Piezoelectric Inertial Actuator Based On Magnetorheological Fluid Control

In order to solve the problems of difficult control and poor stability of the piezoelectric inertial actuator,this thesis proposes a method combining the two smart materials(piezoelectric ceramic/magnetorheological fluid).The control unit is composed of permanent magnet and magnetorheological fluid,and a piezoelectric inertia actuator based on magnetorheological fluid control is drove by ends-fixed asymmetrically clamped piezoelectric bimorph.The proposed actuator is systematically studied from three aspects: theoretical,modeling,experimental verification.The static and dynamic characteristics of the vibrator,yoke and actuator are analyzed,and the key design parameters are simulated.The mathematical model is established and the performances are tested of the proposed actuator.1.Analysis and research of piezoelectric bimorph vibratorThe finite element analysis of the influencing factors of the dynamic displacement of the fixed-end piezoelectric vibrator at both ends is carried out.The analysis results show that the dynamic displacement of the vibrator in the direction of the long clamping side and the short clamping side increases with the clamping difference increase.The dynamic test of the fixed-end piezoelectric vibrator at both ends is carried out by the vibration test system.The test results show that the central deformation of the fixedend piezoelectric vibrator increases with the increase of the clamping difference.2.Analysis and research of yokeThe influencing factors affecting the magnetic field distribution between the teeth of the yoke structure,and two key factors are verified by finite element simulation.The simulation results show that the magnetic field distribution between the yoke teeth is closely related to the magnetic field strength of the permanent magnet and the facing area of the permanent magnet and the yoke.Experiments were carried out to test the influence of the diameter of the shearing needle,the positive facing area of the permanent magnet and the yoke on the magnetic field between the yokes,and the reasonable diameter of the shearing needle is determined.3.Structural design and theoretical analysis of the actuatorThe whole structure of the actuator is designed,the working mechanism is analyzed,and the matching relationship between inertial impact and friction is discussed.According to the designed structure of the actuator and the principle of inertial impact/friction operation,the actuator is theoretically modeled based on the Work-Energy Theorem.The timing superposition method is used to calculate the motion state of the actuator at the limit position,and the expression of the output step of the actuator is obtained.4.Experiments of the proposed actuatorThe experimental test system is built and the performance test of the actuator is carried out.The experimental results show that the resolution can reach 0.0204 ?m under the excitation of 2.5 V,45 Hz square wave electric signal;The resolution curve of the experimental result test is in the same condition as the theoretical model,the calculation results are in good agreement;The driving performance is tested,and the maximum load capacity can reach 800 g;The actuator has good repeatability and reliability.After comparing the actuator with or without control structure,the controlled actuator can effectively improve the output performance.