Compressions of magnetorheological fluids under instantaneous magnetic field and constant area

Abstract

Compressions of magnetorheological (MR) fluids have been carried out under instantaneous magnetic fields. The yield strength of the MR fluid in compressive mode has been derived by assuming that it was a transformed shear flow in Bi-visous model. The compressive stresses have experimentally studied under different magnetic fields, different initial gap distances and different compressive velocities. The nominal yield shear stresses of the compressed MR fluid under different influential factors have been calculated. The compressive stress increased in a power law as the applied magnetic field increased, while it decreased as the initial gap distance and the compressive velocity increased. With the increase of magnetic field, the difference between the nominal yield shear stress curves increased, and the exponents of the power law increased with the increase of the magnetic field strengths. A larger initial gap distance and a lower compressive velocity resulted in a higher nominal yield shear stress under the same instantaneous magnetic field. The achieved results of the nominal yield shear stress with magnetic field seemed to deviate from the prediction of dipole model, and the chain structure aggregation effect, the sealing effect and the friction effect by compression should be considered.

An experimental study on mechanical properties of a magnetorheological fluid under slow compression

“…A sketch of compressing MR fluid between two parallel plates is shown Figure 10. Because the surface morphology of MR particles is usually rough (Covey and Stanmore, 1981; Gartling and Phan-Thien, 1984; Wang et al, 2021b), it will provide the basic strong friction between particles. Zhang et al have proposed a semiempirical model and found that the proposed model is compatible with the traditional dipole model when d / R >> 2 ( R is the radius of the particle and d is the distance between two particles), namely, the particles are not closed (Zhang et al, 2004).…”

Approaches on Ferrofluid Synthesis and Applications: Current Status and Future Perspectives

“…These spikes are highly ordered self-organized structures. Furthermore, it has been reported that a ferrofluid placed under a magnetic field for over 35 years has kept its liquid state with no sign of sedimentation, showing the particular pattern of spikes and meaningful stability (Figure b) …”

“…Furthermore, it has been reported that a ferrofluid placed under a magnetic field for over 35 years has kept its liquid state with no sign of sedimentation, showing the particular pattern of spikes and meaningful stability (Figure 1b). 14 Research in ferrofluid synthesis has considerably increased in the past 50 years. While a large number of research articles published in the early years might not be available online, there has been a large increase in publications in the last 20 years.…”

“…Characteristic pattern of spikes of a (A) MR fluid and (B) ferrofluid under a magnetic field. Photograph A: courtesy of Wang et al (free domain). Copyright 2021, Wang, H.; Bi, C.; Zhang, Y.; Zhang, L.; Zhou, F. Photograph B: courtesy of Priyananda, et al Copyright 2018, American Chemical Society.…”

Influence of Magnetic Field on Sound Transmission Loss of the Unit Filled with Magnetorheological Fluid

“…They exhibit a low viscosity of Newtonian fluids in the absence of magnetic fields and a high viscosity and low fluidity of Bingham fluids under magnetic fields. Moreover, the transition response between their fluid- and solid-like states is quick, and this transition process is reversible [ 3 , 4 ]. Given these advantages, MRFs have been applied in many engineering fields, such as polishing [ 5 ], sealing [ 6 ], braking [ 7 ], vibration control [ 8 , 9 ], etc.…”