Experimental and numerical study on surface roughness of magnetorheological elastomer for controllable friction

Abstract

Magnetorheological elastomer (MRE) is a type of smart material of which mechanical and electrical properties can be reversibly controlled by the magnetic field. In this study, the influence of the magnetic field on the surface roughness of MRE was studied by the microscopic modeling method, and the influence of controllable characteristics of the MRE surface on its friction properties was analyzed by the macroscopic experimental method. First, on the basis of existing studies, an improved mesoscopic model based on magnetomechanical coupling analysis was proposed. The initial surface morphology of MRE was characterized by the W-M fractal function, and the change process of the surface microstructures of MRE, induced by the magnetic interaction between particles, was studied. Then, after analyzing the simulation results, it is found that with the increase in the magnetic field and decrease in the modulus of rubber matrix, the surface of MRE changes more significantly, and the best particle volume fraction is within 7.5%-9%. Furthermore, through experimental observation, it is found that the height of the convex peak on the surface of MRE decreases significantly with the action of the magnetic field, resulting in a reduction in the surface roughness. Consistent with the simulation results, a particle volume fraction of 10% corresponds to a maximum change of 14%. Finally, the macroscopic friction experiment results show that the friction coefficients of MREs with different particle volume fractions all decrease with the decrease in surface roughness under the magnetic field. When the particle volume fraction is 10%, the friction coefficient can decrease by 24.7% under a magnetic field of 400 mT, which is consistent with the trend of surface roughness changes. This shows that the change in surface morphology with the effect of the magnetic field is an important factor in the control of MRE friction properties by magnetic field.

Relationship between Friction Coefficient and Surface Roughness of Stone and Ceramic Floors

“…The rationale of the HPS is to determine the coefficient of friction by dividing the horizontal pull force by the gravity of the weight unit. This is similar to that of the sliding friction tester in the literature [41].…”

Study on Sliding Friction Characteristics of Magnetorheological Elastomer - Copper Pair Affected by Magnetic-Controlled Surface Roughness and Elastic Modulus

“…In general, the change rate of the elastic modulus of MRE under magnetic field is relatively high, which can increase 123% [26]. Although the surface morphology of the MRE is also controlled by the magnetic field to produce changes [24], compared with the changes in the elastic modulus, the range of surface morphology changes is smaller, which only within 30%. Since 1 and 2 are positive constants, the influence degree of elastic modulus is greater than that of surface roughness, so the changing trend of MRE friction force mainly depends on the magnetic-controlled elastic modulus, and the influence of magnetic-controlled surface morphology is relatively small.…”

Study on sliding friction characteristics of magnetorheological elastomer—copper pair affected by magnetic-controlled surface roughness and elastic modulus

“…On this basis, our research group [19,20] derived that there maybe some trend between the friction coefficient of the isotropic MREs and the elastic modulus by combining the elastic contact theory. Meanwhile, our research group [24] found that the surface morphology of the MREs also changed with the magnetic field, and the surface roughness can affect the friction characteristics. In addition to the mechanical properties of the contact surface, the topographical features of the surface and modulus are also important factors affecting the friction characteristics [25].…”