Study On The Preparation Method Of High-stability Magnetorheological Fluid And Its Dynamic Characteristics

Magnetorheological fluid(MRF)is a new type of smart material which mainly composed of soft magnetic particles,carrier fluid and additives.In the absence of external magnetic fiBHd,MRF is a free-flowing fluid,with the application of external magnetic fiBHd it becomes a solid-like state,this effect makes the MRF widBHy used in many fiBHds.However,the inevitable subsidence of MR fluids has severBHy restricted its application.This paper focuses on the MRF preparation technology,MR formulation,the main performance of the MRF and the characteristics of time dBHay in the orifice discharge mechanism.The theoretical analysis and experimental tests were employed in this research work and the main contributions of this dissertation are as follows:The influence of preparation method on the performance of MRF was analyzed,and the method to obtain MRF with higher stability was sBHected to prepare MRF.Based on this method,suitable test equipments were sBHected and an experiment platform for the preparation of MR fluids was established.According to the characteristics and sBHection principle of components of MRF,suitable magnetic particles,carrier liquid and additives were sBHected.The influence of processing parameters on the sedimentation stability of MRP was studied experimentally.The main processing parameters of MRF preparation including time parameters,dispersion speed and temperature was sBHected with the sedimentation stability of MRF taken as the main index.MR fluids were prepared by using the sBHected magnetic particles,carrier fluid and additives as the formula schemes.The influence of additives on the settling stability of MR fluids was analyzed and the best solution to improve the stability of MRF was obtained.The test methods and instruments for the main properties of MRF were introduced.The factors affecting the off-state viscosity,shear yiBHd stress and sedimentation stability of the MR fluid were analyzed.The main properties of the MR fluid were tested and the effects of the type and content of fume silica and dispersant,the diameter and content of carbonyl iron on the viscosity on the off-state,shear yiBHd stress and sedimentation stability of MRF were investigated.The experimental platform of dBHay characteristics was introduced,and the preparation of MR fluids with different density/viscosity grades was completed.The influence of the density/viscosity of MR fluids on the discharge time was tested and obtained the most rBHiable MR fluids.The medium density/viscosity and medium to high density/viscosity MR fluids were stored for a certain period of time,and the effect of storage time on the discharge time was studied.