Theoretical And Experimental Research On Mechanism Of A Novel Impact Damper With Fine Particles As Damping Agent

Conventional impact dampers feature momemtum exchange and friction, in whichmost of the kinetic energy cannot be exhausted, but reverberated among impact partners.To overcome the shortcoming, this paper proposes a novel impact damper mechanismnamed the theory on impact damper with fine particles as damping agent (IDFPDA),which introduces plastic deformation of fine particles as irreversible energy dissipation.The primary mechanism of IDFPDA is the plastic deformation or even rupture of fineparticles causd by the collision of steel balls in the vibration process, which leads to aperpetual vibration energy dissipation. Intensive study on the performance of IDFPDAhas significant original values in theory innovation and bright prospects in structurevibration control. So this paper emphasizes the theoretical modelling and experimentalstudy on the IDFPDA.This paper firstly proposes a theoretical model of elasto-plastic impact between twospheres to obtain the analytical solutions to velocities of two spheres after impact,effective coefficient of restitution and energy loss factor in an impact period. At thesame time, this paper simulates elasto-plastic impact process between two spheres bymeans of finite element analysis, and the results from finite element analysis are inaccordance with those from the theoretical model. On the basis of the above theoreticalmodel, this paper further builds an estimation model of impact between two sphereswith fine particles to obtain the analytical solutions to velocities of two spheres afterimpact, effective coefficient of restitution and energy loss factor in an impact period. Atthe meantime, relevent results from finite element analysis are in agreement with thosefrom the estimation model. Applicable scope of the estimation model and the effects ofdiameter ratio of fine particle to ball, material and particle amount on the energydissipation in an impact are also discussed.Based on the above two models, this paper sets up an analysis model for acantilevered beam to predict its response when damped by IDFPDA. In the meanwhileof theoretical modelling, the characteristics of free and forced vibration of thecantilevered beam damped by no damper, single unit impact damper, particle damperand IDFPDA are respectively tested. The good agreement between the results fromexperiments and those from theoretical calculation verifies the proposed theoreticalmodels of IDFPDA, which can provide reference to engineering design. On the otherhand, the influences of the volumetric packing ratio, material and diameter of fine particles on the performance of IDFPDA are also studied by experiments, and theexperimental results indicate that the performance of IDFPDA is much more excellentthan that of conventional impact dampers. In the last section, this paper simulates andanalyzes the effects of main configuration parameters on the performance of IDFPDA,including damper clearance, particle yield strength and mass ratio of steel sphere toprimary system, to provide a theoretical foundation for the optimal design of IDFPDA.The main innovations in this paper are listed as follows:1. For the first time we build the theoretical analysis models of IDFPDA whichintroduces the plastic deformation of fine particles as the mechanism of energydissipation. The innovations consist in both the theoretical model of elasto-plasticimpact between two spheres and the estimation model of impact between twospheres with fine particles.2. For the first time we quantitatively discuss the reason that the performance ofIDFPDA is much more excellent than that of conventional dampers, and provide theapplicable scope of IDFPDA. We also study the effects of the diameter ratio ofparticle to ball, material and diameter of particles on the performance of IDFPDA.