A Magnetorheological Damper with Bifold Valves for Shock and Vibration Mitigation

Abstract

This study presents the design and fabrication of a flow-mode bifold magnetorheological (MR) damper for shock and vibration mitigation for high piston velocity (15 mph or 6.75 m/s) as well as an evaluation of its performance at low speed. Based on a Bingham-plastic (BP) model, as well as a BP model coupled with a low speed hysteresis model, two theoretical MR damper models for flow-mode MR dampers are constructed. Using the design strategy associated with the Bingham-model based damper model, two MR damper designs for achieving the performance requirement with a limited space are considered: first, the conventional MR damper that has an MR valve inside the piston head and second, the bifold MR damper that has MR valves at each end of the damper. After numerically comparing the damping performances of the two MR damper designs, the bifold MR damper has been chosen because its dynamic range is better at high speed. The bifold MR damper was tested at a relatively low piston velocity using an MTS testing machine under sinusoidal loading. Experimental data compare well with the results predicted by the theoretical models.

Nondimensional scaling of magnetorheological rotary shear mode devices using the Mason number

“…Magnetorheological energy absorbers (MREAs) have been successfully implemented in semiactive crashworthy systems to protect occupants against impact, shock and blastloads, especially to protect the lumbar region of the human spine [1][2][3]. Shear rates in these MREAs typically range up to 25,000 s À 1 or higher.…”

Measurement of Magnetorheological Fluid Properties at Shear Rates of up to 25 000 s$^{-1}$

“…M AGNETORHEOLOGICAL energy absorbers (MREAs) have been successfully implemented in occupant protection systems to protect occupants against impact, shock and blastloads, especially to protect the lumbar region of the human spine [1]- [3]. Shear rates in these MREAs typically range up to 25 000 s or higher.…”

Control and Analysis of a Magnetorheological Energy Absorber for both Shock and Vibration

“…12 MREAs and the theory of MREAs were only proposed for low-speed applications for a long time, such as vibration con- trol, [13][14][15][16][17] due to their limited damping force performance, especially the dynamic range. 8,11,12 The conventional MREAs with bobbin-in-piston could improve its dynamic range by sacrificing the damping force range, 12 but the efficiency of the magnetic circuit is restricted because of the MR fluid flow gap increment. 18 Bai et al proposed a novel MREA with an internal bypass 11 in order to optimize the damping force performance of the MREA.…”

“…[8][9][10][11] Figure 1 presents the schematic of a semi-active shock and vibration control system based on MR energy absorbers (MREAs). Figure 1 shows that the shock and vibration excitations to the plant, such as commercial-offthe-shelf equipment, occupants on a seat suspension of a helicopter or a ground vehicle, gun recoil, and even the crashworthiness systems, could be mitigated or controlled by using the semi-active control system based on MREAs.…”