| Isolators are designed to connect a vibrating source and a suppported structure and isolate vibrations from one to the other.Many types of isolators,from passive to active,have been developed to be used in various applications such as vehicles,ships,optical devices,and high-precision machines.In order to guarantee the vibration-sensitive devices that need high-performance isolation for proper working conditions under wide frequency range disturbance environments,the hybrid isolators are used to isolate vibrating source and supported structure.Generally,the hybrid isolators have been composed of the active actuator and the passive isolators in parallel or in series,in this way,all the advantages of them can be fully played.In this paper,the hybrid isolator is deeply studied,the theory of the hybrid isolator is analyzed and the sample isolator is designed and obtained,and the validity of the isolator is verified by experiment.The main work is summarized as follows:Firstly,the dynamic model of the inertia-type piezostack actuator is established based on the performance parameters of the piezoelectric material and the influnec of the main parameters of the inertia-type piezostack actuator on its force output is revealed and it provides a theoretical basis on the reasonable design of the isolator.Simulation results show that increasing the inertial mass,the thickness can increase its force output.The static and dynamic characteristics of the piezostack are simulated by using the FEA software ANSYS and the results show that the single-layer piezoelectric plate can produce displacement signal of the same frequency by the sinusoidal voltage signal;the displacement output of the singal-layer piezoelectric plate is linear with applied voltage and force load;the thinner the piezoelectric plate,the larger the cross-sectional area,the bigger the stiffness of the piezostack;the displacement output of multilayer is less than the theoretical output because of the deformation of the adhesice layer.After completion of the theoretical analysis of the hybrid isolator,the auxiliary components design and process,the hybrid isolator has been assembled.By using the half-power bandwidth method,the dynamic characteistics of the piezostack and rubber element can be experimentally evaluated.Then the actuating force experiment was carried out.From the experimental results,the actuating force is linear with the drive voltage at the same frequency and the force is linear with the square of the driving frequency at the same voltage.The passive characteristic of the hybrid isolator is verified by using the Vibration Level Difference after the experiment mounting is established.The experimental results show that this isolator has good isolation performance under high frequency excitation(75Hz-115Hz).Finally,the hybrid isolation system model is built by using Simulink.The active control experiment is carried out by using x-LMS algorrthm.The results show that the vibration reduced about 25 dB and 38 dB under two different force with single frequency 80 Hz and 90 Hz,the isolation performance of the hybrid isolator has been verified. |
