Squeeze flow behaviors of magnetorheological plastomers under constant volume

Abstract

The squeeze flow behaviors (including compressive, tensile, and oscillatory squeeze behaviors) of magnetorheological plastomers (MRPs, a kind of solidlike magnetic gels) under different experimental conditions are systematically investigated. Both compression and tension processes can be classified as elastic deformation region, stress relaxation region, and plastic flow region. A squeeze flow equation is used to describe the compressive behaviors of MRP in plastic flow region from which the compressive yield stress can be obtained and compared. The results demonstrate that both compressive yield stress and tensile yield stress are sensitive to magnetic field, particle distribution, and particle concentration. The yield stress of MRP under squeeze flow is larger than that of MR fluids due to the existence of polymer matrix. Asymmetry of hysteresis loop is found under oscillatory squeeze mode. The oscillatory squeeze behaviors of MRP are also influenced by magnetic field and particle concentration, but the influence of particle distribution is not so obvious. The related results under three operational modes are compared and qualitatively analyzed, which are helpful for further understanding the MR mechanism in the solidlike magnetic gels. V

Recent progress on the magnetorheological plastomers

“…It is reported that compressive yield stress and the tensile yield stress are sensitive to the magnetic field, particle concentration, and particle distribution. Because the viscosity of polymer matrix is higher than the silicon oil, the yield stress of the MRP is larger than the relative MRF under the squeeze mode [83]. Moreover, the MRP is a typical soft magnetosensitive polymer composite, so it has a large magneto-deforming effect.…”

“…Besides the normal forces, the squeeze flow behavior of the MRP has also been systematically investigated [82,83]. The elastic deformation region, stress relaxation region, and plastic flow region are presented in the compression and tension testing.…”

Feasibility study of a miniaturized magnetorhological grease timing trigger as safety and arming device for spinning projectile

“…Such locking and unlocking capability of MR-based devices enable us to lower costs, improve reliability and provide a time delay or dampening effect [9]. In addition, the coupling between field-induced structuring and hydrodynamic interaction gives rise to the rich phenomena of MR fluids under squeezed flow [10,11], which significantly favors the tuning of the delay time for triggering the arming of a spinning projectile.…”

Squeeze flow behavior of shear thickening fluid under constant volume

“…Sample will be squeezed out of the plate during the test. In the constant volume mode, the sample radius is smaller than the plate and the radial interface is free [16,17]. Using a constant area parallel plate apparatus, sealing effect is responsible for squeezing out an unknown quantity of particles from the sample between the plates, resulting in the change of particle concentration between the parallel plates [18].…”

“…This form of squeeze is often used for small amplitude vibration dampers [16]. Considering the geometry between STF and plates, two different squeeze modes can be selected: constant area mode and constant volume mode [16][17][18][19]. In the constant area mode, the sample radius gradually grows larger than the plate.…”