Abstract
To optimize the online friction coefficient adjustment, it is necessary to study the parameter change features of the magneto-sensitive polymer and its influence on the friction characteristics under magnetic field. A series of magnetorheological elastomers (MREs) with different initial surface roughness were prepared, and a sliding friction platform with MRE—copper block pair was built to carry out magnetic-controlled friction characteristic experiment. Results show that the sliding friction coefficient of MRE decreases with the increase of the magnetic field, but the degree of reduction is quite different under different initial surface roughness and elastic modulus. When the initial surface roughness of MRE is between 0.5 and 2.5 μm and the carbonyl iron particles volume fraction is between 10% and 15%, its magnetic-controlled friction coefficient has the largest reduced value of 22.75%. Moreover, features of elastic modulus and surface topography under magnetic field were tested and analyzed. By combining with the single peak contact model and the friction binomial law, the relationship between the surface roughness and elastic modulus of MREs and the sliding friction force is deduced, and it is proved that the friction coefficient is affected by the coupling effect of surface roughness and elastic modulus. The magnetic-controlled elastic modulus is the key factor, which determines the overall downward trend of the friction coefficient of MREs. Magnetic-controlled surface roughness also plays an important role in the adjustable range of friction coefficient, and reducing the initial surface roughness can increase the magnetic-controlled friction coefficient adjustable range.
Highlights
Exploring how to control friction and reduce wear has important engineering significance and value [1,2,3]
3.1 magnetorheological elastomers (MREs) sliding friction characteristics test results Using the above-mentioned friction test platform, the prepared MRE samples were measured for surface friction force in positive pressures of 0.95 N, 1.92 N, 2.89 N, 3.86 N, 4.81 N and magnetic fields of 0 mT and 250 mT, respectively
The friction coefficient of MREs before and after application of magnetic field is obtained by Coulomb's law μ = f⁄P, f is friction force and P is positive pressure force
Summary
Exploring how to control friction and reduce wear has important engineering significance and value [1,2,3]. In order to achieve precise control, the sliding friction characteristics of MRE materials and their components in engineering applications, it is necessary to fully understand which factors will affect their friction characteristics after the applied magnetic field. Surface roughness and elastic modulus may not affect friction coefficient alone, and there may be some coupling relationship between the two factors, they are all worth to research and explore. A series of isotropic MRE samples with different initial surface roughness was prepared, and a sliding friction experimental platform was further built. Friction force measurement experiments were performed in the presence or absence of a magnetic field, and the optimal proportions of the MRE with different initial surface roughness were explored, and laid the foundation for revealing the mechanism. Through the application of elastic mechanic equation and tribological equation, one magneticcontrolled sliding friction mechanism of the MREs was revealed, which will help to achieve precisely controllable sliding friction
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