Abstract
Traditional magnetorheological (MR) damper featuring fixed gaps has the shortcomings of small damping force, single dynamic performance, and low adaptability. To overcome these shortcomings, a new MR damper with enhanced effective gap lengths is developed in this work, which achieves a double extension of the effective gap lengths via compactly integrating the conical fluid channels into the annular fluid channels. On the other hand, by altering the axial position of the valve spool controlled by a locking nut, the relative distance between the valve spool and piston of the MR damper is flexibly regulated; thus, the width of this adjustable gap in the conical fluid channels can be continuously adjusted. The magnetic circuit of the proposed MR damper is developed and its mechanical model is established as well to evaluate the dynamic performance. Sequentially, the finite element analysis (FEA) methodology is applied by using ANSYS/Emag software to investigate the changes of magnetic flux densities in these adjustable gaps. Moreover, a prototype is manufactured and experimental tests are conducted to verify its dynamic performance. The experimental results, under a fixed applied current, indicate that the damping force decreases with the increase of the adjustable gaps, and the maximum damping force reaches 7.2 kN at the adjustable gap of 0.6 mm. Besides, the dynamic range increases with the increase of the adjustable gap, and the dynamic range appears with a peak of 13.6. In addition, the damping force varies from 0.2 kN to 7.2 kN while the dynamic range attains 33 correspondingly by regulating the applied current and adjustable gap from 1.6 mm to 0.6 mm. From an experimental results perspective, the damping force and dynamic range can be not only effectively controlled by excitation current but also flexibly altered by regulating the width of the adjustable gaps simultaneously. Therefore, the dynamic performance of the proposed MR damper is also enhanced.
Highlights
MR fluid is a smart material that mainly comprises carbonyl iron particles, carrier liquid, and some additives in a specific proportion [1]
The above methods to improve the dynamic performance of MR dampers primarily include: extending the MR fluid channels, changing the piston structures, optimizing magnetic circuits, and increasing the number of coils
The proposed MR damper with enhanced effective gap lengths can alter the relative position between the valve spool and piston by adjusting the locking nut; the gap in the conical fluid channels can be continuously adjusted
Summary
MR fluid is a smart material that mainly comprises carbonyl iron particles, carrier liquid, and some additives in a specific proportion [1]. The above methods to improve the dynamic performance of MR dampers primarily include: extending the MR fluid channels, changing the piston structures, optimizing magnetic circuits, and increasing the number of coils. Though the multi coils achieve the extension of effective length that magnetic flux lines pass through, the axial dimension of VRG-MMD is inevitably increased and the variable resistance gap is only changed by the motion of piston rod but not flexibly adjusted according to the damping force requirement. The proposed MR damper doubly extends the effective gap lengths and is capable of continuously regulating these adjustable gaps in the conical fluid channels, significantly enhancing the dynamic performance of the proposed MR damper.
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