فهرست مطالب yahya rabbani

Industries are severely needed to the promising capabilities of magnetorheological fluids. In most systems that need to regulate the motion by the viscosity change, there is always a solution based on Magnetorheology, resulting in improved performance and cost. The unique properties such as fast response, simple relationship between electrical power and output mechanical power, controllability, and easy and smart performance, have made these fluids a desirable technology for use in vehicle suspension systems. A suitable magnetorheological fluid for use in a vehicle suspension system should have features such as low viscosity in the absence of a magnetic field, promising rheological properties, and fast response in the range of a few milliseconds, good stability against temperature changes and settling and non-abrasive. Also, one of the most important characteristics of a suitable magnetorheological fluid for use in the smart damper is it’s durability against in-use thickening (IUT). It means that in some of the industrial magnetorheological fluids in successive cycles of operation, some parts of the magnetizable particles and also the formed oxide layer on the surface of particles settle and form a hard cake that greatly reduces the effectiveness of the fluid. With a proper selection of materials and synthesis methods, the durability of the fluid in successive cycles can greatly improve. Materials and production methods of magnetorheological fluid should be selected in such a way that the above-mentioned properties are present in the sample for industrial applications.

Magnetorheological fluid is a suspension of magnetizable particles in a base liquid with stabilizer. The rheological properties of these fluids change significantly in the presence of magnetic field. In this study, nanomagnetic iron oxide particles were prepared by using co-precipitation method. X-ray diffraction and scanning electron transmission methods were used to characterize these particles. The magnetic properties of the particles were measured by using a Vibrator Sample Magnetometer. The sedimentation rate for a non-additive fluid was reported to be 70% and when the cellulose was added, it was reported to be 55%. The effect of samples contained nanoparticles iron core shell in various percentages of 0.5, 1 and 2% of nanoparticles with 3% cellulose were investigated. The results showed that almost all of the samples were completely stable after addition of the nanoparticles in the first three days. The results showed that the sample containing 5% by weight of cellulose and 1% by weight of nanoparticle core shell by cellulose had a high stability during more than a month. The increase in shear stress and yield stress in the optimized sample containing the nanoparticle was also significantly higher than the sample without any additive and it was about 10,000 Pasca.