Physical Mechanisms of Magnetic Field Effects on the Dielectric Function of Hybrid Magnetorheological Suspensions

Abstract

In this paper, we study the electrical properties of new hybrid magnetorheological suspensions (hMRSs) and propose a theoretical model to explain the dependence of the electric capacitance on the iron volumetric fraction, ΦFe, of the dopants and on the external magnetic field. The hMRSs, with dimensions of 30 mm×30 mm×2 mm, were manufactured based on impregnating cotton fabric, during heating, with three solutions of iron microparticles in silicone oil. Flat capacitors based on these hMRSs were then produced. The time variation of the electric capacitance of the capacitors was measured in the presence and absence of a magnetic field, B, in a time interval of 300 s, with Δt=1 s steps. It was shown that for specific values of ΦFe and B, the coupling coefficient between the cotton fibers and the magnetic dipoles had values corresponding to very stable electrical capacitance. Using magnetic dipole approximation, the mechanisms underlying the observed phenomena can be described if the hMRSs are considered continuous media.

Composites Based on Cotton Microfibers Impregnated with Magnetic Liquid for Magneto-Tactile Sensors

“…The induced electrical effects by the magnetic field in the obtained composites are due to the magneto-deformations, as described in refs. [34][35][36]55]. In these references, the electrical response of the devices manufactured using composites based on CI microparticles is sensibly higher, as compared to the electrical devices obtained here.…”

“…Similar effects are reported in Refs. [54,55] and it can be observed from the above equations for the equivalent electrical capacitance and resistance. These also show that fixed values of B and Φ Fe 3 O 4 , the values of A ε and A σ increase linearly with F, as seen from Figures 10b and 10c, and Figures 12b and 12c, respectively.…”

“…It is known that in a gravitational field, and respectively by application of a uniform field of compression forces, the distance between magnetizable particles decreases [54,55]. The net effect is the increase of the equivalent electrical capacitance, and respectively a decrease of the equivalent electrical resistance of ED with increasing the compression forces.…”

Electrorheological and magnetorheological properties of liquid composites based on polypyrrole nanotubes/magnetite nanoparticles

“…This characteristic is distinct from systems involving heavier microparticles, where higher electric field strengths are necessary to achieve a similar effect. For example, [48] highlights how the weight of microparticles, specifically carbonyl iron microparticles, influences the dielectric functions of hybrid magnetorheological suspensions, underscoring the impact of microparticle mass on the behavior of such systems.…”