Showing papers on "Magnetorheological damper published in 2015"

Robust force tracking control scheme for MR dampers

Abstract: SUMMARY This paper describes a novel force tracking control scheme for magnetorheological (MR) dampers. The feed forward, which is derived by a control-oriented mapping approach to reduce modelling effort of the inverse MR damper behaviour, compensates for the main steady-state nonlinearity of the MR damper force and thereby linearizes the plant. The resulting force tracking error due to model imperfections and parameter uncertainties is reduced by parallel proportional and integral feedback gains that are formulated based on the absolute values of actual MR damper force and desired control force due to the semi-active constraint of the MR damper force. The feedback is enriched by an anti-reset windup to account for MR damper current constraints and the concept of current reversal to accelerate demagnetization. The experimental validations of the force tracking control scheme on a rotational and a long-stroke MR damper demonstrate its robustness and efficacy. Copyright © 2015 John Wiley & Sons, Ltd.

Design and novel type of a magnetorheological damper featuring piston bypass hole

Abstract: This work proposes a novel type of magnetorheological (MR) damper configuration from which an excellent ride comfort can be achieved without using a sophisticated controller scheme. The proposed novel MR damper is featured by piston bypass holes to achieve low slope of the damping force in the pre-yield (low-piston-velocity) region and high magnitude of the damping force in the post-yield (high-piston-velocity) region. A mathematical model for the damping force of the proposed MR damper is formulated followed by the investigation on damping characteristics with respect to several geometrical design parameters such as the number of piston bypass hole, the diameter of the hole, the gap size of the orifice, the orifice length, the diameter of the bobbin, and the height of the coil. After selecting the main design parameters from the simulation results, numerical simulations for the damping force characteristics are conducted with eight design parameter sets to evaluate the significant effect on the damping force performance. The proposed MR dampers are then manufactured with the same design parameter sets and the damping force characteristics are experimentally obtained and compared with the analytical simulation results. It is identified from the parametric investigations that the size and the number of the piston bypass hole are very important on damping force characteristics of the proposed MR damper.

Nonparametric modeling of magnetorheological elastomer base isolator based on artificial neural network optimized by ant colony algorithm

Abstract: 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 mode...

Design of magnetorheological damper with short time response

Abstract: 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 importan...

Maximizing semi-active vibration isolation utilizing a magnetorheological damper with an inner bypass configuration

Abstract: A single-degree-of-freedom (SDOF) semi-active vibration control system based on a magnetorheological (MR) damper with an inner bypass is investigated in this paper. The MR damper employing a pair of concentric tubes, between which the key structure, i.e., the inner bypass, is formed and MR fluids are energized, is designed to provide large dynamic range (i.e., ratio of field-on damping force to field-off damping force) and damping force range. The damping force performance of the MR damper is modeled using phenomenological model and verified by the experimental tests. In order to assess its feasibility and capability in vibration control systems, the mathematical model of a SDOF semi-active vibration control system based on the MR damper and skyhook control strategy is established. Using an MTS 244 hydraulic vibration exciter system and a dSPACE DS1103 real-time simulation system, experimental study for the SDOF semi-active vibration control system is also conducted. Simulation results are compared to experimental measurements.

Adaptive model-based tracking control for real-time hybrid simulation

Abstract: Model-based feedforward–feedback tracking control has been shown as one of the most effective methods for real-time hybrid simulation (RTHS). This approach assumes that the servo-hydraulic system is a linear time-invariant model. However, the servo-control closed-loop is intrinsically nonlinear and time-variant, particularly when one considers the nonlinear nature of typical experimental components (e.g., magnetorheological dampers). In this paper, an adaptive control scheme applying on a model-based feedforward–feedback controller is proposed to accommodate specimen nonlinearity and improve the tracking performance of the actuator, and thus, the accuracy of RTHS. This adaptive strategy is used to estimate the system parameters for the feedforward controller online during a test. The robust stability of this adaptive controller is provided by introducing Routh’s stability criteria and applying a parameter projection algorithm. The tracking performance of the proposed control scheme is analytically evaluated and experimentally investigated using a broadband displacement command, and the results indicates better tracking performance for the servo-hydraulic system can be attained. Subsequently, RTHS of a nine-story shear building controlled by a full-scale magnetorheological damper is conducted to verify the efficacy of the proposed control method. Experimental results are presented for the semi-actively controlled building subjected to two historical earthquakes. RTHS using the adaptive feedforward–feedback control scheme is demonstrated to be effective for structural performance assessment.

Semi-active control of isolated and damaged structures using online damage detection

Abstract: The idea of using semi-active or active control devices within a base isolation system has been developed recently, since applying this system to building structures has some shortcomings such as the creation of large displacements at the base level and the systemʼs lack of adaptability to different seismic excitations. In this study, an integrated structural health monitoring and semi-active control scheme is proposed to enhance the seismic behavior of damaged isolated structures. The nonlinear behavior of an isolated structure is limited to the isolator level and the superstructure is assumed to remain linear. Then, using an online damage detection algorithm based on identified system Markov parameters and a semi-active fuzzy controller, the damage in the base isolator is mitigated and the seismic response of the structure is reduced. In addition, a magnetorheological damper is utilized as a well-studied semi-active actuator in the control system. The effectiveness of the proposed control system is evaluated through the numerical study of a six-degrees-of-freedom model of base-isolated buildings excited by various near-fault and far-field earthquake records. The results of the simulation show that the integrated algorithm is substantially effective in improving the dynamic behavior of isolated structures and reducing the damage in the isolator.

Design and development of a novel displacement differential self-induced magnetorheological damper

Abstract: 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 dis...

Limiting factors of the response time of the magnetorheological damper

Abstract: Magnetorheological dampers seem to be suitable for the adaptive car suspension systems. For proper operation of the semi-active algorithms (skyhook, groundhook), the force response of the damper must be fast enough. In this paper, the response time of the Delphi vehicle MR damper is examined and the sources of the overall force time response on the control voltage are discussed. One of the main sources of the response time seems to be electro-magnetic circuit of the MR damper. A principle of an optimal controller for reducing response of the coil's current on the control voltage is designed. However, the measured overall force time response with fast current controller was not reduced as expected. Therefore, a FEM simulation of the magnetic circuit was made. It shows that after an optimization of the current controller, eddy currents in the coil's core cause long time response and therefore they are the limiting factor of the response time of the MR damper. These simulations were verified by the measurements and some recommendations about improving the pistons construction are given at the end.

A Lumped-Parameter Model for Adaptive Dynamic MR Damper Control

Abstract: The dynamic behavior of a small-scale magnetorheological damper intended for use in a tremor-suppression orthosis is characterized through experimental analysis and mathematical modeling. The combined frequency response of both the electromagnetic coil and the fluid particles is modeled by a third-order transfer function. The output of this function is an effective current that, combined with piston position and velocity, is empirically related to the resistance force of the damper. The derived model demonstrates high-fidelity to experimental testing of the damper under variable piston velocity and applied current within the expected frequency range of pathological tremor. The model is, thus, deemed suitable for use in a control algorithm for the mechanical suppression of tremor via magnetorheological damping.

Static and Dynamic Experiment Evaluations of a Displacement Differential Self-Induced Magnetorheological Damper

Abstract: This paper presents the development of a novel magnetorheological damper (MRD) which has a self-induced ability. In this study, a linear variable differential sensor (LVDS) based on the electromagnetic induction mechanism was integrated with a conventional MRD. The structure of the displacement differential self-induced magnetorheological damper (DDSMRD) was developed, and the theory of displacement differential self-induced performance was deduced. The static experiments of the DDSMRD under different displacement positions were carried out by applying sine excitation signals to the excitation coils, and the experimental results show that the self-induced voltage is proportional to the damper piston displacement. Meanwhile, the dynamic experiments were also carried out using the fatigue test machine to investigate the change of the self-induced voltage under the typical direct current inputs and the different piston rod displacements; the experimental results also show that the self-induced voltage is proportional to the damper piston displacements. Additionally, the dynamic mechanical performance of the DDSMRD was evaluated. The theory deduction and the experimental results indicate that the proposed DDSMRD has the ability of the integrated displacement sensor in addition to the output controllable damping force.

A new magnetorheological damper with improved displacement differential self-induced ability

Abstract: This work is an extension of our previous study on the development of a linear variable differential sensor (LVDS)-based magnetorheological (MR) damper with self-sensing capability, where a new MR damper integrated with LVDS technology was developed and prototyped, then its self-induced performance under static and dynamic working conditions was experimentally evaluated. The results of the static and dynamic experiments indicated that the self-induced voltage was proportional to the displacement of the damper. Moreover, the damping performance of this new MR damper was also evaluated through an experimental study. Compared with our previous study, the new MR damper performed better in terms of its self-induced sensing ability and damping capacity.

Adaptive control of structures under dynamic excitation using magnetorheological dampers: an improved clipped-optimal control algorithm

Abstract: This paper investigates the performance of magnetorheological (MR) dampers to mitigate the effect of earthquake loading on civil engineering structures. MR dampers are semi-active fluid dampers con...

Experimental Identification of a Self-Sensing Magnetorheological Damper Using Soft Computing

Abstract: This paper presents the development and application of a soft-computing technique in identification of forward and inverse dynamics of a self-sensing magnetorheological (MR) damper based on experimental measurements. This technique is developed by the synthesis of an NARX (nonlinear autoregressive with exogenous inputs) model structure and neural network within a Bayesian inference framework. The Bayesian inference procedures essentially eschew overfitting that could occur in network learning and improve generalization (prediction) capability by regularizing the complexity of learning. In applying the developed technique to the self-sensing MR damper, the present and past information of its input and output quantities, which contain the physical knowledge of the damper, is used to formulate its nonlinear dynamics. The NARX network architecture is then optimized to enhance modeling effectiveness, efficiency, and robustness. Experimental data of the damper subjected to both harmonic and random excit...

Thermodynamic Behaviors of a Kind of Self-Decoupling Magnetorheological Damper

Abstract: A theoretical model of temperature change on a kind of self-decoupling magnetorheological (SDMR) damper was established based on conservation of energy, and the constraint equation for structural design parameters of the SDMR damper was improved to satisfy heat dissipation requirements in this work. According to the theoretical model and improved constraint equation, the main structure parameters of SDMR damper were obtained and the damper was tested. The temperature performance test results indicate that the rising temperature makes the damping force decline, and the main affection factors of temperature variation are excitation methods and input current. The results also show that the improved constraint equation and design method introduced are correct and efficient in the engineering.

Variable-stiffness variable-damping shock absorber based on magnetorheological damper

Abstract: The invention discloses a variable-stiffness variable-damping shock absorber based on a magnetorheological damper. The shock absorber is characterized in that an outer cylinder body is glidingly mounted on the outer side of the magnetorheological damper; a spring mounted in the outer cylinder body is connected with the piston rod of the magnetorheological damper; when the magnetorheological damper and the spring vibrate by external pressure, the outer cylinder body slides on the outer side of the magnetorheological damper to change the travel of the whole shock absorber, and meanwhile, the electrification coil of the magnetorheological damper is electrified and the shape of a magnetorheological fluid is changed to change the damping of the shock absorber. According to the shock absorber, the magnetorheological damper is combined with the spring, so that the stiffness and damping of the shock absorber can be changed; the shock absorber is large in travel and can meet the requirements of an environment in need of the shock absorber with large travel.

Semiactive Magnetorheological Damper for High Aspect Ratio Boring Process

Abstract: This paper aims to develop a new semiactive damper to attenuate chatter vibration of a high aspect ratio boring bar. Design of the damper utilizes magnetorheological (MR) fluid and an electromagnet to control a damping force by a current input during machining process so as to effectively attenuate the chatter vibration. Various aspects of research on MR fluid and dynamic characteristics of boring operation and the MR damper have been investigated; First of all, effectiveness of MR fluid on attenuating vibration has been investigated by various designs of the damper and magnetic field. Then, the behavior of the MR fluid is simulated and its result is utilized to estimate dynamic motion of the MR actuator. Furthermore, simulation of the boring tool, force, and stability model shows significant improvement in machine chatter particularly for a high aspect ratio boring bar. The results provide a fundamental understanding to estimate dynamic vibration of the boring bar and offers optimal conditions for effectively attenuating chatter vibration. Finally, various experiments have been demonstrated to identify parameters of the MR damper and the results of boring machining show damper attenuation capability for wide frequency band by various cutting conditions corresponding to chatter frequencies.

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

Abstract: The magnetorheological (MR) damper is one of the utmost progressive applications of asemi-active damper. Uninterrupted controllability in both on and off state is an important factor of its plenitude application. Current research is attempting to make the damper more effective and efficient by minimizing the existing limitations such as MR fluid’s sedimentation, power consumption and temperature rising, and design optimization. We have broadly analyzed the optimization of MR dampers design with finite element simulation where various parameters of the MR damper have been considered for more accurate results. A prototype MR fluid has been prepared by coating the carbonyl iron particles with xanthan gum to reduce sedimentation. The SEM and Turbiscan results noticeably verify the improved sedimentation stability. In addition, a power-saving MR damper model has been developed by finite element analysis using ANSYS software. Prolonged operation raises the damper’s body temperature and degrades the performance. However, in this energy-saving MR damper model the temperature is not rising to a higher value compared to the conventional dampers, and consequently promotes damper efficiency.

Single-rod variable-cylinder-body passive single-control variable-damping magnetorheological damper

Abstract: The invention discloses a double-rod variable-cylinder-body active single-control variable-damping magnetorheological damper and belongs to the field of magnetorheological fluid instruments with the variable-damping structure vibration reduction function. The magnetorheological damper comprises a working cylinder body module, two end cover modules, two piston modules, a working clearance and a power source. The working cylinder body module comprises a gradient internal diameter working cylinder, a coil arranged on the outer wall of the gradient internal diameter working cylinder, and an electric field shielding layer arranged outside the coil. The gradient internal diameter working cylinder is a hollow cylinder, wherein the internal diameters of the two ends of the gradient internal diameter working cylinder are minimal, the internal diameter of the middle of the gradient internal diameter working cylinder is maximal, and the internal diameters of the other portions linearly change along the axis of the gradient internal diameter working cylinder. The working clearance for magnetorheological fluid is formed between the outer circumferential walls of pistons and the inner circumferential wall of the gradient internal diameter working cylinder. The volume of the working clearance linearly changes along the axis position. The magnetorheological damper is reasonable in structure and larger in damping force adjusting range, and damping is controlled through the gradually-changing working clearance and a gradually-changing magnetic field.

Magnetic circuit design and computation of a magnetorheological damper with exterior coil

Abstract: Magnetorheological damper becomes an active damping control method. It was focused on the research of double cylinder damper with interior coils. The main working modes were analyzed. There were some engineering shortages, such as sealing, heat radiation, greater volume, power supply in the traditional MR damper products. A kind of magnetorheological damper with exterior coils was researched. Reasonable layout and parameters were important design factors to require enough magnetic field density with less power loss. So the damper adopt two coils and three magnetic yokes in magnetic design, and worked at the mixed shear valve mode. Magnetic field theoretical computation processes were described and some key parameters were provided. The results of the COMSOL demonstrated the theoretical validation. At last, a 3D assembly drawings was shown, in which the interior volume compensation design method was introduced.

Regenerative magnetorheological dampers for vehicle suspensions

Abstract: Magnetorheological (MR) dampers are promising for vehicle suspensions, by virtue of their adaptive properties. During the everyday use of vehicles, a lot of energy is wasted due to the energy dissipation by dampers under the road irregularities. On the other hand, extra batteries are required for the current MR damper systems. To reduce the energy waste and get rid of the dependence on extra batteries, in this paper, regenerative MR dampers are proposed for vehicle suspensions, which integrate energy harvesting and controllable damping functions. The wasted vibration energy can be converted into electrical energy and power the MR damper coil. A regenerative MR damper for vehicle suspensions is developed. Damping force and power generation characteristics of the regenerative MR damper were modeled and analyzed. Then the damper is applied to a 2 DOF suspension system for system simulation under various road conditions. Simulation results show that riding comfort can be significantly improved, while harvesting energy for other use in addition to supply power for the controlled MR damper.

Adaptive Vibration Control System for MR Damper Faults

Abstract: Several methods have been proposed to estimate the force of a semiactive damper, particularly of a magnetorheological damper because of its importance in automotive and civil engineering Usually, all models have been proposed assuming experimental data in nominal operating conditions and some of them are estimated for control purposes Because dampers are prone to fail, fault estimation is useful to design adaptive vibration controllers to accommodate the malfunction in the suspension system This paper deals with the diagnosis and estimation of faults in an automotive magnetorheological damper A robust LPV observer is proposed to estimate the lack of force caused by a damper leakage in a vehicle corner Once the faulty damper is isolated in the vehicle and the fault is estimated, an Adaptive Vibration Control System is proposed to reduce the fault effect using compensation forces from the remaining healthy dampers To fulfill the semiactive damper constraints in the fault adaptation, an LPV controller is designed for vehicle comfort and road holding Simulation results show that the fault observer has good performance with robustness to noise and road disturbances and the proposed AVCS improves the comfort up to 24% with respect to a controlled suspension without fault tolerance features

Theoretical study of a twin-tube magnetorheological damper concept

Abstract: In this study, the author presents a theoretical model of a semi-active magnetorheological (MR) twin-tube damper concept. The model relies on geometric variables and material properties and can be used in engineering and research studies on damper structures. Other non-linear characteristics, namely, the fluid chamber compressibility, fluid inertia, cylinder elasticity, friction, one-way check valves are included into the model as well. The author studies the performance of the damper model as design variables are varied, and the results are analysed and discussed.

A 2D Mathematical Model of a Short Magnetorheological Squeeze Film Damper Based on Representing the Lubricating Oil by Bilinear Theoretical Material

Abstract: Unbalance is the principal source of excitation of lateral vibrations of rotors and of increase of the time varying forces transmitted to the rotor casing. These undesirable effects can be reduced if the damping devices are inserted between the rotating and stationary parts. To achieve their optimum performance in a wide range of rotational speeds their damping force must be adaptable to the current operating conditions. This is offered by application of magnetorheological damping elements. To learn more on their properties a new 2D mathematical model of a short magnetorheological squeeze film damper has been developed and is presented here. The model is based on representing the magnetorheological oil by bilinear material whose flow curve is continuous unlike to the models based on Bingham or Herschel-Bulkley theoretical fluids. This reduces the nonlinear character of the motion equations and increases computational stability of the procedures used for their solving which was confirmed by the performed computational simulations. In addition, behaviour of the developed model of the squeeze film damper was completed with the effect of the magnetic force acting between the dampers rings if the rotor journal takes an eccentric position. Application of the developed mathematical model made it possible to learn more on the vibration attenuation of rigid rotors supported by magnetorheological squeeze film dampers working in a wide range of operating speeds.

Frequency Dependent Spencer Modeling of Magnetorheological Damper Using Hybrid Optimization Approach

Abstract: Magnetorheological dampers have been widely used in civil and automotive industries. The nonlinear behavior of MR fluid makes MR damper modeling a challenging problem. In this paper, a frequency dependent MR damper model is proposed based on Spencer MR damper model. The parameters of the model are identified using an experimental data based hybrid optimization approach which is a combination of Genetic Algorithm and Sequential Quadratic Programming approach. The frequency in the proposed model is calculated using measured relative velocity and relative displacement between MR damper ends. Therefore, the MR damper model will be function of frequency. The mathematical model is validated using the experimental results which confirm the improvement in the accuracy of the model and consistency in the variation damping with the frequency.

Continuous hysteresis model using Duffing-like equation

Abstract: Many material and mechanical systems, such as magnetorheological (MR) dampers used for reducing vibration in engineering systems, have long-standing modeling and control problems because of their nonlinear hysteresis behavior. Existing hysteresis models, including discontinuous and piecewise-continuous functions, are nonideal for numerical computation, stability analysis, and control design. This study links the hysteresis characteristics of a Duffing-like equation and an input–output system through a very subtle observation. Thus, the hysteresis dynamics are approximated using a traceable, second-order nonlinear ordinary differential equation with an inertial element. In addition, the hysteresis stability associated with energy dissipation can be analyzed using the Lyapunov method in a more deterministic and systematic manner than has previously been possible. Experimental work and hysteresis identification of a realistic MR damper device are presented to illustrate the proposed Duffing-like modeling techniques.

Two-dimensional, integrated and semi-automatic controllable vibration damper in longitudinal and vertical directions

Abstract: The invention discloses a two-dimensional, integrated and semi-automatic controllable vibration damper in longitudinal and vertical directions. The two-dimensional, integrated and semi-automatic controllable vibration damper is characterized in that fixed supports are horizontally arranged along a longitudinal direction on a base; motion supports are located above the fixed supports; one parallelogram mechanisms in a vertical plane is formed in such a manner that the fixed supports and the motion supports are connected by means of a pair of parallelly-arranged rocking arm hinges; a rotary magnetorheological damper is fixed onto the base; a driven gear is fixed at a shaft end of the rotary magnetorheological damper; angular displacement of swinging of rocking arms is transferred to the rotary magnetorheological damper by means of a driving gear and a driven gear; an angular acceleration sensor is used for obtaining vibration state of the motion supports and feeding back to a controller of the rotary magnetorheological damper; and the controller is used for responding and controlling output damping force of the rotary magnetorheological damper in a real-time mode in order to achieve integrated control over two-dimensional vibration state in longitudinal and vertical directions.The two-dimensional, integrated and semi-automatic controllable vibration damper in longitudinal and vertical directions helps to simplify the two-dimensional vibration control system and effectively decrease cost of the system.

Magneto-rheological damper with multiple external round-hole damping channels

Abstract: The invention discloses a magnetorheological damper with multiple external round hole damping channels, and relates to the technical field of devices for adjusting damping characteristics by changing the viscosity of fluid. The damper comprises the multiple external round hole damping channels, a magnetorheological fluid cavity, an energy storage cavity, a piston assembly and electromagnetic coil assemblies. Compared with a conventional magnetorheological damper of a ring valve structure, according to the structure of the magnetorheological damper, because the multiple external round hole damping channels are evenly distributed outside the magnetorheological fluid cavity, the flow area of magnetorheological fluid is large, and the magnetorheological damper has the characteristic of being small in damping force under the zero-magnetic-field condition; meanwhile, because the multiple electromagnetic coil assemblies are arranged, the damping force can be increased under the action of a magnetic field. Thus, the magnetorheological damper has the advantage of being wide in damping force adjusting range.

Novel intelligent shock absorber integrating multilayer magnetorheological elastomers with magnetorheological damper

Abstract: The invention discloses a novel intelligent shock absorber integrating multilayer magnetorheological elastomers with a magnetorheological damper The shock absorber comprises the magnetorheological damper and a variable stiffness device comprising the multilayer annular magnetorheological elastomers and magnetorheological elastomer magnet exciting coil windings mounted between the multilayer annular magnetorheological elastomers respectively, wherein the magnetorheological damper comprises a cylinder barrel; the cylinder barrel is connected to the top end of the shock absorber through a spring; a piston plate is arranged in the cylinder barrel; a piston rod is fixedly connected to the lower side of the piston plate; the other end of the piston rod penetrates out of the cylinder barrel and is fixed at the bottom end of the shock absorber; a magnetorheological damper magnet exciting coil winding is wound on the side wall of the piston plate; the cylinder barrel is filled with a magnetorheological fluid; a damping device is connected with the variable stiffness device in parallel or in series Due to the integration of the multilayer magnetorheological elastomers and the magnetorheological damper, the stiffness and damping change range of the shock absorber is relatively large, a relatively good shock absorption effect can be achieved, and the shock absorber is compact in structure