Study On Vibration Reduction Characteristics And Optimal Model Of Particle Damper

Particle damping technology has great potential for structural vibration control,but at present,when it is applied in engineering,it mostly adopts the method of setting several schemes for a specific problem by experience or analogy method,and then screening the best scheme by means of experiment or simulation analysis.Its efficiency is low,the cost is high,and the design parameters may not reach the optimization.Therefore,in engineering practice,there is an urgent need for a forward optimization design method of particle damper when the natural and vibration characteristics of the controlled structure are known.In view of the urgent needs of this engineering practical application,this thesis studies and solves the forward optimization design problem of particle damper in engineering practical application,which has certain theoretical significance and engineering application value.In this thesis,the cantilever beam is used as the controlled structure,and the experimental bench for studying the particle damper is built.Through the experiment,the effects of particle size,filling rate and particle material on the vibration reduction performance of particle damper are obtained.The stiffness and mass coupling characteristics of the controlled structure and the particle damper are explored,and the interaction relationship between the particle damper and the controlled structure under different vibration accelerations is found.The joint simulation model of cantilever beam with particle damper is established by using ADAMS and EDEM.The simulation results are compared with the experimental results to verify the correctness of the joint simulation method.The main conclusions obtained from the experiment are further confirmed by joint simulation,and the influence law of controlled structure vibration response acceleration and other factors on the vibration damping performance of particle damper is obtained,which provides a basis for establishing the coupling dynamic model of controlled structure and particle damper considering the influence of vibration response intensity.Based on the dynamic characteristics of particle damper obtained from experimental and simulation research and the variation law of equivalent damping,stiffness and mass in the working process,the analytical dynamic model of coupling between controlled structure and particle damper is established,and the design method and process of optimal mass and damping ratio of particle damper based on the coupling model are proposed.The results show that with the increase of the filling rate,the first two modal damping ratios of the cantilever beam increase first and then decrease,and the optimal filling rate is about 70%.Under this filling rate,the two modal damping ratios of the cantilever beam reach the maximum.The higher the density of particles,the better the vibration reduction effect of the two-order modes of the cantilever beam,and the vibration reduction effect of lead ball is better than that of steel ball and aluminum ball.Different particle diameters have different effects on the vibration reduction effect of cantilever beam.The vibration reduction performance of 2mm diameter steel ball with the smallest particle size is better than that of 3～ 6mm diameter steel ball.Under different excitation intensity,the particle damper shows different interaction relationship with the controlled structure: when the excitation acceleration is greater than 1g,the particle damper acts as a damping damper,and the greater the excitation intensity,the better the damping effect.When the excitation acceleration is less than 1g,the particle damper is the additional mass of the controlled structure and does not play the role of vibration reduction,and after the particle damper does not play the role of vibration reduction,the natural frequency of the structure will be reduced;The influence law of different particle filling rate,density and diameter on the vibration damping performance of particle damper obtained by joint simulation is the same as that of experiment,and the larger the elastic modulus of particle is,the larger the damping ratio of the first two modes of cantilever beam is.When the cavity bottom area of particle damper is doubled and two particle dampers are installed,the vibration damping performance of particle damper is better,and the maximum first-order modal damping ratio of the system in these two cases is about twice that when one particle damper is installed.The larger the vibration acceleration is,the more sufficient the particle motion is,and the greater the damping ratio of the first two modes of the controlled structure is.When modeling the coupled vibration system of controlled structure and particle damper,the vibration reduction characteristics of particle damper are considered,which can better describe the interaction between particle damper and controlled structure.The vibration control effect of particle damper on controlled structure is related to the mass and damping ratio of particle damper.In engineering design,the minimum mass and optimal damping ratio of particle damper should be determined according to the maximum amplitude design requirements of controlled structure.In this thesis,the effects of different internal and external factors on the damping performance of particle damper and the damping characteristics of particle damper under different vibration intensity are studied,and the optimization design process and method of particle damper are proposed.The research results can provide reference for the parameter design of particle damper and its parameter design in engineering,and open up a new technical route for further optimizing the design process of particle damper and accelerating its engineering application,It has certain theoretical significance and engineering application guiding value.