Magnetorheological damper design to improve vibration mitigation under a volume constraint

Recently, much research has focused on magnetorheological (MR) dampers because of their high reliability, low power requirements, and fast response. When MR dampers are used in a base excited vibration isolation system, large damping forces are used to attenuate resonance below the crossover frequency while low damping forces are required to minimize transmissibility above the crossover frequency. In this study, an MR damper with a bifold valve implemented as an inner bypass (designated as the Magnetorheological Bifold Valve (MRBV) damper) is proposed and fabricated. A theoretical model using finite element analysis is developed, and characteristics are experimentally validated. For comparison, an MR damper with an annular valve implemented in the piston (designated as the Magnetorheological Annular Valve (MRAV) damper) subjected to the constraint that it occupies the same external volume as the MRBV damper, is also analyzed to illustrate the improved performance of the MRBV damper. The performance of these two dampers is then compared in terms of field-off damping force, field-on damping force, equivalent damping and dynamic range. The results show that the MRBV damper can provide lower field-off damping force and larger field-on damping force than the MRAV damper. In order to analyze the advantages of the vibration performance of the MRBV damper, a single-degree-of-freedom isolation system based on the two MR dampers is evaluated. Skyhook vibration control based on the MRBV damper can produce better vibration control performance than a system implemented with the MRAV damper.