Magnetorheological dampers with various designs of hybrid magnetic circuits

Abstract

Novel concepts for the magnetic circuit in magnetorheological dampers have been proven. In contrast to the established magnetic circuits where the magnetic field for the control of the magnetorheological fluid is generated by the coil of an electromagnet, hybrid magnetic circuits consisting of at least one permanent or hard magnet and an electromagnet are used in the new approaches. Three different technical configurations are distinguished: (1) The electromagnet is combined with two permanent magnets, whose magnetization cannot be modified even by strong magnetic fields of the electromagnet. The main advantage is the improved fail-safe behavior of the damper in case of a power failure. (2) The electromagnet is combined with a hard magnet, whose magnetization can be modified by the electromagnet. This configuration leads to high energy efficiency, because electric power is only required in short pulses for the switching of the hard magnet. (3) All three types of magnetic field sources, permanent, hard, and electromagnet, are combined in the magnetic circuit, which gives the highest flexibility of the magnetic field generation and the damping control at the expense of a relatively large effort. Demonstrators for magnetorheological dampers with all three magnetic circuits were constructed and their performances were tested. The results of the investigations are described in this paper

Dynamic Model of MR Dampers Based on a Hysteretic Magnetic Circuit

“…Using the time history of the shear yield stress (23) as the bridge connecting the proposed magnetic circuit model and the Bingham fluid based mechanical model (24), the damping forces corresponding to the low-and high-frequency studies in the above section are examined, with the piston velocity chosen as 10 mm/s.…”

“…This makes it possible to conduct more comprehensive studies on the dynamic performances of a MR damper. Moreover, the proposed model can be also applied to the permanent magnets based hybrid-magneticcircuit [23], self-sensing [24], and energy-harvesting [25] MR dampers which receive more and more research interests, because permanent magnets [26,27] can also be accurately characterized by J-A models.…”

ANSYS finite element design of an energy saving magneto-rheological damper with improved dispersion stability

“…The gas of the accumulator would be heated too, which causes extra proliferation of damper stiffness. Many researches have been conducted in controlling the MR damper, whereas only limited analytical and experimental studies have been accomplished on energysaving model and the performance variation of the MR dampers due to thermal effects [26,27]. The concept of hybrid magnetic circuit is a new one, which may be a combination of a permanent magnet (AlNiCo) and an additional coil.…”

Magnetorheological composite materials (MRCMs) for instant and adaptable structural control

“…Application of a magnetic field prompts the suspended magnetic particles to move within the fluid from a relaxed, random distribution and firmly align themselves along the lines of the magnetic flux, which causes an increase in apparent viscosity (Ashour et al 1996). Several potential applications have been identified for these smart fluids, including MR dampers (Böse and Ehrlich 2012) and MR fluid augmented protective fabric (Son and Fahrenthold 2012).…”