Magnetorheological Shock Absorber Research Articles

Vibration reduction and energy harvesting of the marine stern shaft-bearing systems with triboelectric generator

The stringent requirements for vibration reduction in marine propeller shaft are essential due to the increased effects of transverse vibration. In order to effectively minimize the energy consumption and realize the energy harvesting during the process of vibration control, a triboelectric generator is proposed for the marine stern bearing-shaft systems by a combination of vibration reduction and energy harvesting. The vibration reduction is achieved using an adjustable damping magnetorheological shock absorber. The energy harvesting is realized through contact electrification and electrostatic induction during the vertical contact-separation of electrode plate. The Poincaré surface of the shaft and bearing demonstrates that the proposed triboelectric generator can be applicable for the vibration reduction and energy harvesting. Meanwhile, the controlled responses of suspension travel, soleplate deflection, acceleration of shaft and bearing, and forces are subjected to analysis. The energy harvesting process encompasses the acquisition of resistor current, PDMS charge, open-circuit voltage and electrical energy of the system. Moreover, the influence of various model parameters on both vibration reduction rate and electrical energy harvesting are discussed. It is anticipated that a more optimal satisfaction in terms of vibration reduction and energy harvesting can be attained through the adjustment of model parameter.

Characteristics, application fields, and future development and challenges of shock absorbers

Vibrations potentially damage equipment and mechanical structures. To mitigate this potential harm, it is necessary to implement specialized vibration-damping equipment, engineering controls to minimize the transmission of vibrations, and the wearing of appropriate personal protective gear. These measures help safeguard the safety of both equipment and personnel while ensuring their normal operation and longevity. Nowadays, shock absorbers play a crucial role in various fields, mitigating external forces such as earthquakes and wind to protect equipment, structures, and individuals from the adverse effects of vibrations. This paper reviews the historical development of shock absorbers, spanning from the earliest friction dampers to the contemporary remotely controllable variants. This paper provides an overview of fundamental principles and diverse types of shock absorbers, including hydraulic shock absorbers, pneumatic shock absorbers, and magnetorheological shock absorbers. The applications of shock absorbers have been analyzed, emphasizing their significance in daily life. In addition, this paper underscores the future prospects of shock absorbers in environmental protection, sustainability, and their evolving role in safeguarding society.

Harmonic analysis of a marine shaft-bearing suspension system and its semi-active control with PID strategy

A stable operating state of the marine shaft-bearing system is essential to minimize the vibration level and improve the transmission efficiency of the ship power system. A semi-active control with PID strategy is proposed through an adjustable damping magnetorheological shock absorber and the combination of the electromagnetic actuator based on the existing suspension system. The harmonic response of the system is calculated through transfer function with various suspension stiffness and damping. The controlled behaviors include suspension travel, soleplate deflection, sprung shaft and unsprung bearing, are obtained through Matlab/Simulink. The proposed controller is demonstrated to be applicable through robustness analysis by comparing with passive and LQR control based on the disturbance of pulse width modulation. The controlled behaviors with minor stiffness and significant damping are noticed to be more satisfied through the influence comparison of suspension parameters. The controlled performance includes reduction rate, overshoot rate and setting time with various values of control factors are discussed to prove the suitability. The semi-active control for the transverse vibration of the marine shaft-bearing system is thus realized based on the adjustment of control parameters.

Experimental study on the nonlinear vibration of a new composite magnetorheological damping system

Magnetorheological shock absorbers provide poor damping force in shearing direction. Thus, a composite magnetorheological damper composed of a rubber spring and a magnetorheological damper is proposed to withstand shear loads. A new damper tester is designed to obtain the vibration signal of this damper under external excitation. The magnetorheological vibration-reduction system is a typical nonlinear system, which has higher requirements for information extraction. To obtain the deeper correlation between crucial parameters of the damper and its performance, the autoregressive higher-order spectrum model is established. The formulas of the autoregressive trispectrum and its two-dimensional slice spectrum, diagonal slice spectrum and one-dimensional slice spectrum are derived. Then, the characteristics of the trispectrum and its slices of a magnetorheological vibration-reduction system under different loading currents, working frequencies are discussed. The experiment results show that the composite damper has good performance compared with common rubber shock absorbers, and the higher-order spectrum and its slices exhibit different the distribution density of the spectral amplitude and the distribution of spectral peaks under different working states, which are closely related to the currents and frequencies. The higher-order spectra are effective to quantificationally describe nonlinear coupling, restrain gaussian noise and reserve phase components of the vibration system.

Analysis vehicle suspension based on magnetoreological shock absorbers

This article examines the issue of automotive suspensions. In particular, it is proposed to replace the classical scheme based on oil shock absorbers with a chassis using a magneto-rheological composition. The two technologies are compared with their pros and cons. Based on this, an assumption is made about the possibilities of using magneto-rheological shock absorbers today and what is the trend of their implementation. Keywords: suspension, shock absorber, magneto-rheological fluid, ride, comfort, safety, automobile, transportation, cargo transportation, passenger transportation, adaptive suspension control

Optimal control for soft-landing in elevator emergency crash using multiple magnetorheological shock absorbers

Protecting the occupants from surviving the casualties and severe injuries in elevator emergency crashes is always essential. This paper aims to explore the feasibility of using multiple magnetorheological shock absorbers (M-MRSAs) to attain the soft landing of a full-load elevator under impact velocities ranging up to 32 m/s. The resistance forces of MRSA with a bi-fold structure are predicted by evaluating the pressure drops using a nonlinear Bingham-plastic model considering the effects of minor loss. The optimal control for an M-MRSAs system achieving robustness concerning different mass loadings and impact velocities is investigated by formulating a multi-objective problem to minimize the induced peak acceleration with constrained time duration. The results demonstrate that the self-adapting MR yield force provides a smooth operation by minimizing the cycles of re-crash and rebound without incurring an end-stop impact. Furthermore, a plateau behavior of acceleration-displacement profiles is realized to effectively reduce the load transmission from overshoot accelerating force to the protected occupants and eliminate the injury risk.

One-way coupled numerical model utilizing Viscoelastic Maxwell model for MR damper

Describing the hysteresis behavior of magnetorheological (MR) shock absorber significantly facilitates the developers before manufacturing and control processes. However, most of the models developed to describe the phenomenon have been required experimental data of the manufactured absorber. In this study, the hysteresis behavior for a shock absorber has been characterized by developing a three-dimensional coupled numerical model that adapts Viscoelastic Maxwell Model to momentum equations of fluid flow. The viscosity of the MR fluid, which depends on the magnetic flux density, has been calculated with the Herschel-Bulkley model at each node of the fluid domain, coupled with the magnetic field analysis. The hysteresis relationship between force and velocity has been obtained from time-dependent CFD analyses on the deformed grid. It has been observed that the hysteresis behavior of the MR shock absorber has been attained with a good agreement when the data obtained from the developed numerical model are compared with the experimental data. In addition, besides estimating the hysteresis widths in the force-velocity curves, all effects and changes in time in the flow domain have been observed thanks to the model.

Hybrid vibration control using magnetorheological dampers and elastomers for civil structural

A hybrid vibration control system using magnetorheological (MR) shock absorbers composed of MR dampers and MR elastomers is proposed for structural vibration. A Bouc–Wen model is developed to describe the hysteresis of the MR shock absorbers. The experimental results validate that the proposed Bouc–Wen model can represent the dynamic behavior of the MR shock absorbers. Based on the proposed model, a force tracking control of the MR shock absorbers is developed. Finally, the hybrid vibration control system for a seven-story building, including the force tracking control and a fuzzy PD control, is proposed. Numerical simulation results verify the effectiveness of the proposed control method.

A New Design Model of an MR Shock Absorber for Aircraft Landing Gear Systems Considering Major and Minor Pressure Losses: Experimental Validation

This work presents a novel design model of a magnetorheological (MR) fluid-based shock absorber (MR shock absorber in short) that can be applied to an aircraft landing gear system. When an external force acts on an MR shock absorber, pressure loss occurs at the flow path while resisting the fluid flow. During the flow motion, two pressure losses occur: the major loss, which is proportional to the flow rate, and the minor loss, which is proportional to the square of the flow rate. In general, when an MR shock absorber is designed for low stroke velocity systems such as an automotive suspension system, the consideration of the major loss only for the design model is well satisfied by experimental results. However, when an MR shock absorber is applied to dynamic systems that require high stroke velocity, such as aircraft landing gear systems, the minor loss effect becomes significant to the pressure drop. In this work, a new design model for an MR shock absorber, considering both the major and minor pressure losses, is proposed. After formulating a mathematical design model, a prototype of an MR shock absorber is manufactured based on the design parameters of a lightweight aircraft landing gear system. After establishing a drop test for the MR shock absorber, the results of the pressure drop versus stroke/stroke velocity are investigated at different impact energies. It is shown from comparative evaluation that the proposed design model agrees with the experiment much better than the model that considers only the major pressure loss.

The rheological properties of multifunctional shear thickening materials and their application in vehicle shock absorbers

A composite with both shear thickening (ST) and magnetorheological (MR) properties is fabricated by composing carbonyl iron powder into an ST matrix. The rheological properties are studied and the relative ST effect of the samples prepared under vacuum and non-vacuum conditions are compared. Then, the hydraulic oil in a vehicle hydraulic shock absorber is replaced with ST gel and ST fluid. The compression and rebound forces of the shock absorber containing hydraulic oil and ST fluid are tested and compared. Equal amounts of multifunctional ST fluid (MSTF, self-made) and MR fluid (self-made) are poured into an MR shock absorber and the performances are compared against the commercial MR shock absorber. Finally, the comprehensive performance and forces are improved by replacing SiO2 with the silica powder due to the smaller mean particle size.

Performance Analysis of a Magnetorheological Shock Absorber Prototype Designed According to a Quasi-Static No-Slip Model

The aim of this paper is to investigate the limits of the quasi-static, no-slip approach when modeling the activation of magnetorheological (MR) devices. A quasi-static model is implemented to define the hydraulic and magnetic characteristics of an MR damper prototype. Then, an FE (Finite Element) magnetic simulation activity is carried out to validate theoretical findings, and an optimization procedure is carried out to adjust nominal geometry to actual application. Furthermore, a prototype is realized re-using the maximum number of components that constitute the existing conventional shock absorber. Finally, experimental tests at bench stands are performed. The predictable results demonstrate that neglecting the transient slipping effects, the Force–Velocity performance of the device is correlated with the model findings only for low current intensities acting in the magnetic circuit.

A novel passive adaptive magnetorheological energy absorber

For traditional magnetorheological (MR) shock absorbers, the damping force is proportional to the square of the impact velocity. The instantaneous peak value of the damping force can easily cause damage to the load structure or human body, which will reduce the buffering efficiency. The viscous damping force is significantly affected by the size of the gap. Therefore, by changing the flow gap under different buffer strokes by presetting, the damping force can be maintained at a constant output in the full piston stroke, thereby improving the buffer efficiency. That is, a large gap is used at high speed and a small gap is used at low speed. The increase of the magnetic damping force at a small gap is applied to compensate for the decrease of the viscous force at low speed. Only constant current needs to be applied during buffering, which can greatly reduce costs. Based on this idea, a novel MR damper based on axial variable damping gap (MRD-VDG) is proposed. The MRD-VDG design method for the constant value output of the damping force in the full piston stroke is discussed and applied. According to the different requirements of the damping force under different piston displacements, the damping gap of different axial position are preset to realize the constant value output of the damping force during the stroke. The damping force under different damping gaps is analytically derived according to the Bingham-plastic nonlinear flow model with minor losses. Combining with the finite element analysis to obtain magnetic fields at different damping gaps between piston and cylinder. To validate the performance of the proposed design method, the prototype of MRD-VDG is fabricated. Damping characteristic test and impact test are performed to measure the damping characteristics of the MRD-VDG under different excited conditions. The results show that the piston displacement history of the damping force in the experiment is agreed well with the displacement history of the desired F-S curve under the assumed speed. The buffer efficiency of the prototype under designed conditions (the ratio of the corrected theoretical constant damping force to the actual peak damping force) exceeds 90%. This demonstrates the effectiveness of the MRD-VDG design. This design method has significant application prospects under impact condition without complex control (such as gun buffer, landing buffer, etc.)

Research on the Damping Device with Adjustable Inertia and Damping

In this paper, a new type of composite structure is proposed based on the original semi-active suspension of magnetorheological shock absorber and automobile suspension with inertia container, and the structure is analysed theoretically. The proposed new composite device is composed of a hydraulic cylinder, a magnetorheological damper and a hydraulic motor. The magnetorheological damper is compounded in the hydraulic cylinder and connected to the hydraulic motor through a hydraulic pipeline. The magnetorheological damper has the function of adjusting the damping, and the hydraulic motor achieves the purpose of adjusting the inertia by changing the mass. In order to analyse the device, the mechanical characteristics of magnetorheological valve and hydraulic motor are modelled and analysed. A quarter-vehicle suspension simulation analysis was performed on the overall operating characteristics of the system. The analysis results showed that the compound device has good variable damping inertia capacity characteristics, which is of great significance for improving the semi-active control suspension system.

Automotive MR Shock Absorber Behaviour Considering Temperature Changes: Experimental Testing and Analysis

Abstract This study investigates the automotive magnetorheological (MR) shock absorber behaviour in conditions of changing temperature. Its temperature-dependent behaviour was quantified between ambient and maximal operating temperatures of the device. Aspects addressed include the temperature dependence of the control coil resistance in the absorber, the influence of operating current level on control coil temperature and the temperature dependence of the absorber force response and energy dissipation in the system. The results of experiments enabled us to evaluate the mechanical performance of the absorber at varied temperatures.

Experimental investigation of design parameters of temperature controlled semi-active shock absorber under different currents and velocities

The effectiveness of the design parameters that affect the performance of semi-active shock absorber with magnetorheological (MR) fluid varies with the current excitation and damping velocity. Temperature has a very important effect on the performance of MR shock absorbers. In this study, the design parameters of a temperature-controlled MR shock absorber are evaluated under different current excitations and velocities. The manufactured dampers are tested at different current excitations and velocities. The effective levels of the parameters are determined according to the damping force and dynamic range. The expected performances of the best designs for MR shock absorbers and the effect of each design parameter on the performance are statistically calculated according to the different currents and velocities. The results show that the damping force decreased by 24.6% with varying temperature. The effect of the gap width decreased by 48.33% and the effect of the active length and radius of the piston core increased by 24.71 and 25.97%, respectively, when the current excitation changed from 0.2 to 1.8 A. The effect of the gap width increased by 2.56%, while the active length decreased by 4.12% at different velocities.

Effect of variable magnetic field on the flow between two squeezing plates

In this paper, a viscous fluid is considered between two horizontal and infinite squeezing plates. The unsteady equations of mass and momentum conservation is coupled with the variable magnetic field and energy equations. The governing system of equations along with entropy generation is solved by the Parametric Continuation Method (PCM). A parametric investigation is plotted through graphs for the velocity field and magnetic field components. Also, the entropy generation due to heat transfer, magnetic field and fluid friction is studied through graphs and tables. It is derived that an increase in magnetic Reynolds number, squeezing number or Hartman number increases the fluid temperature. The magnetic field components are also increasing with increase in magnetic flux. It is also derived that an increase in the rate of momentum diffusion increases the entropy generation and Bejan number due to maximum disorderness of molecules near the plates. Applications of the study include automotive magneto-rheological shock absorbers, novel aircraft landing gear systems, heating-up or cooling processes, biological sensor systems and biological prosthetic etc.

Controllability of magnetorheological shock absorber: I. Insights, modeling and simulation**Part of work was done while Xian-Xu ‘Frank’ Bai was a joint PhD student of Chongqing University and University of Maryland, College Park.

The smart fluids—magnetorheological (MR) fluids show the potentials for high-speed shock mitigation applications because of their fast response and large controllable damping range. In order to match the high-speed applications of MR fluids, the structural design and controllability evaluation of MR actuators are of great significance. Controllability of MR actuators are defined to be evaluated by the mechanical behaviors (i.e. damping force controllability), including the controllable damping force range, dynamic range and constant stroking load velocity range, and response time performance (i.e. real-time controllability). We proposed an internal bypass MR shock absorber (MRSA) (Bai et al 2013a IEEE Trans. Mag. 49 3422–5), which presents the possibility in vibration control and shock mitigation applications. In the internal bypass MRSA, the gap formed by the coaxially assembled inner and outer cylinders is the flow channel for MR fluids. The electromagnetic coil windings evenly wound on the outer wall of the inner cylinder and the active rings contribute to the MR effect, and continuous adjustable damping is realized through applying current into the electromagnetic coil windings. In Part I of this paper, the principle and the mechanical behaviors of the internal bypass MRSA is further in-deeply investigated via theoretical modeling and simulations. Based on the fluid dynamics—parallel plate models and the finite element analysis software ANSYS/Fluent, the mathematical model and the fluidic entities of the internal bypass MRSA are established, respectively. Response time model of the internal bypass MRSA under a voltage driver is established. The static magnetic field distributions of the internal bypass MRSA under different current excitations are obtained via ANSYS/Workbench. The response times of the internal bypass MRSA under transient impulse current excitation and transient impulse voltage excitation are obtained by transient electromagnetic simulation. The damping force performance of the conventional unicoil MRSA with an electromagnetic coil winding in positon, multicoil MRSA with five electromagnetic coil windings in positon and the internal bypass MRSA are compared and analyzed. As compared with the conventional unicoil and multicoil MRSAs with coupled structures of the piston and the electromagnetic coil windings, the internal bypass MRSA with decoupled arrangement shows much better damping force controllability. Experimental test and controllability evaluation of the internal bypass MRSA will be conducted and presented in Part II of this paper.

Controllability of magnetorheological shock absorber: II. Testing and analysis

To specifically verify the application feasibility of the internal bypass magnetorheological shock absorber (MRSA) for high-speed shock mitigation systems, the controllability evaluation indexes of damping force controllability and real-time controllability of the developed internal bypass MRSA prototype are experimentally investigated in Part II of this paper. Using the self-developed drop-induced shock setup and servo-hydraulic testing machine at Hefei University of Technology, the damping force characteristics of the internal bypass MRSA, including the controllable damping force range, the dynamic range, and the constant stroking load velocity range, are tested under the high-speed impact and sinusoidal displacement excitations. The response time characteristics of the internal bypass MRSA prototype are tested under triangular displacement excitation on the servo-hydraulic testing machine, including the response times when the electromagnetic coil windings of the internal bypass MRSA energized by current driver and voltage driver. The controllability of the internal bypass MRSA for semi-active shock mitigation systems is further evaluated, analyzed, and discussed.

Applying of Transfer Effect and Information Entropy to Analyze the Magneto-Rheology Shock Absorber

Background . Known methods of enhancing the magneto-rheological damper operation characteristics are not enough structured to use them to calculate damping characteristics in wide temperature range, physical aspects of the transfer phenomenon are considered in the design task of the high-speed and accurate shock absorbers. Objective . The aim of the paper is to investigate transfer phenomenon and working processes of the magneto-rheological shock absorber. Methods . Experiments and calculation, based on experimental data, to describe heat and mass transfer (separately) processes including influence of the electromagnetic strength on them are carried out. Results . Processing of experimental data and calculation show that changing the electromagnetic power in range 0–26 W provides the flow regulation in range 0.25–0 ml/min. Dependence between the magnetic liquid flow rate and electromagnetic strength was established. The possibility of changing pressure difference between damper chambers by changing electrical current and voltage was proved. Conclusions. Taking into account the phenomenon of transport and physical effects makes it possible to learn the processes that occur in the magneto-rheological damper and magneto-rheological fluid more deeply. In-depth knowledge of phenomena and processes opens up new possibilities for taking into account operating modes in changing operating conditions. Despite the power consumption, the use of the magnetorheological effect is most suitable in the dampers of a small group (with a maximum resistance force of up to 600 N). The obtained law for a given fluid can be incorporated into the control algorithm for the operating characteristic of a magneto-rheological damper. The represented method provides possibility to take into account the transfer phenomenon and influence of ponderomotive force on damping characteristics of the magneto-rheology shock absorber.

Changes in the Resistance Force of a Magneto-Rheological Shock Absorber Induced by a Magnetic Field

In this study, we report the theoretical resistance force of a magneto-rheological (MR) shock absorber. We use the Bingham plastic model to theoretically represent the dynamic behavior of MR fluid flow in a circular pipe under the effect of a magnetic field. Because an MR fluid has yield stresses, the flow is divided into two regions: shear flow and plug flow. We reveal the relation between the resistance force of the MR shock absorber and the applied magnetic field. We conduct experiments and compare the experimental and analytical results to verify the theoretical approach.