Structural Analysis And Performance Test Of Active Vibration Isolation Based On Combined Positive And Negative Stiffness

The passive structure with positive and negative stiffness parallel active vibration isolator studied in this thesis has excellent characteristics of high bearing capacity and low natural frequency.Combined with active control technology,the active vibration reduction performance of ultra-low frequency can be achieved.In this thesis,the structure of positive and negative stiffness parallel active vibration isolator is analyzed and tested.The main research contents are as follows:According to the design requirement of active vibration isolator,the principle scheme is designed according to the mechanical structure part and the control hardware part.The parameters of the parallel mechanism with positive and negative stiffness in vertical and horizontal directions are designed and the overall structure of the control hardware is preliminarily designed.The three-dimensional structural model of the active shock absorber is determined.The static model of magnetic ring offset and magnetic force in annular permanent magnet structure is established by using the equivalent magnetic charge method.The static model is a four-integral analytical formula,which is calculated by Matlab after adding design parameters.Ansoft Maxwell electromagnetic analysis software was used to simulate and verify the static model established.The results showed that: The calculated value of the static analytical model in this thesis is consistent with the simulation value of Ansoft Maxwell,and the error meets the engineering requirements.Using Ansoft Maxwell simulation,the relationship between the gap Angle ? and magnetic error of fan-shaped magnets was obtained,which provided an important reference for the later design of annular permanent magnet structure.Due to the effect of magnetic force increased the difficulty of structural assembly,the corresponding assembling fixture is designed for the inner and outer magnetic rings.This thesis analyzes the assembly and structural reliability of the active vibration isolator.The assembly dimension chain method and finite element method are used to optimize the structures with insufficient reliability,such as horizontal limit mechanism and roof structure.For structures with large strength and deformation margin,such as the central platform,Design Exploration in ANSYS Workbench is used to carry out size optimization.The optimal design mathematical model of the central platform is established.The response surface optimization method is adopted to simplify the structure of the central platform under the condition that the strength and deformation of the central platform meet the actual engineering application.The whole assembly fixture of the active vibration isolator was designed,and the test platform of the active vibration isolator was built.The passive transmissibility test and damping rate test of the active vibration isolator are carried out on the test platform,and the actual values of natural frequency,stiffness and damping rate of the vertical and horizontal structures of the active vibration isolator are obtained through the test,and the passive structure characteristics of ultra-low frequency vibration reduction are verified.