Papers by Keyword: Magnetorheological Effect

Abstract: This study introduces a sucrose acetate isobutyrate (SAIB) as an additive of magnetorheological elastomers (MREs) to be added in silicone rubber matrix and carbonyl iron particles (CIPs) as their filler. The CIPs were fixed at 60 wt% and two types of MREs sample were fabricated which are isotropic and anisotropic. Rheological properties related to shear storage modulus were measured using a rheometer (MCR 302, Anton Paar). The experimental results demonstrated that the magnetorheological (MR) effect of anisotropic MREs-based Silicone/SAIB was 126 % as compared to isotropic MREs-based Silicone/SAIB, 64%. The fabricated MREs samples were frequency and strain dependent. The relative MR effect for both samples showed decreasing trend with the increment of strain amplitude and excitation frequency.

Abstract: In this paper, the correlation between the particle size and rheological properties of MRE was discussed through both experimental results and theoretical analysis. It shows that the particle size can significantly influence the magnetorheological effect by changing the initial shear modulus and the saturated magnetic-induced shear modulus . With an increase in the particle size, the initial shear modulus gets lower, and the saturated magnetic-induced shear modulus increases to the maximum and then decreases. The larger the particle size is, the longer the distance between neighbor particles along the magnetic field is. Based on the relationship between the particle size and shear modulus, there exists an optimum size for added particles. Moreover, the performance of MRE can be improved by optimizing the particle size based on those rules.

Abstract: The dynamic magnetorheological (MR) effects of 1,5-Naphthalene diisocyanate (NDI) polyurethane-based MR elastomers were tested by changing excitation frequency, excitation amplitude, magnetic strength, or preload. NDI polyurethane-based elastomers show high dynamic mechanical property, and were used as base material to prepare MR elastomers, whose mechanical performance and dynamic MR effect were tested. The results show that: (1) the prepared NDI polyurethane-based MR elastomers have high mechanical performance and MR effect; (2) their MR effect was reduced with the increase in excitation amplitude or preload, but did not change obviously with the increase in excitation frequency. Therefore, MR elastomer devices should be reasonably designed to maximize MR effect.

Abstract: Adopting carbonyl iron powder and silicone/mineral oil as suspend phase and dispersed phase separately,and silica, kaolin as lubricant additives,magnetorheological (MR) fluid was prepared by ball milling. The apparent viscosity of base oil and shear stress were measured on a modified rotational viscometer. The experimental results demonstrated that an appropriate viscosity of base oil contributed to the rheology of MRF. Adding a small amount of thixotropy into MRF had little influence on zero-field viscosity, which facilitated the application of MRF to maintain adequate liquidity. Under low shear rate conditions, the shear stress was improved by adding thixotropy to some extent, especially in the mineral oil-based magnetorheological fluid, in which the role of silica was superior to kaolin.

Abstract: As one of the intelligent materials, Magnetorheological Fluid is dispersions composed of soft magnetic particles, carrier liquid and additives. The apparent yield strength of Magnetorheological Fluid can be changed significantly within milliseconds by the application of an external magnetic field. As the key elements of the three-dimensional imaging, the three-dimensional grating is a special material composed of cylindrical lens. Because water-based magnetorheological fluid has a unique magnetorheological effect, good rheological properties and environment-friendly performance, it is applied to the production of three-dimensional printing grating, through the change of the magnetorheological fluid to control the exact distribution of the soft magnetic particles, so as to achieve the desired accuracy, light transmittance and stability of printing raster, and finally present a ideal three-dimensional effect after laminating the grating and three-dimensional images.

Abstract: The dual characteristic of magnetorheological rheology and phase transitions is studied and its rheological principle is also described. By using the ANSYS finite element method, a simulation analysis of the torque transmission model is conducted. By selecting the magnetorheological fluid SG-MRF2035, a magneto-rheological torque servo device prototype (Gap of 1.5mm) is developed. And a performance testing platform is built for the torque output characteristics of prototype. The test results show that the device could provide supple output torque and the torque is continuously adjustable. This paper provides a new way for the wide application of magnetorheological fluids.

Abstract: Magnetorheological elastomer composites (MREs) based on different magnetoactive fillers such as: carbonyl iron powder (CIP), gamma iron oxide (γ-Fe₂O₃), micro-and nanosize Fe₃O₄ are reported and studied. MREs were obtained from various elastomer matrixes such as: ethylene propylene, acrylonitrile butadiene, silicone, ethylene-octene and polyoctenamer rubbers. To align particles in elastomer, cross-linking process took place in magnetic field. Effect of the amount of ferromagnetic particles and their arrangement on the microstructure and properties in relation to the external magnetic field was examined. The microstructure, magnetic and magnetoreological properties of compositions were investigated with scanning electron microscopy (SEM), vibrating sample magnetometer (VSM) and ARES Rheometer with magnetic device. Cross-linking density and mechanical properties of the composites were also studied. It was found that microstructure anisotropy has significant effect on the properties of magnetorheological elastomers. Moreover, different amount of magnetoactive fillers influence mechanical and magnetic properties of the vulcanizates. Many essential conclusions occur after application the wide variety of elastomer matrixes filled with different ferromagnetic particles in the context of preparation process of smart materials based on magnetorheological elastomer composites.

Abstract: Magnetorheological elastomers are a new kind of MR materials, which consist of magnetizable particles and elastomers. Because of the controllable orheological properties, the materials show a widely prospect in engineering application. In this paper, the magnetic-induced modulus under shear-compression mode was studied. Based on the modulus, the relative MR effect and its influence factor were systematically analyzed. The results show that the relative MR effect will increase with the increasing volume fraction of magnetizable particles, the exterior magnetic field strength and compression strain, and decrease with the increasing shear strain and modulus of matrix. For the study of the relative MR effect, it will give useful advices for the design of MR materials and MR devices.

Abstract: A new tiny-grinding wheel cluster polishing method based on the Magnetorheological (MR) effect is presented to polish optical glass in this paper and some process experiments were conducted to reveal the influence of magnetic field strength, the content of carbonyl iron in the MR fluid and the speed of polishing disc on the material removal rate and the surface roughness of the glass workpiece. The results indicate that when the external magnetic field is applied, the material removal rate of the workpiece improves rapidly but the surface roughness increases slightly. When the Magnetic field strength is 100 Gs and the content of carbonyl iron is 3.5%, the material removal rate improves by a factor of 16.8% compared with that of the conventional polishing methods with dissociative abrasive particles, while the surface roughness of the workpiece increases unobviously.

Abstract: Experiments were conducted to polish optical glass with the magnetorheological (MR) effect-based tiny-grinding wheel cluster, and the influences of abrasive material, particle size and content on the material removal rate and surface roughness are investigated. The experimental results indicate that: the higher the hardness of abrasives, the higher the material removal rate, but the abrasives with lower hardness can obtain lower surface roughness. The better polishing quality of the workpiece can be obtained when the particle size of abrasives is similar to the particle size of magnetic particles. Moreover, the content of abrasives has an optimum value, and the material removal rate and the surface quality can not be improved further when the content of abrasives exceeds the optimum value. On the basis of above, the material removal model of the new planarization polishing technique is presented.