Theoretical And Experimental Researches On A Viscous Damper

With the fast development of economics, in recent years, various kinds of super high-risebuildings and sea-crossing bridges emerge in large numbers. Due to their special structuresand the surrounding environments, they will damage and collapse easier under earthquake andhurricane. To protect buildings and bridges against earthquake and wind, it is necessary toenhance the aseismatic ability of the structure. Viscous damper, due to its great advantages insecurity, effects, long life, and low cost, is applied in super high-rise buildings and bridgesaround the world as a new seismic design. Native researchers begin to study in this field alittle later, and improvements can be made on the viscous damper’s theory research andstructure research. The Purpose of this paper is to make a further research on the mechanismand internal structure of viscous damper, which will lay a foundation for improvingengineering performance of viscous damper.In this thesis, on the basis of fluid dynamic theories and viscous damper’s specialstructure, three types of damper, an orifice type damper, a clearance type damper and a mixedtype damper, are analyzed. Through the analysis, damping force formulation is built, and anumerical simulation and CFD(calculation fluid dynamic) simulation are made based on theformulation. The results show that different damping structures have influence on the outputdamping force of viscous damper. When the flow area of damping structure keeps the same,the clearance type damper produces the biggest damping force among the three type dampers.It also finds that parameters of the structures of viscous damper, the relative physicalcharacters of fluid medium and working condition of viscous damper all affect the outputdamping force. The amount of the damping orifice and the size of the clearance are twostructure parameters that have the most remarkable influence among other structureparameters. In addition, the kinematic viscosity and flow index of the fluid medium, theamplitude and frequency of the sinusoidal motion of the piston all have certain influence onthe damping force.According to the formulas and the analysis, the prototype of the damper was designedand manufactured. Then performances were tested. Results show that the damping forceincreases while the diameter of the piston becomes larger. However, the energy consumptionof the damper with a38mm wide piston is much more than the damper with a40mm or42mmwide piston. When the clearance keeps the same, the clearance type damper provides a largerdamping force than the mixed type damper, while the energy consumption performance of theformer one is worse than the later one. The relative error analysis is taken on the largestdamping force and the highest pressure in the chamber. Results show that the theoreticalformula can be used to predict the maximum damping force and pressure, which providescertain guides for the practical engineering application.