Magnetorheological Shock Absorber Research Articles

Application of magnetorheological fluid in industrial shock absorbers

The paper presents investigation results of a semi-active industrial shock absorber with magnetorheological (MR) fluid, which is capable of controlling the stopping process of moving objects, e.g. on transportation lines. The proposed solution makes it possible to adjust the braking force (by electronic controller) to the kinetic energy of the moving object. The paper presents an overview of passive shock absorbers. Next, the design concept of a semi-active shock absorber with the MR fluid is proposed. The theoretical model and the simulation model of the MR absorber and the stopping process are presented. The paper reports investigations of a prototype MR shock absorber used to stop a mass moving on an inclined plane. The braking force of the absorber was changed by an electronic control system according to the current position of the moving mass. Finally, the simulation and investigation results are discussed and compared.

Design and control of electronic control suspension using a magneto-rheological shock absorber

This paper investigates the design and control of electronic control suspension (ECS) equipped with a controllable magneto-rheological (MR) shock absorber and appropriate control strategy. In order to achieve this goal, a cylindrical-type MR fluid shock absorber which satisfies the design specification for Macpherson strut-type suspension for a middle-sized commercial passenger vehicle is designed using an optimization methodology. After experimentally evaluating the field-dependent characteristics of the manufactured MR shock absorber, a quarter-vehicle MR ECS system, consisting of sprung mass, spring, tyre, controller, and the MR shock absorber, is established in order to investigate the ride comfort and driving stability performance. On the basis of the governing equation of motion of the suspension system, five control strategies (soft, hard, comfort, sport, and optimal mode) are formulated. The proposed control strategies are then experimentally realized with the quarter-vehicle MR ECS system. Control performances such as vertical acceleration of the car body and tyre deflection are evaluated in both time and frequency domains under various road conditions. In addition, a comparative study of vehicle motion with a full-vehicle MR ECS system is undertaken to investigate inherent control characteristics, using computer simulation.

Optimal design of MR shock absorber and application to vehicle suspension

This paper presents an optimal design of a magnetorheological (MR) shock absorber basedon finite element analysis. The MR shock absorber is constrained in a specific volume andthe optimization problem identifies geometric dimensions of the shock absorber thatminimize a multi-objective function. The objective function is proposed by considering thedamping force, dynamic range and the inductive time constant of the shock absorber. Afterdescribing the configuration of the MR shock absorber, a quasi-static modeling of the shockabsorber is performed based on the Bingham model of an MR fluid. The initial geometricdimensions of the shock absorber are then determined based on the assumption of constantmagnetic flux density throughout the magnetic circuit. The objective function of theoptimization problem is derived based on the solution of the initial shock absorber. Anoptimization procedure using a golden-section algorithm and a local quadratic fittingtechnique is constructed via a commercial finite element method parametric designlanguage. Using the developed optimization tool, optimal solutions of the MRshock absorber, which is constrained in a specific cylindrical volume defined byits radius and height, are determined. Subsequently, a quarter-car suspensionmodel with the optimized MR shock absorber is formulated and the vibrationcontrol performance of the suspension is evaluated under bump and sinusoidal roadconditions.

Modeling and Parameter Identification of a Shock Absorber Using Magnetorheological Fluid

This paper describes the modeling of a semi-active shock absorber that uses magnetorheological (MR) fluid, which is a material that responds to an applied magnetic field and changes its apparent viscosity. We propose a dynamic system in which the friction of a falling body is taken into consideration, and a model in which the shearing resisting force depends on the velocity of flow. The validity of this model and a Bingham model is verified by comparison of the experiment with a simulation. This study clarifies that resisting forces obtained by the simulation corresponded to those obtained by the experiment, and that the current model is effective in predicting the behavior of a MR shock absorber.

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This paper presents optimal design of controllable magnetorheological(MR) shock absorbers for passenger vehicle. In order to achieve this goal, two MR shock absorbers (one for front suspension; one for rear suspension) are designed using an optimization methodology based on design specifications for a commercial passenger vehicle. The optimization problem is to find optimal geometric dimensions of the magnetic circuits for the front and rear MR shock absorbers in order to improve the performance such as damping force as an objective function. The first order optimization method using commercial finite element method(FEM) software is adopted for the constrained optimization algorithm. After manufacturing the MR shock absorbers with optimally obtained design parameters, their field-dependent damping forces are experimentally evaluated and compared with those of conventional shock absorbers. In addition, vibration control performances of the full-vehicle installed with the proposed MR shock absorbers are evaluated under bump road condition and obstacle avoidance test.

Autonomous control system for a 3 DOF pitch-plane suspension model with MR shock absorbers

The study is concerned with an autonomous control system (ACS) for a 3 DOF pitch-plane suspension model comprising magnetorheological shock absorbers (MRAs). The model simulating a pitch-plane vehicle suspension with two independent spring–MRA sets in front and rear sections and a driver’s seat suspension with the third spring–MRA set is presented. The development of the ACS based on phyCORE-MPC555 single board computer and rapid prototyping of real-time controllers are described. Results of experiments in the open loop and feedback systems for the tested application are provided.

Dynamic Simulation and Test Verification of MR Shock Absorber under Impact Load

The magnetorheological (MR) shock absorber is one of the most promising new devices for vibration reduction. Many investigations have been carried out on low velocity and frequency applications of MR devices. The use of the MR shock absorber under impact load is of great interest. The now widely used MR damper models, such as the Bingham model, cannot explain sufficiently the shear thinning behavior under impact loads. However, the Herschel–Bulkley model can be used to explain the same. The main purpose of this study is to analyze the behavior of the MR shock absorber under impact load and to verify the analytical conclusions and experiments. First, some dynamic simulations on the MR shock absorber under impact loads in Matlab and Simulink are carried out. The model describes the dynamic characteristics especially the shear thinning behavior of the shock absorber, based on this model, then analyzes the variations of piston acceleration and back cavity pressure of MR shock absorber at both same and different flow indices. A test rig is developed to test the characteristics of the long-stroke MR shock absorber under impact loads. Comparisons between the simulation and the test results are made to validate our conclusions. The results indicate that the peak acceleration value of the piston rod and the pressure of the back cavity are decided by the peak value and the duration of the impact force. The peak value of the acceleration and the cavity pressure cannot be changed, but the transitional time of the acceleration of the piston and the pressure of the back cavity of MR shock absorber can be controlled by changing the applied current in the electromagnetic coil. MR shock absorbers will be the most promising shock reduction device under an impact environment.

Study on design methodology of magneto-rheological fluid Shock absorbers employing Eyring constitutive model

In this paper, the Eyring constitutive model parameters have been identified via minimization of the error function defined as error sum between shear stresses from experimental tests in laboratory of Chongqing University and shear stresses depicted the Eyring constitutive model. Authors have theoretically set up flow control equations for magneto-rheological (MR) fluids in annular channels using the Eyring constitutive model and N-S equations in hydrodynamics. The velocity profiles of MR fluids through annular channel are obtained by means of flow control equations mentioned above. In accordance with piston velocity and annular channel geometrical parameters of MR fluid shock absorber, MR shock absorber performances have been predicated by means of analytical methodology developed in this paper. In the light of technical requirements of front suspension of Chanan star minibus, a MR fluid shock absorber, which is designed and fabricated in Chongqing University according to design method presented in this paper, has tested by electro-hydraulic servo vibrator and its control system in National Center for Test and Supervision of Coach Quality. The experimental results reveal that the analytical methodology and design theory are reasonable.

Controllability of MR shock absorber for vehicles

In the paper, shock absorbers with magnetorheological (MR) fluids were described. These elements can be used in many applications related to vehicle machines such as bumpers, dampers, shock absorbers, vibration eliminators, etc. Basic theoretical relationships which allow design and modelling of MR fluid shock absorbers are shown. Experimental designs of MR absorber and some example results of research were presented and discussed. The application of PI force controller used to improve the dissipation characteristic of built MR shock absorber has been shown.

Double adjustable shock absorbers utilising electrorheological and magnetorheological fluids

Double adjustable shock absorbers allow for independent adjustment of the yield force and post-yield damping in the force versus velocity response. To emulate the performance of a conventional double adjustable shock absorber, an electrorheological (ER) and magnetorheological (MR) automotive shock absorber were designed and fabricated at the University of Maryland. For the ER shock absorber, an applied electric field between two tubular electrodes, located in the piston head, increases the force required for a given piston rod velocity. For the MR shock absorber, an applied magnetic field between the core and flux return increases the force required for a given piston rod velocity. For each shock absorber, two different shaped gaps meet the controllable performance requirements of a double adjustable shock absorber. A uniform gap allows for control of the yield force of the shock absorber, while a nonuniform gap allows for control of the post-yield damping. Force measurements from sinusoidal displacement cycles, recorded on a mechanical damper dynamometer, validate the performance of uniform and non-uniform gaps for adjustment of the yield force and post-yield damping, respectively.