Dual Hysteresis Model of MR Dampers

Janusz Gołdasz,Łukasz Jastrzębski,Michal Kubik,Bogdan Sapiński

doi:10.3389/fmats.2020.00236

Janusz Gołdasz, Łukasz Jastrzębski + Show 2 more

Open Access

https://doi.org/10.3389/fmats.2020.00236

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Abstract

This study concerns modeling the hysteretic behaviour of magnetorheological (MR) dampers. In general, hysteresis is one of key factors influencing the output of such actuators. So far more attention of various researchers has been paid to studying the combined hysteretic behaviour of MR actuators by observing the relationships between the output (force/torque) and the inputs (current, velocity, position). However, these devices feature two distinct hysteretic mechanisms: mechanical/hydraulic and magnetic. The mechanical hysteresis is of different nature than the magnetic hysteresis due to the properties of ferromagnetic materials forming the actuator's elec- tromagnet circuit, and these should be split in the modeling process. In the present study we separate the magnetic hysteresis from the mechanical/hydraulic one by investigating the magnetic flux vs exciting current relationship of a commercial flow-mode MR damper subjected to sinusoidal current loading and independently of the mechanical excitations. The resulting behaviour of the electromagnetic circuit is then examined using the nonlinear inductor approach with hysteresis. Total hysteresis is then modeled using a non-linear inductor model in combination with a phenomenological parametric Maxwell type model of the damper.

Highlights

Magnetorheological (MR) fluids are well-known representatives of so-called smart materials
The electromagnetic circuits of MR valves are usually developed with soft magnetic alloys, the flux’s hysteresis should be accounted for in engineering an MR damper-based control system
As MR dampers are by principle solenoid actuators, the significance of hysteresis is important

Summary

Introduction

Magnetorheological (MR) fluids are well-known representatives of so-called smart materials. The material develops a yield stress when exposed to magnetic field (Rabinow, 1948), and it has been successfully used in commercial applications, i.e., semi-active vehicle dampers or powertrain mounts (Jolly et al, 1999). Supplying the electrical current to the coil results in inducing magnetic field in the flow channel, activating the fluid. Various factors make the conversion process complicated (Gołdasz et al, 2018a), namely, temperature, friction, material’s liability to sedimentation, non-linear magnetization characteristics of the materials of which the damper’s magnetic circuit is built, magnetic hysteresis, mechanical hysteresis, current driver dynamics, control coil dynamics, nonlinear relationship between the magnetic flux and the field-dependent yield stress, etc. The electromagnetic circuits of MR valves are usually developed with soft magnetic alloys, the flux’s hysteresis should be accounted for in engineering an MR damper-based control system. In MR dampers the hysteresis complicates controlling the output of these devices, and residual forces have a usually negative impact on the damper’s output at off-state forces in particular

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