Manufacturing and testing of an optimized Magneto-Rheological (MR) fluid and modelling of a Twin tube MR damper using a modified non-Newtonian model using analytical quasi-static, analytical unsteady, numerical and experimental methods

Magneto-rheological fluids are one of the intelligent fluids which have been extensively used in engineering application including magneto-rheological dampers. Having yield stress in a magnetic field and ability to control and increase their viscosity are their most important characteristics. After three different carbonyl iron powders were subjected to analysis, five different magneto-rheological fluids were synthesized and were tested for stability and the optimized fluid obtained. The results obtained from the optimized magneto-rheological fluid with 85% (weight %) iron powder was similar to that of LORD oil. Also, a modified non-Newtonian rheological model was developed to predict the behavior of the optimized magneto-rheological fluid which is more accurate than Bingham and Herschel-Bulkley models and could be implemented in computational fluid dynamic modelling. The modelling of the damper was conducted by implementing modified non-Newtonian and Bingham models using analytical quasi-static, unsteady and computational fluid dynamicmethods and the results were validated with experimental data. The results show that neglecting factors including fluid shear thinning, wall shear stress and inertia term effects and effect of magnetic field on plastic viscosity in conventional modelling methods results in considerable error that will increase as magnetic field, Reynolds number and gap are increasing.