Preparation And Study On Mechanical Properties Of Mr Damping Materials Based On Dry-free Preparation Technology

Magnetorheological(MR)fluids,as a kind of typical intelligent materials,have unique MR effect,and based on which various MR devices,such as MR dampers,MR polishers,and MR clutches,are designed and widely used in civil and military fields,like structural seismic resistance,mechanical engineering,auto industry,aerospace industry,precision instrument processing,etc.At present,domestic and oversea scholars have paid much attention to the research of improving the stability and shear yield stress of MR fluids and establishing a model to accurately describe the mechanical mechanism,and got some significant results.In this paper,the mainly researches of MR fluids from these aspects,which includes preparation technology,performance tests and micromechanical model.From the perspective of improving the preparation process of MR fluids and on the basis of conventional preparation technology,a dry-free preparation technology of MR fluids was proposed,which has been developed from the liquid replacement method.The feasibility and validity of this innovative technology was validated by performance tests.Meanwhile,through a contrastive analysis of influence factor of the performance on the process,the optimum formulation of high-performance MR fluids was confirmed by using control variate method.Moreover,an integrated MR fluids preparation device was designed based on the dry-free preparation technology.In terms of theoretical research,a single-chain micromechanical model considering the influence of adjacent chains was proposed based on the perspective of microscopic chain formation,which was verified by comparing with the experimental values.The research work of this paper covers the following aspects:1)A dry-free preparation technology of MR fluids was proposed to make up the shortcoming of liquid replacement method.Combined with the two key influence elements: magnetic separation technology and the properties of silicone oil/anhydrous ethanol blend,a series of MR fluids samples with different components were prepared by controlling variable method to change the quality of residual anhydrous ethanol in ferromagnetic particles,the mass ratio of silicone oil/ethanol and the amount of additives.2)According to the dry-free preparation process of MR fluids and equipment improved,a new integrated MR fluids preparation device was developed,which effectively combined the functions of ultrasonic dispersion,water bath heating,mechanical stirring,and magnetic absorption separation,to improve the preparation efficiency and mechanical intelligence of MR fluids.3)Through a series of experiments such as the sedimentary stability,zero-field viscosity,viscosity-temperature characteristics,and shear yield stress tests,the factors influencing the properties of MR fluids was experimentally evaluated and the optimum formulation of highperformance MR fluids was confirmed.The feasibility of the dry-free preparation process was demonstrated through comparative experiment with the MR fluids prepared by the traditional preparation method.4)Based on the numerical simulation of the microstructure and morphology of MR fluids,the chain formation mechanism of MR fluids was explored.On this basis,combined with the theory of magnetic dipole and coupling field,a single-chain micromechanical model considering the influence of adjacent chains was established,and the results compare well with previous experimental data and can describe accurately the performance of MR fluids under shear force.The innovation of this paper lies in:1)A new dry-free preparation technology of MR fluids was proposed,which effectively made up for the defects of vacuum drying and mechanical grinding process in the traditional preparation process,and magnetic separation technology was used to complete the separation of ferromagnetic particles from the dispersive medium to improve the separation efficiency.An integrated MR fluids preparation device based on the dry-free preparation process was developed,which realized the multifunctional integration of the preparation sub-process.2)The chain formation mechanism of MR fluids was explored by numerical simulation of the microstructure and morphology.Based on the chaining characteristics,a single chain micromechanical model of MR fluids considering the influence of adjacent chains was systematically proposed,and the theoretical values of model are in consistent with the test results.