Research Of Vibration Mitigation Performance On Viscous Fluid Damper Filled With Silt And Its Application

Viscous fluid dampers(VFD), mainly composed of viscous fluid and pistons, are widely used in bridges and large scale structures for their simplicity, less auxiliary stiffness provided, and remarkable vibration mitigation performance. After analyzing on traditional dampers, a kind of VFD filled with silt and oil is put forward in this paper. With additional interaction of silt and piston, the maximum output damping force(F) is increased, and more kinetic energy is dissipated. Moreover, the silt can act as a buffer to the piston by limiting its displacement. The silt damper is studied in the paper by theoretical analysis, fluid simulation, dynamic experiment and seismic response analysis.First of all, the CFD method is used to simulate the vibrated fluid, by which the curves of F and displacement(d) can be drawn through the pressure field, then the factors that influence the values of F and dissipated energy are discussed theoretically. Secondly, the dynamic test is designed and conducted, by which the factors is discussed experimentally. Then the scheme to increase the dissipated energy is proposed. Meanwhile, the fitted curves of viscous force(F1) and velocity(v), hysteretic force(F2) and d are obtained. At last, the vibration mitigation performance of the silt damper is evaluated according to the seismic response analysis.Through above studies, the conclusions below are drawn:①The simulation results shows that the energy dissipation model of the dampers with pure oil filled is very close to the linear model, when damper is at a lower velocity. The stiffness of the damper will occur as the velocity increases, which means the energy dissipation model is close to the Kelvin model. Higher grade oil with better viscosity used, larger value of the damping force gotten. Decreases of the number of the piston’s holes and holes’ size could both increase F.②The dynamic test shows that the addition of silt can increase F. A smaller effective stress value is gotten with a shorter displacement, and the F-v curve is in an oval shape. Oppositely, a larger effective stress value is accompanied by a larger displacement, meanwhile, the curve has a rising trend, which means the damping force contains F1 and F2. F1 is v-related, while F2 is d-related.③ The time history analysis shows that the dampers designed and made in experiment could play some roles in vibration mitigation.