Study On Vibration Isolation Performance Of Stewart Platform For Pissive Vibration Isolation

Multidimensional vibration is a common phenomenon of practical engineering.The multidimensional vibration is harmful for the machinery and equipment,and how to Vibration-isolation,especially the vibration of the high precision instrument,is especially important.With the high stiffness,strong carrying capacity,good dynamic characteristics,the Stewart Mechanism are widely used in the body of the multidimensional vibration isolation equipment.The most studies are carried out on active vibration isolation,but its fields of use are limited by its complicated structure,low reliability and energy dependence.So it necessary to have an in-deep study on Stewart Platform for passive vibration isolation applications.Based on the Stewart Platform for passive vibration isolation,dynamic response characteristics,structural parameter optimization etc.and the system has been carried out in the research work.The specific contents and research conclusions are as follows:(1)The impact of structural parameter on natural frequency.The system dynamics model is established by using Newtow-Euler principle,and the natural frequency equation of the vibration isolation platform is deduced.On this basis,the structural parameters of the stiffness and damping coefficient of pod's shock absorber,the radius of the joint on the up-platform,the angle of two neighboring joints on up and down platform,the distance of up and down platform center of mass on the original position is been considered in natural frequency calculation,and then the distribution of six natural frequency under a certain structure parameters range is calculated.(2)Pods' Discretization Modeling Method of Stewart platform and the simulation research.In order to accurately consider the influence of the flexible deformation of the pods and the damping of the kinematic pairs on the vibration isolation performance,a discretization mathematical modeling method of pods is proposed based on the single pod structure model and multiple degree of freedom vibration theory.The“ quality-spring-damper”discretization model of the spherical hinge,pods and hook joint is established and then the model for the kinetics equation modeling of the vibration isolation platform is deduced.(2)The vibration characteristic simulation analysis of vibration isolation platform.By using UG three-dimensional model into ADAMS and ADAMS/Vibration module as Vibration analysis tools,The Vibration Transmissibility for Stewart Platform for passive vibration isolation has been used of performance evaluation index.The simulation results found the system Vibration transmissibility 0.2DT ?,which shows that damping effect is good.In addition,the research has been worked in this paper provides a reference for the design and optimization of the main shaft bearings,which guid significance to engineering application.The modal participation factors and frequency response curve,respectively,has been simulation researched,which found platform on the low order of frequency is high contribute to acceleration response than the high order of frequency.Finally,The mapping Relation of the damping c and spring stiffness k and transmissibility T_D are studied.