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Owing to the complex nonlinear hysteresis of magnetorheological (MR) damper, the modeling of an MR damper is an issue. This paper examines a novel MR damper hysteresis model based on the grey theory, which can fully mine the internal laws for the data with small samples and poor information. To validate the model, the experiment is conducted in the MTS platform, and then the experimental results are compiled to identify the model parameters. Considering the complexity of the grey model and its inverse model solution, the grey model is simplified in two ways based on the grey relational analysis method. Furthermore, the simplified grey model compares to other models to prove the superiority of the grey model. The analysis suggests the fitting results correspond to the measured results, and the mean relative error (MRE) of grey model is within 2.04%. After the grey model is simplified, its accuracy is slightly reduced, while its inverse model is easier to solve and makes a unique solution. Finally, compared with the polynomial and Bouc-Wen model, the novel model with fewer identification parameters has high accuracy and predictive ability. This novel model has fabulous potential in designing the control strategy of MR damper.

A systematic modeling study is conducted to predict the dynamic response of magnetorheological (MR) damper based on a refined constitutive model for MR fluids. A particle-level simulation method is first employed to probe the microstructured behavior and rheological properties of MR fluids, based on which the refined constitutive model is developed. The constitutive model is further validated by comparing the predicted results with the data obtained from microscopic simulations and existing experiments. It is revealed that the proposed constitutive model has comparable accuracy and good applicability in representing MR fluids. Subsequently, a computational fluid dynamics (CFD) model is established to explore MR damper’s behavior by using the proposed constitutive model to describe the fluid rheology. For better capturing the dynamic hysteretic behavior of MR damper, a modified parametric model is developed by combing the Bingham plastic model and the proposed constitutive model. The modified model for MR damper shows its validity and superiority over the existing Bingham plastic models.

Mostly, magnetorheological (MR) dampers were optimized based on individual performance, without considering the influence of structure parameters change on vehicle performance. Therefore, a multi-objective optimization scheme of MR damper based on vehicle dynamics model was proposed. The finite element method was used to analyze magnetic flux density distribution in tapered damping channel under different structure parameters. Furthermore, the damping force expression of the tapered flow mode MR damper was derived, and the damping force was introduced into the vehicle dynamics model. In order to improve the ride comfort and operation stability of the vehicle, a collaborative optimization platform combining magnetic circuit finite element analysis and vehicle dynamics model was established. Based on this platform, the optimal design variables were determined by comfort and stability sensitivity analysis. The time domain optimization objective and frequency domain optimization objective are proposed simultaneously to overcome the lack of time domain optimization objective. The results show that compared with the time domain optimization and the initial design, the suspension dynamic deflection, tire dynamic load and vehicle body vertical acceleration are decreased after the time-frequency optimization. At the same time, in the frequency domain, the amplitude of vibration acceleration in each working condition is significantly reduced.

As one of the most important components in the semi-active damping system, the performance of MR damper directly determines the damping capacity of the damping system. In order to make the damping system has excellent damping effect, it is necessary to optimize the working performance of the MR damper. Therefore, Non-Dominated Sorting Genetic Algorithm version II (NSGA-II) was applied to optimize the structure of MR dampers in this paper. Firstly, the structural scheme of MR damper was proposed. Secondly, the design principle of MR damper was described, and the magnetic circuit material and MR fluid were selected. Thirdly, taking the maximum dynamic range and the minimum number of turns of electromagnetic coil as the optimization objective, the structure of MR damper was optimized by NSGA-II. The structural parameters of MR damper were determined in the Pareto optimal solution set based on the principle of minimum mass. Finally, through the magnetic simulation and the performance testing of the MR damper, it was verified that the MR damper has reasonable magnetic circuit and excellent performance. And the design results meet the requirements. The proposed optimization method can provide a theoretical basis for the optimal design of related damping devices.

This work presents landing efficiency control of a six-degree-of-freedom aircraft model, which has a controllable landing gear system with magnetorheological damper. Due to lengthy contents, this work is divided into two parts. In Part 1, both the kinematic and dynamic equations of the six-degree-of-freedom aircraft model are derived. After determining the principal design parameters of magnetorheological damper based on commercial Beechcraft Baron B55 (passive oleo-strut type) damper, the kinematic equations are derived using the aircraft body coordinate frame and homogeneous coordinates of the reference frame, while the dynamic equations are derived using Euler–Lagrange equation to represent the heave, roll, and pitch motions of the aircraft model. In Part 2, the landing performance based on landing efficiencies is analyzed through the landing motions using various controllers.

Magnetorheological damper is a typical semi-active control device. Its output damping force varies with the internal magnetic field, which is a key factor affecting the dynamic performance of the magnetorheological dampers. Existing studies about the magnetic field of magnetorheological dampers are limited to theoretical analysis; thus, this study aims to experimentally explore the complicated magnetic field distribution inside the magnetorheological dampers with multiple coils. First, the magnetic circuit of a three-coil magnetorheological damper was theoretically analyzed and designed, and the finite element model of the three-coil magnetorheological damper was set up to calculate the magnetic induction intensities of the damping gaps in different currents and numbers of coil turns. A three-coil magnetorheological damper embedded with a Hall sensor was then manufactured based on the theoretical and finite element analysis, and internal magnetic field tests under different conditions were carried out to obtain the actual magnetic induction intensities. At last, the magnetic field coupling model of the three-coil magnetorheological damper was proposed by introducing a coupling coefficient to describe the complex magnetic field distribution due to the strong coupling effect of the three coils, and the results calculated by the proposed model agreed well with the finite element analysis and magnetic field test data. The proposed model lays a foundation for the optimal design of the magnetic circuit and the mathematical model of multi-coil magnetorheological dampers.

Semi-active systems using magnetorheological fluids have been realized in many novel devices such as linear dampers, rotary dampers, brakes, and so on. Rotary vane-type magnetorheological damper is one such device that uses magnetorheological fluid as a hydraulic medium and a controllable magnetorheological valve to generate variable resistance. This device, due to its limited angle motion, lends itself to a natural application for prosthetic knee joint. In this article, a bypass rotary vane-type magnetorheological damper suitable for prosthetic knee device is designed. In the proposed design, the rotary vane chamber and the bypass magnetorheological valve are connected using hydraulic cables and ports. The design of rotary cylinder is implemented based on the largest possible dimensions within the envelope of a healthy human knee, while the magnetorheological valve is designed optimally using a multi-objective genetic algorithm optimization. Off-state braking torque, induced on-state braking torque and mass of the valve are selected as three objectives. The torque and angular velocity requirements of the normal human knee are used as design limits. The optimal solution is chosen from the obtained Pareto fronts by prioritizing the objective of weight reduction of magnetorheological valve. The optimal solution is capable of producing a damping torque of 73 Nm at a design speed of 8.4 rpm and current supply of 1.9 A. Potential benefits offered by this design when compared with multi-plate magnetorheological brake are flow mode operation, large clearance gap, and fewer design components, thus reducing the manufacturing complexity.

Conventional skyhook-based ON–OFF control switches the damping force on a vibration suppression target according to the sign of the product of the target and relative velocities (which is called the condition function). Here, we propose a control strategy that uses a novel condition function for improved performance. The proposed strategy is formulated based on the theory of forced vibration with base excitation. Its effect upon semi-active vibration performance is investigated via numerical simulations and experimental tests of the vibration suppression of a small structure equipped with a magnetorheological (MR) damper. In the simulations, the proposed control strategy can offer high-performance semi-active vibration suppression, even in the presence of force delays in the damper. The experiments show that the displacement response with the proposed control is lower than that with the conventional skyhook-based control over the entire frequency range; furthermore, the desired performance can be achieved when the proposed condition function is used with velocity-proportional control. The simplicity and high performance demonstrated by the proposed control strategy make it applicable to semi-active vibration suppression of practical systems, even in the presence of unavoidable force delays in controllable dampers.

Mini-magnetorheological damper is modeled using dissipative particle dynamics method, as a molecular modeling technique by applying various arrangement patterns of rough sections on the surface area of piston as four proposed scenarios of A, B, C, and D to obtain optimal damper performance. Modeling is developed to achieve 10-N damping force utilized in micro-machines and compared to experimental results that show good conformity. Weierstrass–Mandelbrot function is used to apply rough surface profile on the piston, and bounce back boundary condition is utilized as no-slip boundary condition. Results of modeling show that 140-CG magnetorheological fluid is suitable as the agent fluid. Also, it is observed that by increasing fractal dimension of roughness profile, damping force has an initial enhancement and then trends to a constant value. Results shown by utilizing Bouc–Wen model and genetic algorithm method and fractal dimension of roughness profile of 1.5 using at the beginning and the end of the piston as presented in scenario B; by applying 20% magnetic field strength, considered damping force of 10 N is achieved within 2 s, while under conventional conditions, using the smooth surface area of piston, more damping time is needed and more electrical energy is used than the developed model.

In this work, a new method of using a magnetorheological damper to improve the self-adaptive ability of a rotor system to rub-impact is developed. To validate the feasibility of this method, a finite element model of the rub-impact rotor system with magnetorheological damper is investigated. A revised formula describing the relationship between the yielding shear stress and magnetic field intensity is proposed. Focusing on the mitigation effect of magnetorheological damper on the nonlinear dynamic response of the rotor system, numerical simulation is conducted. The results show that magnetorheological damper has a considerable effect on the vibration and stability of a rub-impact rotor system. When a suitable current is applied, magnetorheological damper can effectively mitigate the vibration of the rotor system to prevent rub-impact. If contact of the rotor/stator is inevitable, magnetorheological damper can further stabilize heavy rub-impact to slight rub-impact by adjusting the current to an appropriate value. This research reveals the influence mechanisms of magnetorheological damper on normal and rub-impact rotor systems and is helpful for vibration control and fault self-healing of rotating machinery.

This article reports a compact stiffness controllable magnetorheological damper with a self-powered capacity. First, the structure, working mechanism, and analysis of the damper are presented. After the prototype of the magnetorheological damper, experimental tests were conducted to evaluate its variable stiffness feature and self-powered generation capability using a hydraulic Instron test system. The testing results demonstrate that its stiffness variation range can reach 70.4% when the applied current increases from 0 to 2 A. The energy generating capability of the magnetorheological damper was also evaluated using the Instron testing system under a harmonic excitation with 0.15 Hz frequency and 30 mm displacement. The testing results illustrate that the self-powered generation component can generate 2.595 W effective power, which is enough to control the magnetorheological component of the damper. The successful development, theoretical analysis, and experimental testing of this new variable stiffness self-powered magnetorheological damper make the concept of energy-free variable stiffness magnetorheological damper feasible.

In this research, a new type of magnetorheological damper for a small-sized aircraft landing gear system is proposed and its performance is evaluated with respect to design parameters of the magnetic core. As a first step, a new configuration of magnetorheological damper for the landing gear system, which consists of orifices, recoil valve, and magnetic circuits, is introduced with working principles. After formulating the governing equations of motion, six different models of magnetorheological damper featuring different number of magnetic core and different pole length are chosen to investigate both the landing stability and the efficiency. Subsequently, the distribution of the magnetic field intensity of each model is analyzed through the finite element method, followed by the calculation of the field-dependent damping force to be used for the landing simulation, which is undertaken by adopting the dynamic model of a half airplane landing gear system. In order to identify the significance of the magnetic core parameters, the landing stability is judged from the sign of the minimum force and the landing efficiency is determined from the energy dissipation during the vertical drop motion.

In the present work, a new unsteady analytical model is developed for magnetorheological fluid flow through the annular gap which is opened on the piston head of twin tube magnetorheological damper, considering fluid inertia term into the momentum equation. This new unsteady model is based on Stokes’ second problem that is extended for magnetorheological fluid flow between finite oscillating parallel plates under the pressure gradient. A quasi-static analysis is also developed for magnetorheological fluid flow in twin tube damper, to compare its results with present unsteady solution and to show the effect of magnetorheological fluid inertia. The obtained results are validated experimentally and then, a parametric study is presented using both unsteady and quasi-static analysis. The effect of fluid inertia term is investigated on force–displacement and force–velocity loops, magnetorheological fluid velocity profile, pressure drop, phase difference between pressure drop and flow rate and change of plug thickness with time duration. According to the obtained results, quasi-static analysis included considerable error respect to new unsteady analysis as the gap height, magnetorheological fluid density, excitation frequencies and amplitudes are increased and yield stress is decreased. It is found that the plug thickness is considerably affected by inertia term of magnetorheological fluid.

This study focuses on experimental investigation of a fail-safe, bi-linear, liquid spring magnetorheological damper system for a three-dimensional earthquake isolation system. The device combines the controllable magnetorheological damping, fail-safe viscous damping, and liquid spring features in a single unit serving as the vertical component of a building isolation system. The bi-linear liquid spring feature provides two different stiffnesses in compression and rebound modes. The higher stiffness in the rebound mode prevents a possible overturning of the structure during rocking mode. For practical application, the device is to be stacked together along with the traditional elastomeric bearings that are currently used to absorb the horizontal ground excitations. An experimental setup is designed to reflect the real-life loading conditions. The 1/4th-scale device is exposed to combined dynamic axial loading (reflecting vertical seismic excitation) and constant shear force that are up to 245 and 28 kN, respectively. The results demonstrate that the device performs successfully under the combined axial and shear loadings and compare well with the theoretical calculations.

In this article, a robust state-feedback H∞ control for semi-active scissors linkage seat suspension with magnetorheological damper is investigated to reduce low-frequency and high-amplitude vibration, leading to health disorders in drivers or passengers. First, the stiffness and damping characteristics of the semi-active scissors linkage seat suspension are analyzed and a simplified model of the semi-active scissors linkage seat suspension is introduced. Then, the forward and inverse models of magnetorheological damper are described by the neural network method. Furthermore, the robust state-feedback H∞ control is established by considering the system uncertainties. The proposed approach is finally validated by experiment on a test rig under different sinusoidal excitations and load masses. Experimental results show that the human vibration is reduced up to 47.66% compared with the uncontrolled system.

This article presents an optimal control strategy with fuzzy compensation for a magnetorheological fluid damper in control of a full-scale gun recoil buffering system. The novel control strategy combines the optimal control, in which no measurement feedback needed and the fuzzy logic control which is independent of any theoretical model. The theoretical optimal controllable damping force rule, as a fail-safe control output when the measurement system fails under the extreme condition of impact loading, is derived from the analytical solution of the kinematic equation of the recoil system with a magnetorheological damper. A one-dimensional fuzzy controller and a two-dimensional fuzzy controller are both designed and performed by simulation in order to evaluate the effectiveness of fuzzy control strategy as compensation in the magnetorheological recoil system. A magnetorheological damper for the real firing impact loading is designed and manufactured. Furthermore, an experimental study is carried out to evaluate the optimal control strategy with fuzzy compensation for magnetorheological damper on a firing test rig. The experimental results indicate that the proposed control strategy in this article obtains better buffering performance comprehensively compared with the conventional control strategies.

Magnetorheological damper is one of the most promising smart devices for vibration mitigation of structures subjected to dynamic loads. In order to fulfill the value of magnetorheological damping control, a feasible mechanical model of magnetorheological dampers with simplicity and sufficient accuracy is usually required in practice. It comes up, however, with a challenging issue for the modeling of large-size magnetorheological dampers due to physical constraints on the performance test. The large-size magnetorheological damper is typically modeled in up-scaling parameters associated with models of the small-size magnetorheological damper. This treatment remains open since a size effect hinges upon the intrinsic non-linearity inherent in the device. In this article, a dynamic test of a small-size magnetorheological damper is performed first. The relevance of damper force with the input current and excitation frequency is well revealed. The modified Bouc–Wen model is employed to logically represent the dynamic behaviors of magnetorheological dampers. Identification of model parameters in typical loading cases is then proceeded, of which the functional relationship against input current is established. The size effect of magnetorheological dampers is further addressed through investigating the functional relationship relevant to maximum outputs of 200, 10, and 5 kN. It is indicated that the small-size magnetorheological damper needs more number of control parameters than the large-size magnetorheological damper. Moreover, a linear current relevance of model parameters appears in the small-size magnetorheological damper, while a quadratic current relevance of model parameters appears in the large-size magnetorheological damper. Size effect of magnetorheological dampers arises to be well-marked in the range of low current and becomes unapparent in the range of high current. Besides, the validation of modified Bouc–Wen model is carried out that reveals the applicability of the model with case-optimized parameters.

This article presents the development of a novel magnetorheological damper with velocity self-sensing capability. The velocity self-sensing mechanism, based on the optical tracking technology and numerical circuit technology, was adopted. The configuration and work principle of the velocity self-sensing magnetorheological damper were presented. The self-sensing circuits, built with optical mouse sensor and microcontrollers, were integrated into the hollow upper lid. The hollow upper lid provides a suitable place for the self-sensing circuits, can be installed and disassembled easily, and can be maintained efficiently. The velocity self-sensing magnetorheological damper prototype with 10 kN capacity was theoretically analyzed, fabricated, and investigated. Finally, the damping performance, self-sensing performance, and self-sensing control capability were tested and analyzed. The results indicated that self-sensing velocity unit has high accurate monitoring capability over a wide range of working conditions. The velocity self-sensing magnetorheological damper–based control system has sufficient ability to control the magnetorheological damper.

This study investigates a newly developed positioning system based on a rotary magnetorheological damper with power generation capability, comprising an electromagnetic power generator (energy extractor) generating electrical power, an magnetorheological damper which alters the damping characteristics of the system and an electrical interface, connected in between the coil of the generator and the damper control coil, which conditions the voltage output from the generator. Structural configurations of the damper and the generator are outlined, and the results of their testing and the testing done on the entire system are summarised, covering the tests conducted with and without the interface, under the idle run and under load in the assumed velocity range. The objective of the work is to examine the performance of the proposed positioning system through experiments. Results of the system testing in the uncontrolled case (passive system) and in the controlled one (semi-active system) in a purpose-built test rig are compared and discussed. Three design options of the electrical system controlling the damper are explored. In the first option, the damper is assumed to be controlled starting from the initial moment of the motor shaft’s motion, and in the second option, the control action begins at the instant when the motor shaft assumes the present position. The third variant is similar to the first one except that an additional condenser is connected behind the Graetz bridge. The results confirm the adequacy of the developed positioning system and demonstrate an improvement in control of the system’s dynamic behaviour.

The current semi-active or even active control strategies have been developed to address a few drawbacks, such as unwanted large displacements created at the base level and system deficiency in adaptation to different types of seismic excitations, in the base isolation systems. In this article, two control strategies, multi-objective modified clipped optimal and adaptive fractional order fuzzy proportional–integral–derivative, are proposed for semi-active control of a smart base-isolated structure equipped with a magnetorheological damper. The main objective is to reduce the displacement of isolation system without allowing significant increase in the acceleration of superstructure for both far-field and near-field earthquake excitations. Using proper fitness functions, the weighting matrices of the multi-objective modified clipped optimal controller are tuned using multi-objective optimization. Then, the parameters of the fractional order fuzzy proportional–integral–derivative controller are obtained. Next, the fuzzy rule weights of the fractional order fuzzy proportional–integral–derivative controller are updated online based on the values of ground motion and structural responses using an adaptive strategy. For comparison, two control cases in which the magnetorheological damper is in passive mode, passive-off and passive-on, are considered. Numerical simulations show that the proposed adaptive fractional order fuzzy proportional–integral–derivative controller better mitigates the seismic responses of a base-isolated structure excited by a range of real-data earthquakes.

This article attempts to clarify the question of what the essential difference between the optimal and “clipped-optimal” control is that the Hamilton–Jacobi–Bellman or Hamilton–Jacobi–Isaacs partial differential equation is linear or nonlinear. An adaptive optimal control based on policy iteration to the constrained semi-active vehicle suspension system with a magnetorheological damper is presented. The problem of improving the optimal performance of semi-active control suspension system is converted to L2-gain optimal control problem. A two-player policy iteration scheme is employed to solve the Hamilton–Jacobi–Isaacs equation by use of neural networks to approximate optimal policies and value functions in the admissible global region. Simulation results demonstrate that the adaptive optimal controlled semi-active vehicle suspension system outperforms greater than that of the clipped-LQR controlled.

Magnetorheological damper has been widely used for improving vehicle ride comfort and handling because of its excellent performance. Numerous reinforced structures of magnetorheological dampers have been developed to enhance their dynamic performance and heat dissipation. This article presents a novel pumping magnetorheological damper with one-way pumping flow and dual-stage coil-in-cylinder magnetic system. Its dynamic model and inductive time constant are derived. Then, the structural parameters are optimized via a fast multi-objective genetic algorithm. Furthermore, a pumping magnetorheological damper prototype is tested and evaluated. The proposed pumping magnetorheological damper is able to perfectly balance the dynamic performance, heat dissipation efficiency, and structure flexibility via one-way pumping flow and coil-in-cylinder magnetic system, which has a promising application prospect in semi-active suspensions.

An evolving encoding scheme is presented in this article for a fuzzy-based nonlinear system identification scheme, using the subtractive fuzzy C-mean clustering and a modified version of non-dominated sorting genetic algorithm. This method is able to automatically select the best inputs as well as the structure of the fuzzy model such as rules and membership functions. Moreover, three objective functions are considered to satisfy both accuracy and compactness of the model. The developed method is then employed to identify both forward and inverse models of a highly nonlinear structural control device, that is, magnetorheological damper. Experimental results showed that the proposed evolving Takagi–Sugeno–Kang fuzzy model can identify and grasp the nonlinear behaviour of magnetorheological damper very well with minimal number of inputs and fuzzy rules.

For efficient fast control of suspension systems with magnetorheological dampers controlled by semi-active algorithms, the time response of the magnetorheological damper is one of the most important parameters which influences the performance of the suspension system. The time response of commercial magnetorheological dampers with common controllers is in the range of tens of milliseconds, which is too long for efficient real-time control of car suspension. This article describes the ways how to design magnetorheological damper with short response time. First part describes the elimination of long time response caused by high inductance of electrical circuit of magnetorheological damper using current controller. The second part describes elimination of long time response caused by eddy currents which are induced in the magnetic circuit of magnetorheological damper. The new piston of the magnetorheological damper is designed from material with high relative permeability but low electrical conductivity (ferrite). The time responses of magnetic induction and damper forces were measured and compared to original commercial Delphi damper. Results showed rapid improvement in time response when the current controller is used and when the piston is constructed from ferrite materials.

Excessive torsional vibrations in mechanical systems with rotating mechanical components result in noise, excessive stresses, or even fatigue failure if not suppressed or controlled properly. Accordingly, they should be suppressed or controlled immediately to ensure system’s reliability. In this study, a hybrid torsional vibration damper is proposed incorporating a conventional centrifugal pendulum vibration absorber and a magnetorheological damper. While centrifugal pendulum vibration absorbers are simple and reliable than passive torsional vibration absorbers, their performance is limited to the designed tuning conditions. Magnetorheological dampers have recently received considerable attention due to their inherent fail-safe feature, low power requirement, and capability to attenuate vibration under unpredictable environmental conditions. This research aims at developing a novel hybrid torsional vibration damper combining conventional centrifugal pendulum vibration absorber with the magnetorheological rotary damper in which the centrifugal pendulum vibration absorber has been connected to the cylindrical housing of the magnetorheological damper. The analytical model of the rotor system integrated with proposed hybrid torsional damper has been developed. The superior performance of the proposed torsional damper has been then demonstrated by comparing the results with those of rotor system without any damper, rotor system with only centrifugal pendulum vibration absorber, and finally rotor system with only magnetorheological rotary damper.

© SAGE Publications. Laminated magnetorheological elastomer base isolator is regarded as one of the most promising candidates for realizing adaptive base isolation for civil structures. However, the intrinsic hysteretic and nonlinear behavior of magnetorheological elastomer base isolators imposes challenge for adopting the device to accomplish high-accuracy performance in structural control. Therefore, it is essential to develop an accurate model for symbolizing this unique characteristic before designing a feedback controller. So far, some classical parametric models, such as Bouc-Wen, Dahl, and LuGre, have been proposed to depict the hysteretic response of magnetorheological devices, that is, magnetorheological damper, which may also be used for describing the nonlinear behavior of magnetorheological elastomer base isolator. However, the parameter identification is difficult to implement due to the nonlinear differential equations existing in these models. Considering this problem, this article proposes a nonparametric model, that is, an artificial neural network-based model with 3 input neurons, 18 hidden neurons, and 1 output neuron, to predict the magnetorheological elastomer isolator behavior. In this model, the ant colony algorithm is employed for model training to obtain the optimal weights based on the force-displacement/velocity data sampled from the magnetorheological elastomer isolator. Finally, experimental data are used to validate the effectiveness of the proposed artificial neural network-based model with the good forecasting results.

This article presents the development of a novel magnetorheological damper which has a self-sensing ability. In this study, a linear variable differential sensor, which was based on the electromagnetic induction mechanism, was integrated with a conventional magnetorheological damper. The working principle, configuration, and prototype of the displacement differential self-induced magnetorheological damper based on the integrated linear variable differential sensor technology were presented. A mathematical model of the proposed displacement differential self-induced magnetorheological damper was established. The finite element model was built with two-dimensional Maxwell software and the magnetic simulations were presented. With this approach, the influence of the flux leakage, the winding cylinder in different basic values of structure parameters, and materials were determined to obtain an optimal displacement differential self-induced magnetorheological damper. Finally, the dynamic performance of the displacement differential self-induced magnetorheological damper was evaluated with a fatigue test machine. The experimental results indicated that the developed displacement differential self-induced magnetorheological damper based on the integrated linear variable differential sensor technology can output controllable damping force and displacement relative self-induced voltages simultaneously.

A new design optimization methodology for the optimal design of a single-coil annular magnetorheological valve constrained in a specific volume inside a magnetorheological damper has been presented in this article. The methodology combines the finite element model, with the design of experiments and response surface techniques in order to develop approximate response surface functions for the magnetic field intensity across the activation length of a magnetorheological valve orifice with respect to identified design variables. The accuracy of the developed response surface functions over the entire design space has been verified. The developed analytical response functions have then been used in Bingham plastic model, which is based on the steady behavior of a magnetorheological fluid in order to derive the field-dependent performance functions of the magnetorheological damper, which can be effectively used in the design optimization problems. The design optimization problem has been formulated for single- and multiobjective performance functions using sequential quadratic programming technique and the genetic algorithm to find the global optimum geometrical parameters of the magnetorheological valve. Finally, a proportional–integral–derivative controller has been designed to evaluate the closed-loop performance of the optimally designed magnetorheological valve confined in a magnetorheological damper used in a quarter-car suspension model.

The magnetorheological dampers have been extensively studied given their benefits such as fail-safe manner, low power requirements, relative fast response, and large force capacity and robustness. To take advantage of this remarkable device, a good model is required to accurately and effectively predict the real-time damping force in magnetorheological damper in order to apply the appropriate control actions to improve the response of the structural system. In this article, a new practical model is proposed to better characterize the hysteresis phenomenon in magnetorheological dampers. The model considers the displacement, velocity, and acceleration excitations as well as the current excitation as input variables and includes a reduced number of constant parameters to be determined. Since the displacement, velocity, and acceleration variables can be obtained in real time from adequate sensors, it is easy and practical to predict the current excitation required to generate the specific hysteresis force. The hysteresis damping forces predicted by the proposed model are validated with those experimentally obtained for different current, amplitude, and frequency of excitation, and a very good correlation has been observed.

This study aims to get a deep insight of the inherent hysteresis behavior of magnetorheological fluid dampers and to develop the method of designing such hysteresis. Taking into account the compressibility of magnetorheological fluid, a physical model of magnetorheological dampers is developed by establishing the flow rate equations for two chambers. The model is validated by a set of the experimental data from a literature. As a special case of the proposed physical model, a lumped parameter physical model which can explain the hysteresis in a more straightforward way is derived and validated too. The fact that the viscous force can be ignored compared to the Coulomb force reduces the lumped parameter physical model to its simplest form, that is, a friction element representing the Coulomb force is connected in series with a spring element representing the compressibility of fluid. It is this simple two-element physical model that captures the essence of the hysteresis behavior, on the basis of which, the mechanism of the hysteresis generation is explored in great detail, and the formula is also derived for calculating the hysteresis width. Finally, the design method of the hysteresis behavior is illustrated by a specific example.

In this article, ongoing studies to apply semi-active control devices to reduce undesired vibrations of civil engineering structures are investigated. In doing so, the barrier of the nonlinear inner mass single unit impact dampers is equipped by the magnetorheological fluid dampers. For convenience, this kind of impact dampers is briefly named smart impact dampers. Dynamic behavior of a vibratory system equipped with the smart impact damper is modeled based on the modified Bouc–Wen model for the magnetorheological damper. Performance of the smart impact damper to suppress free vibration of an Euler–Bernoulli beam is investigated. Furthermore, effects of varying applied current to the magnetorheological fluid damper on vibratory behavior of the beam are illustrated in user-oriented charts. The analysis results show that the smart impact dampers with optimal parameters can suppress undesired vibrations much better than conventional impact damper systems.

In robotics and haptics, actuators that are capable of high force output with compact size are desired for stable and stiff interfaces. Magnetorheological brakes are viable options for such impleme...

Magnetorheological fluid composites were formulated in this study to investigate their performance for potential use in landing gear hydraulic systems, such as shock struts. The magnetorheological fluids synthesized here utilized three hydraulic oils certified for use in landing gear, two average diameters of spherical magnetic particles, and a lecithin surfactant. The magnetorheology of these fluids was characterized, including (a) magnetorheology (yield stress and viscosity) as a function of magnetic field, (b) sedimentation analysis using an inductance-based sensor, (c) cycling of a small-scale magnetorheological damper undergoing sinusoidal excitations at frequencies of 2.5 and 5 Hz, and (d) impact testing of an magnetorheological damper for a range of magnetic field strengths and velocities using a free-flight drop tower facility. The goal of this research is to analyze the performance of these magnetorheological fluid composites, compare their behavior to standard commercial magnetorheological fluid, and determine their feasibility for use in helicopter landing gear.

It is known that a quasi-static analysis without considering fluid inertia is usually used for magnetorheological damper design. However, fluid inertia terms need to be incorporated into the governing Navier–Stokes equation in practical application for oscillatory or unsteady fluid flow. In this article, an unsteady flow of magnetorheological fluids within flow mode magnetorheological dampers was theoretically investigated under sinusoidal displacement excitation. Based on the governing Navier–Stokes equation, incorporating the boundary and initial conditions, central numerical velocity solutions of magnetorheological fluids within magnetorheological damping channel were developed and used to confirm the damping force using both Bingham plastic and Herschel–Bulkley models of magnetorheological fluids. To simplify the governing equation of Herschel–Bulkley flow, an approximation method replacing Herschel–Bulkley model velocity with Bingham plastic model velocity during calculating effective viscosity shear rate of Herschel–Bulkley model is proposed and used. For given magnetorheological fluid properties and flow mode magnetorheological damper geometry, under different yield stresses, sinusoidal excitation frequencies, and power-law exponent of Herschel–Bulkley model, the effects of magnetorheological fluid inertia terms on work and characteristic diagrams of magnetorheological dampers are discussed.

This article presents a transient model of a magnetorheological damper, which takes into account the effect of Duhamel’s superposition of the variation of magnetorheological damper piston velocity with time. The magnetorheological fluid flow channel studied in this work is in the shape of an annular gap between the piston and the bore of the cylinder of the magnetorheological damper. The model was derived using a Bingham plastic model for shear stress versus shear rate behaviour of the magnetorheological fluid by applying the combination of Laplace and Weber transforms to the Navier–Stokes equations for obtaining the analytical solutions of the velocity in the sheared regions in a given cross section of an annular magnetorheological fluid flow channel. The solution is further modified to include the effect of time variation of piston velocity by using Duhamel’s superposition integral. The equations of the velocity profiles have been used to obtain the equations of mass flow rate balance, velocity compatib...

As a semiactive control device, magnetorheological dampers have been paid more attention due to their high controllability, fast response, and low power demand. One of the important characteristics for magnetorheological dampers is magnetic saturation, that is, the maximum damping force will reach some value and no longer vary with the increasing input current, especially in the presence of large magnetic flux density. In order to take this problem into account fully, tests on a shear-valve mode magnetorheological damper are carried out to consider the effects of input current, displacement amplitude, and loading frequency on the properties of the magnetorheological damper during magnetic saturation situation first. Then, the magnetic saturation phenomenon of the magnetorheological damper is simulated using the finite element method, and the numerical simulation results are compared with the experimental results. Finally, a magnetic saturation mathematical model is proposed to describe the properties of the magnetorheological damper, and the numerical hysteresis curves of the proposed magnetic saturation mathematical model, the Bingham model, and the Bouc–Wen model are compared with the experimental results. It can be concluded that the magnetic saturation mathematical model can describe the influence of input current, displacement amplitude, and excitation frequency on the properties and the magnetic saturation property of the magnetorheological damper.

A magnetorheological damper is evaluated under exhaustive experimental scenarios, generating a complete database. The obtained database includes classical tests and new proposals emphasizing the frequency contents. It also includes the impact of the electric current fluctuations. The variety of the performed experiments allows us to study the magnetorheological damper force dynamics. A brief description of the damper behavior and a categorization of experiments based on driving conditions and target applications on vehicle dynamics are discussed. The identification of two magnetorheological damper models and their cross validation emphasize the importance of the persistence of experimental inputs and the combinations of rod displacement and electric current sequences for better modeling. New findings in design of experiments for model identification are presented.

In this article, an MRD50 type of large-scale magnetorheological shock absorber was designed and manufactured in Smart Materials and Structures Laboratory of Nanjing University of Science and Technology. Upon providing a brief background on magnetorheological dampers, the detailed structure of this developed large-scale magnetorheological shock absorber was depicted. A suit of hardware-in-the-loop simulation platform under high impact load excitation was introduced for a weapon system. A series of tests were conducted to establish the dynamic behaviors of magnetorheological shock absorber under impact loads. The test results show that the inertia damping force should not be ignored like a common magnetorheological damper because of the large acceleration from the impact load. Based on the theory model and the experimental data, index parameters of magnetorheological fluid and other structural parameters in Herschel-Bulkley-Inertia model were identified by using the least square algorithm. In order to evaluate the controllability of large-scale magnetorheological shock absorber applied into high impact loads, three control algorithms, including on-off control, proportional-integral-derivative control, and fuzzy control algorithm, were used in tests to control the dynamic behavior of magnetorheological shock absorber, and some results of the controllability tests were exhibited in this article. In conclusion, the results indicated that the developed large-scale magnetorheological shock absorber was indeed able to effectively control the recoil dynamics. © The Author(s) 2012.

A quantizing method, single parameter adjustment method (SPAM), is proposed so that the selection of controlled damping parameters of the magnetorheological (MR) damper models can be well founded. By using SPAM, only one parameter is identified each time, and the controlled damping parameters are selected according to their damping controllability. The relationships between the selected parameters and applied currents are determined by curve fitting. Genetic algorithm (GA) and pattern search (PS) are used to identify parameter values of the MR damper models. A modified Bouc–Wen model is considered and its parameters are obtained using these methods. Then the experimental data with different frequencies, amplitudes, and currents are used to verify the proposed SPAM. The results show that the simulation data agree well with the measured experimental data. Compared with the traditional identification method that relies on assumption and visual inspection, errors produced by SPAM are greatly reduced. At last, Bouc–Wen model and modified Dahl model are considered and analyzed using SPAM.

This study presents the vibration of an adaptive sliding mode fault-tolerant control for MR suspension system considering the partial fault of MR dampers. After formulating a full car dynamic model featuring four MR dampers, the fault model of the MR dampers due to the varying working temperature is derived. An adaptive sliding model fault-tolerant control strategy is then proposed after the occurrence of a fault. The performance of the proposed control scheme is evaluated and compared under the bump road condition and presented in time domain. The results show that significant gains are made in the presence of the partial fault of an MR damper. The control scheme could reduce the effect of the partial fault of the MR damper on system performance.

An experimental study is conducted with the intention of identifying the dynamics of a magnetorheological (MR) damper incorporated with a steel beam structure and evaluating the efficiency of the formulated forward and inverse dynamic models for online application of semiactive vibration control. A hybrid modeling method by synthesizing NARX (non-linear autoregressive with exogenous inputs) model and neural network technique within a Bayesian framework is developed to figure out the forward and inverse dynamics of the MR damper from real-time experimental data. The forward dynamic model has the ability to predict the one-step-ahead damper force, while the inverse one is able to estimate the current/voltage command for the MR damper. To evaluate the implementability of the formulated models for online application, semiactive control experiments are performed on the beam structure incorporating the MR damper. The forward model is integrated into a LQR-based semiactive controller to estimate the instant damper force limitation for the semiactive constraint decision, and the inverse model is synthesized to determine current command for the MR damper to track the desirable control force, which compensates for the intrinsic hysteresis effect of the MR damper. The experimental results demonstrate considerably accurate prediction capability and practicability of the Bayesian NARX network models for the MR damper, and the effectiveness of the semiactive controller accommodating the forward and inverse dynamics of the MR damper for structural vibration mitigation.

This article presents a novel haptic interface for rehabilitation purposes using MR-dampers. In the rehabilitation, patients are required to do certain exercises to train damaged muscles. Specialized devices are required to ensure patients will do the exercise accurately. Typical devices that are used for this application are difficult to program and may cause damage by applying excessive force to human body. The haptic device that is designed in this article will address the issues by employing MR-dampers and a user-friendly programming methodology. The concept of Resistive-Map generation is introduced as main strategy for activating MR-dampers and restricting the motion to the regions determined by the therapist. To simulate the performance of the system, an accurate model of MR-damper is obtained and validated experimentally. To test the performance of the proposed MR-based haptic device, the resistance-maps are first generated. MR-dampers are activated according to the positions of the MR-dampers in the resistance-map. The system is also simulated in MATLAB ®/ SimMechanics. The experimental and simulation results are in good agreement. The promising results of the proposed haptic interface make it a potential candidate for rehabilitation applications. Patients will be able to take the device home and the physiotherapists can online programme the exercises and monitor the performance of patients.

In order to make the best compromise between the damping force and the linearity of the integrated relative displacement sensor (IRDS) of an integrated relative displacement self-sensing magnetorheological damper (IRDSMRD), a Pareto optimization-based method, which optimizes the key structural parameters by taking the damping force and the linearity of the IRDS of the IRDSMRD as the objective functions, is proposed and realized in this article. The Pareto front, representing the best tradeoff between the damping force and the linearity of the IRDS of the IRDSMRD, is obtained by considering that the maximum magnetomotive force applied to the exciting coil of the IRDSMRD is constant. Three IRDSMRDs with different piston modules, which are determined according to the Pareto optimal solutions, are developed and tested. The research results indicate that every point on the Pareto front is an optimal solution that compromises the damping force and the linearity of the IRDS of the IRDSMRD and the optimal damping force of the IRDSMRD with a certain linearity of the IRDS as well as the optimal linearity of the IRDS with a certain damping force can be determined according to the Pareto front for a specific application.

Utilizing the integration by parts rule, a simple and general computational method is proposed for solving quasi-steady parallel plate flow problems and most types of fluids can be handled by this method, such as the Newtonian fluid, the Power-law fluid, the Bingham fluid, and the Herschel-Bulkley fluid. The flow rate-pressure gradient relation for quasi-steady parallel plate flows is derived based on an abstract piecewise constitutive equation. Moreover, the flow rate is directly expressed in terms of the constitutive equation in this method, so high efficiency is achieved. As an application example of the proposed method, a new quasi-steady magnetorheological damper model more general than the existing ones is developed with the material non-linearities considered in both the pre-yield and post-yield regimes. Finally, conversions of this model to the Bingham model, the Herschel-Bulkley model, the Biviscous model, etc., are demonstrated.

The use of magnetorheological (MR) dampers for mitigating vibrations caused by seismic motions in civil engineering structures has attracted much interest in the scientific community because of the advantages of this class of device. It is known that MR dampers can generate high damping forces with low energy requirements and low cost of production. However, the complex dynamics that characterize MR dampers make difficult the control design for achieving the vibration reduction goals in an efficient manner. In this article, a semiactive controller based on the backstepping technique is proposed. The controller was applied to a three-story building with an MR damper at its first floor subjected to seismic motions. The performance of the controller was evaluated experimentally by means of real time hybrid testing.

Magnetorheological (MR) dampers are promising devices for vibration mitigation in structures due to their low cost, energy efficiency, and fast response. To use these dampers efficiently it is necessary to have models that describe their behavior with a sufficient precision. However, because a precise modeling of these devices using the laws of physics is an arduous task, semi-physical models are used to describe their behavior instead. Two of these models are explored in this article: a normalized version of the Bouc-Wen model and the Dahl friction model. A methodology for identification is proposed, and the obtained models are tested and validated experimentally.

Magnetorheological (MR) dampers can experience large temperature changes as a result of heating caused by energy dissipation, but control systems are often designed without consideration of this fact. Furthermore, due to the highly nonlinear behavior of MR dampers, many control strategies have been proposed and it is difficult to determine which is the most effective. This paper aims to address these issues through a numerical and experimental study of an MR mass isolator subject to temperature variation. A dynamic temperature dependant model of an MR damper is first developed and validated. Control system experiments are then performed using hardware-in-the-loopsimulations. Proportional, PID, gain scheduling, and on/ off control strategies are found to be equally affected by temperature variation. Using simulations incorporating the temperature dependant MR damper model, it is shown that this is largely due to a change in fluid viscosity and the associated movement of the lower `clipped optimal' control bound. This zero-volts condition determines how close any controller can perform to the ideal semiactive case, thus all types of controller are affected. In terms of relative performance, proportional and PID controllers perform equally well and outperform the on/off and gain scheduling strategies. Gain scheduling methods are superior to on/off control.

This study presents an electromagnetic design methodology for the magnetorheological (MR) damper. To improve the performance of the MR damper, the magnetic field should be effectively supplied to the MR fluid. Therefore, it is important that the magnetic circuit composed with the MR fluid, the ferromagnetic yoke for forming the magnetic flux path, and the electromagnetic coil are well designed from the electromagnetic viewpoint. For this purpose, two effective approaches are proposed; one is to shorten the magnetic flux path by removing the unnecessary bulk of the yoke in order to improve the static characteristic of the MR damper, and the other is to increase the magnetic reluctance of the magnetic circuit by minimizing the cross-sectional area of the yoke through which the magnetic flux passes in order to improve the dynamic and hysteretic characteristics. After designing and manufacturing two MR dampers, the conventional type and the proposed type, their performances are evaluated and compared through the magnetic field analysis and a series of basic experiments. These results show that the proposed design methodology can be effectively used as a fundamental design material for expanding application fields of the MR damper.

Quasisteady modeling of linear stroke flow mode magnetorheological (MR) (or electrorheological (ER)) dampers has focused primarily on the utilization of the Bingham-plastic constitutive model to assess performance metrics such as damping capacity. In such Bingham-plastic MR (or ER) flows, the variable yield stress of the fluid, τy, is activated by applying magnetic (or electric) field. The Bingham-plastic model assumes that the material is in either (1) a pre-yield condition where the local shear stress is less than the yield stress, τy, or (2) a post-yield condition, where the local shear stress is greater than the yield stress, τ > τ y, so that the material flows with a constant post-yield viscosity. The objective of this study is to analyze the damping capacity of such a controllable MR or ER damper in the situation when the field dependent fluid exhibits post-yield shear thinning or thickening behavior, that is, the post-yield viscosity is a function of shear rate. A Herschel—Bulkley model with a field dependent yield stress is proposed, and the impact of shear rate dependent viscosity on damping capacity is assessed. Key analysis results — velocity profile, pre-yield thickness, and damping coefficient — are presented in a nondimensional formulation that is consistent with prior results for the Bingham-plastic analysis. The nondimensional analysis formulated here clearly establishes the Bingham number as the independent variable for assessing flow mode damper performance.