Effect of temperature on sedimentation stability and flow characteristics of magnetorheological fluids with damper as the performance analyser

dimentation stability and high yield stress of a magnetorheological fluid (MRFs) are essential parameters for better damping performance for any practical application. Preliminary investigations have been carried out on carbonyl iron particles to determine the morphology, particle size, crystal structure, and saturation magnetization for their feasibility of synthesizing magnetorheological fluids in-house. This study synthesizes various MRFs from various commonly used carrier oils and additives. The MRF samples were prepared for 25% volume fractions of carbonyl iron (CI) powder in either silicone oil (350cSt) or hydraulic oil (50cSt) and by using lithium and calcium-based additives or a combination of both the additives. The sedimentation stability and yield behaviour at different temperatures show a remarkable drop in sedimentation rate and yield stress for all the MR fluid samples. The characterization of the prepared MR fluids reveals that MRF-1, MRF-3, MRF-5 are more stable and have high yield stress values. MRF-1 is selected to further characterize its dynamic performance in magnetorheological damper fabricated based on geometric dimensions obtained from the response surface optimization technique. The results indicate a 164.45% and 135.48% increase in damping force at higher amplitude and higher frequencies at 0A and 1A currents. Further, similar tests have been carried out by synthesizing MRF-7 with silicone oil (50cSt) + lithium base grease as the additive. The sample's stability and yield stress with temperature are carried out, and performance analysis shows a remarkable change in damping force than MRF-1. The dynamic range obtained is practically viable in MRF-7 than MRF-1, with less variability. Finally, temperature characteristics captured from the thermocouple of the MR damper reveal that an average of 43.78% reduction in damping force when the temperature is increased by 19.5 C with increased dynamic range.