Theory And Characteristics Study Of Viscous Fluid Damper With Compressible Fluid

Viscous fluid dampers is a kind of absorber device. While structures arevibrating, it would protect structure from being destroyed by dissipatingvibration energy, mitigating dynamic response near the resonant frequency,decreasing force and deformation on the nodes. Usually, people consider thatviscous fluid is incompressible, utilizing it without taking its additionalstiffness into consideration. Nevertheless, additional stiffness affects viscousdampers property seriously under certain conditions because viscous fluid iscompressible. And the affection is worse after air mixing into the damper. Soit is necessary for us to study the theory and properties of viscous damperswith compressible fluid. This essay established reasonable theory and logicalprocedures of design with compressible fluid, and discussed its dynamiccharacteristics depending on various experiments.(1) Set purpose for research. It includes the dampering force theory andresearch on the dynamic characteristics of viscous dampers.(2) Viscous dampers is classified into many types by structure. Thehydraulic orifice-type viscous dampers is eventually selected because of itsfine performance and widely application. Viscous fluid viscosity is changedwith shearing rate, temperature and pressure regularly.Besides, the compressibility of fluid contributes additional stiffness toviscous dampers.(3) Viscous dampers exhibits a damper characteristic, as well as ahysteresis behavior which is explained by additional stiffness. However,present study about the additional stiffness is almost upon experimental data,and none make a deeply research in the damper mixed with air. Therefore, calculating the nonlinear dampering force of viscous dampers with severalsame orifices basing on the hydraulic principle, and the dynamic stiffness isalso calculated.Equivalence dampering coefficient is obtained according to theequivalence principle of dissipation energy, and the coefficient can be usedin design.Linear Dampering coefficient and stiffness in series are obtained withthe energy equivalence principle. Then a linear model in parallel which isconvenient in practical application is established basing on them.(4) Design and Manufacture a test-bed basing on the experimentalfunction requirements.(5) Experiment on viscous dampers with a lot of fluid and orificediameters under a special frequency range. These experiments prove thetheories in this essay, and some factors affecting viscous dampers arestudeid.(6) Introduce the application of the theories and consequences. Putforward a new way in viscous damper design, and establish a model formwhich we can estimate the influence of additional stiffness conveniently.