Study On Mechanical Properties Of A Spring-STF Viscous Damper

Shear Thickening Fluid(STF)is a non-newtonian Fluid with rheological characteristics.When the Shear rate reaches the critical Shear rate,the viscosity increases rapidly under the influence of Shear stress.This phenomenon of shear thickening was first discovered in industrial production,which also makes the shear thickening fluid attracted wide attention from researchers at home and abroad in human protection,energy dissipation and shock absorption,and other aspects.Viscous damper is a velocity dependent damper,which has good energy dissipation performance and will not provide additional stiffness to the structure.Because of its stable and reliable performance,it is widely used at home and abroad to reinforce the building structure for earthquake resistance and the effect of wind load on the structure.The viscous medium of the viscous damper is a non-newtonian fluid.Under the excitation of the external load,the friction between adjacent flowing layers caused by shear action and the friction generated by the viscous medium through the pores or gaps of the piston provide the damping force.At present,most viscous dampers use silicone oil as the viscous medium,and the viscous dampers using STF as the viscous medium are still in the theoretical and experimental research stage.In this paper,different concentrations of STF are used as viscous media to load the viscous damper under different working conditions,and the influence of its mechanical properties is analyzed.A spring-stf double-bar viscous damper is designed,which is loaded with the same loading scheme,and its mechanical properties are analyzed.Through comparative experiments,the following conclusions are drawn:(1)when the displacement amplitude of STF viscous dampers with concentrations of 10% and 15% is fixed,the maximum output force and energy consumption per cycle of the dampers increase significantly as the loading frequency increases within a certain range,and the energy dissipation performance of the dampers significantly improves.When the loading frequency exceeds a certain range,the maximum output force and energy consumption per cycle of the damper are basically stable.Therefore,the greater the STF concentration is,the better the mechanical properties of the damper are,and the shear thickening effects of 10% and 15%STF are proved from the macroscopic perspective.(2)as the volume of the spring-stf viscous damper is reduced,the maximum output force and energy consumption per cycle are significantly reduced due to the decrease of STF and the decrease of STF when the damper works at a small displacement.When the displacement is large,the maximum output force and energy consumption per cycle of the damper increase rapidly because the STF between the spring reed distance is affected by compression,and the volume of STF working near the piston increases.Therefore,under the influence of small displacement,the mechanical properties of STF viscous damper are better;under the influence of large displacement,the mechanical properties of spring-STF viscous damper are better.(3)the effect of adding spring to the STF viscous damper on the mechanical properties varies with the STF concentration.When the displacement is large,the smaller the viscous medium concentration is,the greater the energy dissipation performance of the viscous damper is improved by the spring.