Development of laboratory class experiment to characterize magneto-rheological fluid

Abstract

An experimental apparatus has been developed that characterizes magneto-rheological (MR) fluid for an MIT Mechanical Engineering laboratory class by charting the fluid's yield stress versus magnetic field strength. The apparatus consists of a cantilevered beam that is damped using MR fluid, through which a magnetic field is varied. Unique functional requirements for a class experiment as well as experimental design rationale are also discussed. Lord's MRF-336AG MR fluid is characterized at low magnetic field strengths and compared to the company provided data. Experimental data suggest the magnetic field strength affects the fluid yield stress more greatly than the company data, though both data show similar general trends. This discrepancy likely comes from approximations for damper velocity made in the analysis. Both a Bingham plastic and Newtonian model are used to describe the fluid and based on the similarity of the results from both models at low field strengths, it is concluded that MR fluid can be modeled as a Newtonian fluid for field strengths between 0 and 4 kAmp/m.