The Damping Algorithm And Design Of Valve-type Low Index Viscous Damper

Hydraulic viscous damper is a kind of vibration and energy dissipation device,which can protect the structure by installing in the building,improve its wind resistance and seismic resistance ability,and is widely used in the engineering field.For different engineering situations,different types of viscous dampers need to be used.The commonly used speed index range of the damper is 0.3-1.0.The lower the speed index is,the wider the working speed range of the damper is,and the stronger the energy dissipation capacity is.In this paper,the hydraulic viscous damper with a speed index of 0.3 is studied by theoretical analysis and experimental testing.At present,the viscous damper damping medium often choose dimethyl silicone oil,belongs to the typical shear thinning fluid,the dynamic viscosity decrease with the increase of shear rate is nonlinear,so the damper damping loss also shows strong nonlinear with the piston velocity,which makes the precise rate of viscous dampers load properties has become extremely difficult.In order to calculate the pressure loss caused by the working medium flowing through the damping hole,the formula for calculating the pressure loss of the damping hole was established based on Bernoulli equation and combined with the shear thinning effect of dimethylsilicon oil.By comparing the experimental results,it is found that the relative error between theoretical analysis and experimental results is basically maintained within ± 10%(lower than ± 15% stipulated by industry standards),which verifies the correctness of theoretical analysis method..Adopts the structure of overflow valve and damping hole series,according to the damping loss calculation formula,designed the two regulating valve type damper,analysis of experimental data,the hysteresis curve of the two kinds of damper are "sharp point" phenomenon exists,analyzes believed that for low frequency,low damping force,piston movement the conversion process of dynamic friction static friction force is the main cause of "sharp point";For the case of high frequency and large damping force,the opening adjustment process of overflow valve is the main reason leading to the "sharp point".By comparing and analyzing the experimental results of regulating valve damper,the experimental value at high frequency is higher than the theoretical value,which is believed to be caused by the dynamic stiffness caused by the compressibility ofoil.MaxWell model was adopted to simplify the calculation formula of dynamic stiffness of oil.After quantitative analysis of pure hole damper and regulating valve damper,it was found that the regulating valve damper could significantly reduce the phenomenon of velocity-load curve deflection caused by dynamic stiffness of oil.This paper studies the energy dissipation mechanism of the damper,and obtains the calculation method of the damping loss of the shear dilute fluid in the damping hole through theoretical analysis.