Magnetorheological (MR) Damping for Vibration Mitigation: Experimental Analysis

Magnetorheological (MR) dampers have emerged as a viable means of semi-active damping in multiple industry applications. The semi-active nature of these dampers is a significant attribute since the damper functions as a passive damper in the event of a failure. While there have been other smart materials like ferroelectric, piezoelectric, shape memory alloys, etc. that have been successfully used, MR fluids exhibit a unique combination of completely reversible effect, very low response time, high durability and very low energy requirements that make them suitable for vibration control in a wide variety of applications. This paper presents results from an experimental investigation that has been carried out to evaluate the performance of a MR damper for vibration mitigation. The capability of a commercial MR damper to isolate a payload from base excitation is analyzed and the damper parameters are identified to simulate the capability of the damper with regards to transmissibility. Multiple iterations of testing are performed in order to evaluate the influence of variables such as input current to the electromagnet, mass of the payload, excitation frequency and excitation amplitude. Results indicate that the MR damper is successful in mitigating vibrations transmitted to the payload. Vibration mitigation is quantified through multiple means such as comparing the root mean square (RMS) of the time history of acceleration of the base with that of the payload, comparing the frequency response and evaluating the hysteresis plots. Displacement transmissibility results directly demonstrate the variable damping capability of the MR damper. Although the stiffness constant of the damper may also change, it is not seen to vary appreciably in this study since the excitation amplitude is limited to a low threshold. The damper is found to be robust with an inherent ability of handling payload and excitation variability. It is observed that increasing the input current to the electromagnet around the MR fluid results in an increase in damping, therefore, making the use of these dampers viable in applications where payloads and excitation inputs are expected to change during operation.