorber can increase the working bandwidth of the shock absorber.