Electrorheological Damper Research Articles

AI vibration control of high-speed rotor systems using electrorheological fluid

This paper is concerned with the design and application of an electrorheological (ER) fluid damper to semiactive vibration control of rotor systems. In particular, the system under the present study is constructed structurally flexible in order to explore the behavior of a high-speed spindle system traversing multiple critical speeds within motor capacity. To seek a way of suppressing the rotor vibration, dynamic models for the proposed ER damper and its associated amplifier are derived. Subsequently, they are assembled with the other relevant spindle components by means of the finite element method, enabling predictions as to free and forced vibration characteristics of the entire rotor system. Next, an artificial intelligent (AI) feedback controller is synthesized based on the system model, taking into account the stiffening effect of the point damper in flexible rotor applications. Finally, computational and experimental results are presented regarding model validation and control performances. In practice, such an AI control scheme proves effective and robust whether the spin rate is either below or above the critical speeds.

Signal frequency-based semi-active fuzzy control for two-stage vibration isolation system

In this paper, a novel feed forward control scheme with a fuzzy controller, based on the identification of the signal's main frequency, is proposed to control a semi-active two-stage vibration isolation system such as the floating raft isolation system, whose excitation signal changes regularly. A fuzzy controller is employed in this method to achieve the best isolation effect by analyzing the main frequency's characteristics of the excitation signal, such as amplitude and position, and a bypass electro-rheological (ER) damper is applied to achieve the best control effect more rapidly and accurately. The inputs of the fuzzy controller are the characters of the signal's main frequency and the output is the effect coefficient of the main frequency. Then, the optimal damping ratio of the ER damper and the appropriate voltage could be obtained. The experimental results indicate that the proposed feed forward control method is more effective in vibration isolation in comparison with the passive optimal system.

A Two-Stage Vibration Isolation System Featuring an Electrorheological Damper via the Semi-Active Static Output Feedback Variable Structure Control Method

In this paper, we present a semi-active static output feedback variable structure control (VSC) strategy for vibration isolation. The control concept is based on the fact that, for a practical vibration isolation system subject to external disturbances, all state variables are hard to measure on-line and variations of system parameters frequently exist. A bypass electrorheological (ER) damper is designed and manufactured by incorporating a Bingham model of ER fluids. After the voltage-dependent damping characteristics of the ER damper are evaluated, the dynamic model of a two-stage vibration isolation system with one ER damper is derived. Using only the measured information from sensors installed at strategic locations, continuous output feedback VSC controllers are presented, which do not have possible chattering effects. The continuous control law is decoupled from external disturbances by combining controller design under a meeting sliding mode reachable condition with the choice of sliding surface gradient parameters under a guarantee of the Routh-Hurwitz stability of reduced-order sliding mode dynamics. The saturation of the actuator is also incorporated into the controller, showing no adverse effect. The self-adaptability of the vibration isolation system with respect to external disturbances, the robustness of the control method with respect to parameter variations and the effectiveness of vibration isolation are demonstrated by numerical simulation results in the frequency and time domains. It is illustrated that the performance of the presented semi-active static output feedback VSC system is superior to those of optimally passive damping and maximum damping variety even if system parameter uncertainties exist.

A unified modelling and model updating procedure for electrorheological andmagnetorheological vibration dampers

Magnetorheological (MR) and electrorheological (ER) dampers are known to exhibitnonlinear behaviour which can make it difficult to predict their performance, particularlywhen they are integrated into engineering structures. As a result it can be impossible toproperly assess the feasibility of using such semi-active devices to solve practicalengineering problems.In this paper, a new model format is proposed which represents an extension of earlier workby the authors. The proposed model is more general and yet maintains the physicalsignificance of key parameters. A novel model updating (or system identification)technique is developed so that the model can account for the behaviour of variousconfigurations of device without the need for prior knowledge of the fluid properties. Thetechnique relies upon the iterative adjustment of the model’s stiffness parameterso that the quasi-steady behaviour of the device can be estimated. Correlationbetween a bi-viscous model and the estimated quasi-steady behaviour is used as thecriterion for choosing the most suitable value of stiffness. The modelling technique iscompleted by establishing empirical shape relationships between the pre-yieldparameters, post-yield parameters, yield force and the applied excitation conditions.The modelling and identification procedures are applied to an MR damping device and theresults are validated by comparing predicted and experimental responses under bothnon-sinusoidal and broadband excitation conditions.

Non-dimensional analysis for effective design of semi-active electrorheological damping control systems

This paper presents a non-dimensional analysis for effective design of semi-active electro- rheological (ER) damping control systems. The non-dimensional equations consist of the Bingham number, the non-dimensional damping force, the dynamic range and the non-dimensional geometric parameter. After showing the effectiveness of the proposed analysis scheme through a comparative examination of predictions and measured values of the non-dimensional damping force, sequential steps for the ER damper design have been developed. A flow mode type ER damper, considering control performance of a semi-active quarter-car system, has been designed on the basis of the proposed non-dimensional design steps. To assess the effectiveness of the proposed non-dimensional design methodology, the field-dependent damping forces of an ER damper have been experimentally evaluated and compared with those obtained from the non-dimensional analysis.

Mechatronics design of stiffness enhancement of the feed supporting system for the square-kilometer array

Design and implementation of stiffness enhancement of a feed supporting system for the square-kilometer array (SKA) using electrorheological (ER) variable damper is presented in this paper. The feed supporting system consists of a large parallel cable manipulator and a fine-tuning Stewart platform. Hence, the feed supporting system is a large delay system and sensitive to the influence of wind. Furthermore, the adjustment of the fine-tuning Stewart platform will affect the coarse tracking control. Therefore, in order to suppress these disturbances and realize the independent control of the two parallel manipulators, it is necessary to enhance the stiffness of the feed supporting system. The proposed ER variable damper is designed and directly attached to the shaft of the servomotor of the feed supporting system to achieve high servo stiffness and trajectory tracking accuracy. The model of the feed supporting system is first derived, the structure of the variable-viscous ER damper is presented, and then the damping coefficient model is developed. The validation of this stiffness enhancement design of the feed supporting system is demonstrated with position PD control of the feed supporting system. This result has built a solid base for the accomplishment of the high-accuracy requirement of the SKA.

Study on theoretical modeling of semi-active electro-rheological fluid damper

This paper emphases on analyzing and investigating the mechanical behavior of electro-rheological fluid (ERF) semi-active damper. Theoretical model was developed to describe the relationship between electric field and the resistance force of ERF flowing through two parallel plane electrodes. In the model, the pressure drop along electrodes was supposed to consist of two parts: one related with viscosity and the other related with dynamic yield shear stress. The concept of yield stress influence factor was developed in deriving the theoretical formula for calculating the pressure drop in the damper. The influences of some other factors, such as, non-ideal Newtonian fluid and temperature have also been taken into account. Numerical and experimental work have been performed to prove the validity of the proposed model. The comparison of both results shows that the developed model is quite effective and practicable.

Design and performance research of an adaptive damper composed ofelectrorheological fluids and piezoelectric ceramics

A new kind of adaptive damper composed of electrorheological (ER) fluids andpiezoelectric ceramics is proposed in this paper. Its feature is that piezoelectricceramics respond to outside vibrations and provide an electric field to solidify theER fluid in the damper so that the auto-adjustment of damping is realized.According to the change of the frequency and amplitude of the outside vibrations,the response of an ER fluid changes and the adaptive control of vibration isrealized. Compared with ordinary ER dampers, there is no high voltage sourcesand computer control equipment in the damper system. The computersimulation shows that the vibration suppression effect of the damperincreases with the stimulating force, but the vibration suppression effectdecreases when the stimulating frequency increases. In the test of thedamper’s performance we observe manifest vibration suppression results.

A method for determining locations of electro-rheological dampers instructures

This paper develops an effective procedure for determining the locations of theelectro-rheological (ER) dampers in complex structures. Using virtual dampersplaced at the locations of interest in systems, the power dissipation of thevirtual dampers can be computed. On the basis of the values of the powerdissipation for virtual ER dampers placed at different positions, the searchprocedure for finding the best locations for ER dampers is discussed.In order to illustrate the control effect of ER dampers on vibrations ofstructures, non-linear response analysis is also discussed, with local modesuperposition. A numerical example—an automotive chassis with ERdampers—is treated, to illustrate the application of the present theory.

Comparison of damping force models for an electrorheological fluid damper

In this work, five different models are proposed to predict the field-dependent damping force of an electrorheological (ER) damper and are compared. These are: the Bingham plastic model, the hysteretic Bingham plastic model, the hysteretic biviscous model, the Bouc-Wen model and the hydro-mechanical model. After briefly describing the inherent characteristics of each model, model parameters are identified using a set of experimental data that are obtained by changing electric fields and excitation frequencies. The identified parameters are analysed and used to reconstruct the damping force – the piston velocity plot that directly indicates the hysteresis behaviour of the ER damper and compared with the measured hysteresis loop. In addition, the damping force error between the prediction and experiment is evaluated for each model.

H∞ control of electrorheological suspension system subjected to parameter uncertainties

Vehicle suspension is normally used to attenuate unwanted vibration from various road conditions. The successful suppression of the vibration leads to the improvement of ride comfort as well as steering stability of the vehicle. One of attractive candidates to formulate successful vehicle suspension is to use electrorheological (ER) damper. This paper presents robust control performances of ER suspension system subjected to parameter uncertainties associated with sprung mass of the vehicle and time constant of the ER damper. After identifying dynamic bandwidth of a cylindrical ER damper operated with two different ER fluids (one has fast response characteristic, while the other slow response characteristic), a quarter car model is established by incorporating with time constant of the damping force. A robust H ∞ controller, which compensates the sprung mass and time constant uncertainties, is designed in order to suppress unwanted vibration of the vehicle. Control responses such as vertical acceleration of the sprung mass are presented in time and frequency domains. In addition, the effect of time constant of the damping force on the vibration control performance is investigated by undertaking a comparative work between fast and slow dynamic characteristics of the ER damper.

The wind-induced vibration control of feed supporting system for large spherical radio telescope using electrorheological damper

Considering the wind-induced vibration of the feed supporting system with cables for the optomechatronics design project of next generation large spherical radio telescopes, a prototype of adaptive electrorheological (ER) damper is designed to realize additional damping control of this vibration. The model of wind is first developed to implement this design and simulations. The model of the designed ER adaptive damper is described in detail, and the strategy of additional damping control using the controllable field-dependent damping force of the ER damper to counteract the wind force is proposed. The numerical simulation results have shown the validity of the designed adaptive ER damper to suppress the wind-induced vibration of the feed supporting system, and the additional damping vibration amplitude can be suppressed to one-half of the original amplitude without ER damper.

Mechatronics design of response enhancement of Stewart fine tuning platform for the square kilometer array

For the rapid response requirement of the trajectory tracking of the next generation large radio telescope-square kilometer array (SKA), a mechatronics design strategy using homogeneous electrorheological (ER) damper to enhance the response of Stewart fine tuning platform is proposed in this paper. The viscosity-variable homogeneous ER damper is directly attached on the ram of the linear actuator to tune the additional damping of the actuator controlled system, so that the large gain coefficient can be used to enhance the response of Stewart fine tuning platform. The position PD controller design methodology is proposed based on this mechatronics strategy using conventional pole assignment technique, and the relationship between the ER damping coefficient and the bandwidth of linear actuator control system is presented. The simulation results have verified the effectiveness of this mechatronics design strategy, the designed controlled actuator system based on this mechatronics strategy has large gain coefficient and favorable performance over the conventional designed one, which have laid a solid base for the engineering implementation of the SKA.

Electrorheological Damper Analysis Using an Eyring Constitutive Relationship

We validate and assess the applicability of an Eyring constitutive model. The Bingham plastic model has a zero shear rate discontinuity, which leads to inaccuracies in modeling and simulation, and is characterized by two rheological constants for a constant field: yield stress and postyield viscosity. The Eyring model has a smooth transition through the zero shear rate condition, and also has two rheological constants for a constant field. An electrorheological (ER) damper having a damping level comparable to a shock absorber for a small-sized passenger car damper is manufactured, and its performance is predicted using the Eyring model. To accurately identify the rheological parameters of the Eyring model, a parameter identification method was used. The damping force versus piston displacement and velocity behaviors of the ER damper are experimentally measured with respect to applied electric field and excitation frequency. To validate the Eyring model, the experimental results are compared with predictions in the damping force versus piston displacement and velocity behaviors.

Vibration Control Evaluation of a Commercial Vehicle Featuring MR Seat Damper

This paper presents vibration control responses of a commercial vehicle installed with electro-rheological (ER) primary suspensions and a magneto-rheological (MR) seat damper. After formulating the governing equation of motion of the full-vehicle system associated ER and MR dampers, the sky-hook controllers are designed by imposing semi-active actuating conditions. The control algorithms are then implemented via the hardware-in-the-loop simulation, and control responses of vertical displacement and acceleration at the driver’s seat are evaluated under two road conditions; bump and random road.

SYNTHESIS AND ELECTRORHEOLOGY OF PHOSPHATE CELLULOSE SUSPENSIONS

As a candidate for the development in electrorheological (ER) materials, phosphate cellulose (PC) particles were synthesized from the phosphate–ester reaction between cellulose particles and ammonium phosphate solution prepared from six different molar concentrations of phosphoric acid. The synthesized particles were then dispersed in silicone oil to prepare the PC-based anhydrous ER fluid. The effects of electric field strength and particle concentration on the ER performance were investigated with both steady shear and dynamic oscillatory shear modes. The ER system with PC particles formed with a 2 M phosphoric acid solution exhibited the highest yield stress. A difference in the flow behavior of the PC-based ER fluids was also analyzed via the dielectric spectra using an impedance analyzer. We adapted the PC-based ER fluids to the semi-active ER damper and the examined their damping characteristics.

Comparative Analysis of the Time Response of Electrorheological and Magnetorheological Dampers Using Nondimensional Parameters

Electrorheological (ER) and magnetorheological (MR) fluids show similar field-dependent rheological characteristics from a bulk fluid perspective. However, the implementation of ER and MR fluids in devices may require different strategies because of the inherent properties of ER and MR fluids such as density, viscosity and the magnitude of the yield stress. Therefore, in this study, we explore the characteristics of ER and MR fluid-based systems on the basis of dynamic range and time response in order to comprehensively understand each system. In doing so, a nondimensional analysis, based on parallel plate geometry, is used to characterize the field-dependent properties of ER and MR fluid-based dampers. Experimental tests are conducted for ER and MR dampers in order to validate our analysis.

Electrorheological Semi-Active Damper: Polyaniline Based ER System

Among various materials suitable for an electrorheological (ER) fluid, polyaniline and its many derivatives based upon modification of oxidation state, dopant and polymerization conditions are of technological interest for their adaptation into ER fluids. This is because they have better thermal stability and smaller density than other potential ER materials. Furthermore, polyaniline is easy to polymerize by oxidation polymerization at relatively low temperature and can be doped from a conducting emeraldine hydrochloride form to an insulating state using simple protonic acids. In this study, we adapted the polyaniline based ER fluids for semi-active cylindrical flow-mode type ER damper. A cylindrical flow-mode type ER damper was chosen in this study because it has similar geometrical configuration to the conventional damper normally used for passenger vehicle. The damping forces measured using a semi-active ER damper with polyaniline based ER fluids were found to be controlled by tuning an applied electric field for different piston velocity.

ER 유체 감쇠기를 이용한 유연 회전축 계의 진동제어

This paper concerns the design and application of an electro-rheological (ER) fluid damper to semiactive vibration control of rotor systems. In particular, the system under present study is constructed structurally flexible in order to explore multiple critical speeds within operation range. To this end, the dynamic models of the proposed ER damper and its associated amplifier are derived in the first place. Subsequently entire rotor system model is assembled along with the dynamics of the end effector based on a finite element method enabling prediction as to its free and forced vibration characteristics. Next, an artificial intelligent (AI) feedback controller is synthesized taking into account the peculiarity of Coulomb damping effect in rotor applications. Finally, computational and experimental results are presented including model validation and control performances. In practice, such an AI control proved effective whether the spin speed was either before or after critical speeds.

Nonlinear Frequency Spectrum Analysis of Vibration System with ER Damper

The Electro-rheological (ER) fluid is a new kind of smart material which has been applied to various engineering problems. Using the viscous and bilinear hysteretic damping model, this paper discusses the nonlinear frequency spectrum by iterative perturbation method for nonlinear vibration system with ER damper. Iterative perturbation is based on the matrix perturbation. The initial frequencies are found by subspace iteration. The subsequent frequency spectrum of nonlinear states, which is based upon the tangent stiffness of the structure, is calculated by the iterative perturbation method. A numerical example is given to illustrate the method presented by this paper.