Optimization Optimization Optimization of on-State State State ViscostiyViscostiy for or MR Fluid Fluid Fluid Using Anova Approach Using Anova Approach Using Anova Approach Using Anova Approach Using Anova Approach Using Anova Approach Using Anova Approach

摘要

Magneto Rheological (MR) fluids are capable of altering their rheological characteristics like yield stress, viscosity etc. under the influence of applied magnetic field. In the “off” state condition, the MR fluids have the viscosity in the range of 0.1-1.0 Pa-s. Under the presence of magnetic field, their viscosity increases significantly within a few milliseconds resulting in the change of its microstructure from liquid to semi-solid phase. The objective of the present investigation is to develop an optimal combination of constituents of MR fluid which could give high on-state viscosity. For this, an experimental set-up has been developed and designed to magnetize the MR fluid and to determine its on-state viscosity. An L-18 orthogonal array with various input parameters (constituents) affecting the fluid characteristics is designed and used to optimize the on-state viscosity of the MR fluid. It is found that on-state viscosity of MR fluids mainly depends on the volume fraction of the iron particles and type of carrier fluid used in MR fluid formulation. The optimal combination of these input parameters for MR fluid are found to be as Mineral oil with a volume percentage of 67%, iron powder of 300 mesh size with a volume percentage of 32%, oleic acid with a volume percentage of 0.5% and tetra-methyl- ammonium-hydroxide with a volume percentage of 0.7%. This optimal combination of input parameters has given on-state viscosity of 573.094 Pa-s. An experimental confirmation test on the optimized MR fluid sample has been then carried out and the response parameter thus obtained has found matching quite well (less than 1% error) with the numerically obtained values. This research will help the design engineers to fabricate an improved MR based devices mainly for automotive and other sectors.