Magnetorheological Valve Research Articles

Dynamic control simulation of a new joint model with energy recovery during walking, using magnetorheological fluids, for lower limb prosthesis

AbstractResearchers can now utilize new materials to create innovative models for lower limb prostheses and explore novel ways to use them for efficient dynamic control. To achieve user-friendliness, one area of research focuses on recovering and reusing kinetic walking energy for dynamic control. This paper proposes a new design for a magnetorheological (MR) valve, along with a rotary actuator which offers a dynamic control for a lower limb prosthesis. The design will allow the storage of the energy during heel and mid-foot contact phases and to utilize it during toe support to lift the foot off the ground and establish a balance for the lower limb prosthesis. The energy is transferred through a magnetorheological hydraulic circuit and stored using a pneumatic system. The speed of energy transfer is regulated by magnetorheological valves. A series of MR valve designs were proposed and evaluated experimentally, which allowed the identification of the most suitable variant in the targeted application context. The design of the lower limb prosthesis was simulated using SolidWorks, and its dynamic behavior was analyzed in ANSYS.

Novel Hydro-Pneumatic Interconnected Suspension Integrating Pipe-Connected Magnetorheological Valve Designed Based on Magnetic Gradient Pinch Mode—Experimental Study and Modelling

Novel Hydro-Pneumatic Interconnected Suspension Integrating Pipe-Connected Magnetorheological Valve Designed Based on Magnetic Gradient Pinch Mode—Experimental Study and Modelling

Experimental and numerical analysis of magnetorheological valve based on Herschel–Bulkley–Papanastasiou model

As a kind of smart material, magnetorheological (MR) fluids are widely used in various engineering applications. Choosing an appropriate rheological model to describe flow behavior is crucial in the design of MR actuators. In this paper, the Herschel-Bulkley-Papanastasiou (HBP) model was first developed to fit the rheological properties of the MR fluid. The coupling modeling of the flow field and magnetic field of the radial MR valve were established, and the distribution of the magnetic field, velocity field, shear stress, and shear rate of the radial MR valve were also analyzed. The rheological properties of MR fluids and the inlet and outlet pressures of the MR valve were experimental tests. The experimental and numerical results indicate that the HBP model can better fit the rheological characteristics of MR fluids than that of the BP model, and the numerical results can better predict the magnetic field and flow field characteristics of the MR valve.

Experimental study of hydraulic lifting platform based on multi-ring disc magnetorheological valve

To enhance the operational capabilities of a hydraulic lifting apparatus, a hydraulic lifting platform was engineered based on a multi-ring disc magnetorheological valve. The pressure drop characteristics of the multi-ring disc magnetorheological valve were determined through theoretical analysis, supplemented by magnetic field simulations to assess its performance. The effects of different currents on the stability and response time of the hydraulic lifting platform are studied, and the control accuracy of the hydraulic lifting platform position is verified. The results show that the saturation current of the magnetorheological valve is 2.5 A. The addition of current to the magnetorheological valve leads to a rapid increase in both actuator speed and acceleration, which then levels off. Similarly, the response time of the actuator decreases with an increasing current until it stabilizes. At a coil current of 1.5 A, the actuator achieves a speed of approximately 86 mm s−1, an acceleration of approximately 105 mm s−2, and a response time of approximately 7.15 s. Furthermore, the lifting position accuracy of the hydraulic lifting platform is ±1 mm.

Grasping the behavior of magnetorheological fluids in gradient pinch mode via microscopic imaging

Magnetorheological (MR) fluids are suspensions of micrometer-sized ferromagnetic particles in a carrier fluid, which react to magnetic fields. The fluids can be operated in several fundamental modes. Contrary to the other modes, the rheology and microstructure formation of the MR fluid in the gradient pinch mode have been studied to a far lesser extent. The magnetic field distribution in the flow channel is intentionally made non-uniform. It is hypothesized that the Venturi-like contraction is achieved via fluid property changes, leading to a unique behavior and the presence of a pseudo-orifice. The main goal is to investigate the presence of the Venturi-like contraction effect in the fluid by means of optical imaging and hydraulic measurements. To accomplish the goal, a unique test rig has been developed including a fluorescence microscope and MR valve prototype. The Venturi-like contraction hypothesis was confirmed. The results indicate that the effective flow channel size decreases by 92% at the maximum magnetic flux applied. This has a direct impact on the flow characteristics of the MR valve. The variation of the pressure–flow rate curve slope with magnetic field was demonstrated. The results provide valuable information for understanding the rheology and microstructure formation mechanism in MR fluids in the pinch mode.

Geometric optimization of magnetorheological damper for prosthetic ankles using artificial neural networks

In this work, the primary design constraints of a magnetorheological (MR) actuator and its stroke dimension have been found based on biomechanical requirements and anthropometric constraints of the ankle in a transtibial prosthesis. Based on the inverted slider-crank mechanism models, the force controller parameters of the MR damper are identified. Parameters of the MR dampers are evaluated through optimization that minimises the error between the prosthetic ankle moment and the desired ankle moment for normal level ground walking from experimental data. Furthermore, an artificial neural network (ANN) framework for the MR valve is developed where a three-layered ANN model has been utilised to forecast the magnetic flux density (MFD) across different regions of the MR valve. The data have been generated from an ANSYS-APDL software package using finite element magnetostatic analysis (FEMS). The ANN model outcomes match the FEMS results reasonably well. Finally, the ANN model is employed to find MFD and is used to optimize the MR valve. Optimal solutions are obtained that satisfy the goal function of maximising the damper force and minimising the energy consumption and weight of the MR damper. Subsequently, the optimized MR damper has been fabricated and tested experimentally and it has been found to produce enough force to act as an actuator in a prosthetic ankle.

Analysis of pressure drop and response characteristics of an enhanced radial magnetorheological valve based on magneto-fluidic coupling

To analyze the pressure drop characteristics of MR valves more realistically, a simulation method of coupling electromagnetic field and flow field was proposed in this paper. An enhanced radial MR valve with radial and annular compound paths was proposed, and its structure and working principle were also elaborated. Next, the mathematical equation of pressure drop was established using the non-Newtonian constitutive model of MR fluid Bingham-Papanastasiou. The dual physical model was completed by the sequential coupling way based on Maxwell equation and Naiver stokes equation. The distribution law of electromagnetic field and flow field in the process of mutual coupling was numerically simulated by COMSOL software. Furthermore, a series of pressure drop and response characteristics tests were performed for the proposed MR valve. Through the experimental analysis, it could be seen that the pressure drop and response time of the MR valve hardly change with the applied load and flow rate, while the pressure drop increases significantly and the dynamic response time basically decreases with the augment of the applied current. At an excitation current of 1.6 A, the maximum pressure drop of the experiment and simulation was 4.46 MPa and 4.84 MPa, respectively. Consequently, all the maximum relative errors were less than 7.9 %.

Assessment of the Dynamic Range of Magnetorheological Gradient Pinch-Mode Prototype Valves

Magnetorheological (MR) fluids have been known to react to magnetic fields of sufficient magnitudes. While in the presence of the field, the material develops a yield stress. The tunable property has made it attractive in, e.g., semi-active damper applications in the vibration control domain in particular. Within the context of a given application, MR fluids can be exploited in at least one of the fundamental operating modes (flow, shear, squeeze, or gradient pinch mode) of which the gradient pinch mode has been the least explored. Contrary to the other operating modes, the MR fluid volume in the flow channel is exposed to a non-uniform magnetic field in such a way that a Venturi-like contraction is developed in a flow channel solely by means of a solidified material in the regions near the walls rather than the mechanically driven changes in the channel’s geometry. The pinch-mode rheology of the material has made it a potential candidate for developing a new category of MR valves. By convention, a pinch-mode valve features a single flow channel with poles over which a non-uniform magnetic field is induced. In this study, the authors examine ways of extending the dynamic range of pinch-mode valves by employing a number of such arrangements (stages) in series. To accomplish this, the authors developed a prototype of a multi-stage (three-stage) valve, and then compared its performance against that of a single-stage valve across a wide range of hydraulic and magnetic stimuli. To summarize, improvements of the pinch-mode valve dynamic range are evident; however, at the same time, it is hampered by the presence of serial air gaps in the flow channel.

Performance analysis of the damper with built-in magnetorheological valve

Commercial vehicles are usually equipped with suspension seats to improve ride comfort. As a semi-active intelligent device, magnetorheological damper can effectively improve seat comfort when applied to seat suspension. Firstly, a novel damper with built-in magnetorheological valve (MRVD) based on the squeeze mode of magnetorheological fluid (MRF) is designed, which integrates the magnetorheological valve (MRV) into the piston. This structure adopts a bidirectional controllable flow channel, double coil, and double squeeze chamber. Secondly, the mathematical model of the MRVD is derived based on the Bingham plastic model of the MRF. Then, the distribution of magnetic flux density in the effective damping gaps is simulated using finite element method. Finally, it is shown from a comparative work between the simulation results from the derived mathematical model and experimental test results of the MRVD that the established mathematical model can predict the field-dependent damping force well. The idea of integrating the MRV into the piston provides a new approach for the application of magnetorheological technology.

Optimal Design of Magnetorheological Valve Using the Coupling of FE Magnetic Analysis and MOGA Optimization for Prosthetic Ankle

Optimal Design of Magnetorheological Valve Using the Coupling of FE Magnetic Analysis and MOGA Optimization for Prosthetic Ankle

Structural design and experimental study of multi-ring and multi-disc magnetorheological valve

In order to solve the problems of small pressure drop range and achieve lower response time and small power consumption of traditional control valves in automotive hydraulic lift, the magnetic circuit method was employed to design a new multi-ring and multi-disc magnetorheological valve based on magnetorheological fluid and its pressure drop mathematical model was established. Through the electromagnetic field simulation, the effect of current size, radial damping gap size, axial damping gap size and magnetic isolation thickness affect the performance of the multi-ring and multi-disc magnetorheological valve is studied. The pressure drop characteristics and response time of the multi-ring and multi-disc MR valve under different currents, different direction of loading current and different loads have been studied experimentally. The results show that the saturation pressure drop of the multi-ring and multi-disc MR valve is greater than 7 MPa, and the response time is 136 ms–178 ms, which proves the performance advantage of the multi-ring and multi-disc MR valve.

Highly Efficient Miniaturized Magnetorheological Valves Using Electropermanent Magnets

Fluidic systems enable actuation in various applications, such as automotive, medical, and industrial robotics. Miniaturized valves constitute a fundamental controlling element of modern fluidic systems, intriguing the interest of many researchers. This letter presents the design, implementation, and experimental validation of a miniaturized magnetorheological valve. The valve is highly efficient due to its capability of sustaining high loads with low energy consumption. This work includes the estimation strategy for the sustained load. Magnetorheological fluid is used both as an actuation fluid and as control medium. The inner iron core of the traditional magnetorheological valve is replaced with an AlNiCo-5 rod. The latter provides the possibility of magnetic energy storage, without continuous power supply. This changes the actuation mechanism from an electromagnet to an electropermanent magnet. The valve's capability to sustain pressure up to 1010 kPa, for a volume of 353 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> , is demonstrated experimentally. The fluid flow rate when the valve is open is 459 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> /s for a pressure difference of 993 kPa. The corresponding power consumption is negligible in steady-state condition, while consuming 15.3 mJ when activated and 6 mJ when deactivated. The experimental results also validate the possible tunability of the pressure sustaining capability of the valve.

Study on the structural design and performance of magnetorheological (MR) valve with hybrid supply magnetic source and double annular channels

Valve plays an important role in achieving precise position control for the hydraulic lift system. In order to improve the performance of hydraulic lift in precise motion, this paper proposes an MR valve with hybrid supply magnetic source and double annular channels. In addition, a structural model was established to perform pressure drop analysis. According to its working principle, it is proposed that this MR valve has two channels that work separately. There are three working modes in which the two channels work together, and the pressure drop of the MR valve can be calculated in different ways. Therefore, the MR valve with hybrid supply magnetic source and double annular channel performance test system is constructed, and the magnetic field inside the valve is simulated by performing magnetic field finite element analysis. Finally, a test bench of vehicle maintenance elevators is built to analyze whether the MR valve with hybrid supply magnetic source and double annular channels can achieve accurate control on the vehicle maintenance elevators. According to the experimental and simulation results, the pressure drop of the MR valve with hybrid supply magnetic source and double annular channels is affected by the current and channel operating mode, while the load makes little difference to the pressure drop. The worse the rising response time performance increases with increasing current, but the response time performance decreases without being affected by current. When a current greater than 1.5A is applied to the coil, the response time of the lifting platform is basically maintained at 6 s with the increase of current. The position accuracy is ±1 mm for the experimental platform of the vehicle maintenance lift table based on the MR valve with hybrid supply magnetic source and double annular channel hydraulic system.

Design and experimental characterization of a bypass magnetorheological damper featuring variable stiffness and damping

Magnetorheological (MR) fluid dampers (MRFDs) with variable stiffness and variable damping capability (VSVD-MRFDs) have demonstrated excellent vibration mitigation performance. However, there are limited studies on the development of bypass VSVD-MRFDs which offer both higher dynamic range and output force, apart from simple maintenance and straightforward assembly. In this study, a novel large-capacity VSVD-MRFD with an annular-radial bypass MR valve, as opposed to the typical practice of implementing the valve within the traveling piston in the hydraulic cylinder of the MRFD, is proposed. The main contribution of the present work includes: (a) providing the conceptional design and experimental dynamic characterization of the proposed VSVD-MRFD; (b) investigating the feasibility of the proposed damper for realizing the VSVD characteristics under wide ranges of loading conditions. A test rig was, thus, designed to perform experimental characterization of the proposed VSVD-MRFD under wide ranges of mechanical loading and magnetic field conditions. A qualitative analysis including force-displacement, and force-velocity characteristics, together with a quantitative analysis including dynamic range, equivalent viscous and stiffness coefficients, were conducted as a function of loading frequency, displacement amplitude, and applied current. Results showed a maximum dynamic range and maximum output force of 4.5 and 7.8 kN, respectively. Also, the maximum relative increase in the equivalent viscous and stiffness coefficients were obtained, respectively, as 425% and 488%, when the applied current is increased from zero to 2 A. The results confirm the potential of the proposed VSVD-MRFD for applications in off-road suspension systems. The externally designed bypass MR valve permits a straightforward design modification for realizing wide scalability of damping force in different applications (e.g., off-road vehicle suspension systems).

Design optimization and experimental evaluation of a large capacity magnetorheological damper with annular and radial fluid gaps.

This paper presents an optimal design of a large-capacity Magnetorheological (MR) damper suitable for off-road vehicle applications. The damper includes an MR fluid bypass valve with both annular and radial gaps to generate a large damping force and dynamic range. An analytical model of the proposed damper is formulated based on the Bingham plastic model of MR fluids. To establish a relationship between the applied current and magnetic flux density in the MR fluid active regions, an analytical magnetic circuit is formulated and further compared with a magnetic finite element model. The MR valve geometrical parameters are subsequently optimized to maximize the damper dynamic range under specific volume and magnetic field constraints. The optimized MR valve can theoretically generate off-state and on-state damping forces of 1.1 and 7.41 kN, respectively at 12.5 mm/s damper piston velocity. The proposed damper has been also designed to allow a large piston stroke of 180 mm. The proof-of-concept of the optimally designed MR damper was subsequently fabricated and experimentally characterized to investigate its performance and validate the models. The results show that the proposed MR damper is able to provide large damping forces with a high dynamic range under different excitation conditions.

Theoretical and experimental study on performance of compound-driven MR valve-controlled damper

A compound-driven magnetorheological (MR) valve is designed to cope with the low reliability and high energy consumption of traditional MR valves. The operating magnetic field of the valve is applied by both the excitation coil and ring magnet, maintaining excellent pressure drop performance even at zero current. To analyze the performance and obtain the variation law of the magnetic flux density and pressure drop, a pressure drop mathematical model and a magnetic field simulation model are established. The key parameters of the MR valve are also optimized using non-dominated sorting genetic algorithms-II. A dynamic performance test system is built, and the influence of the load on the pressure drop and hysteresis characteristics of the MR valve is studied. The results show that the optimized pressure drop and adjustable coefficient are improved by 4.7% and 8.6% respectively. The pressure drop grows nonlinearly with the electric current and reaches saturation at a current of 1.5 A, and a pressure drop of 1485 kPa is still generated at zero current. The output damping force of the compound-driven MR valve-controlled damper can be continuously adjustable, indicating that the dynamic performance of the damper can be controlled by adjusting the input current.

Energy-saving actuation signal for magnetorheological valve train by leveraging hysteresis effect

• Analysis of electromagnetic hysteresis effect in magnetorheological valve train. • Customized pulse actuation signal for leveraging the hysteresis effect in magnetorheological valve train. • Pulse signal optimization for energy saving operation of VVL that improves the engine efficiency. • Customized pulse signal saves actuation energy of magnetorheological valve train. Smart, adaptive, and effective magnetorheological (MR) technology-based devices are replacing conventional brakes, clutches, valves, and dampers. MR valve improves engine performance by enabling variable valve actuation. Constructing an MR valve train is simpler than other active valve systems. However, similar to other electromagnetic valves, the MR valve train consumes considerable electrical energy in controlling the resistance force of the MR fluid such that the valve can remain partially open or fully closed. Thus, an engine equipped with an MR valve expends additional fuel for the actuation of the valve system. In this study, instead of conventional direct current (DC) actuation, an energy-saving customized pulse (CP) signal is proposed for valve actuation by leveraging the electromagnetic hysteresis effect. The applied CP signal causes fluctuations in the generated magnetic flux, resistance force, and consequent valve position. Therefore, the variation in MR resistance force at various duty cycles and negative half cycles was investigated and compared with the required force to perform variable valve lift (VVL). Simulations indicated that a 35% duty cycle with 75% current during the negative half cycle was able to maintain the required force but results in negligible deviation in the resistance force which doesn’t affect the VVL operation. Therefore, the proposed method is advantageous over conventional DC input, conferring actuation energy-savings of approximately 28%.

Design and performance evaluation of a magnetorheological valve with mosquito-coil-plate fluid flow channels

This work proposed and fabricated a magnetorheological (MR) valve with mosquito-coil-plate fluid flow channels. By setting non-magnetic mosquito-coil-plate arc baffles in the radial fluid flow channels of the conventional radial MR valve, MR fluid was forced to flow circumferentially in the mosquito-coil-plate fluid flow channels surrounded by arc baffles. Thus, the effective fluid flow channels of the proposed MR valve were significantly lengthened in the case of fixed volume, and the radial resistance gaps could be easily adjusted by replacing valve cores with different thicknesses. In order to investigate the distributions of the magnetic flux lines and the changes of the magnetic flux density of the MR valve accurately, the 2D and 3D finite element models of the designed MR valve were established by using ANSYS software. Moreover, pressure drop and response time of the MR valve were experimentally evaluated, and the experimental results show that the designed MR valve can not only output larger pressure drop, but also achieve rapid response time. In addition, the proposed MR valve was used as control unit in a valve controlled cylinder system, and its damping performances were tested separately under different applied currents and harmonic excitations with different amplitudes and frequencies. The test results indicate that the proposed MR valve controlled cylinder system can output reliable damping forces in a variety of operating modes. • A new MR valve with mosquito-coil-plate fluid flow channels was designed. • The pressure drop performance was evaluated through theoretical analysis and experimental verification. • A MR valve controlled cylinder system was established, and its damping performance was investigated. • This proposed MR valve has significantly improved its performance by introducing mosquito-coil-plate fluid flow channels.

Development and experimental characterization of a large-capacity magnetorheological damper with annular-radial gap

Magnetorheological (MR) dampers with bypass arrangements and combined annular-radial fluid flow channels have shown superior performance compared to conventional MR dampers with single annular/radial fluid flow gaps. Achieving a higher controllable dynamic force range with low off-state but high on-state damping force is yet a significant challenge for developing MR dampers for high payload ground vehicle suspensions. This paper presents the conceptual design, fabrication, and experimental characterization of a mid-sized large-capacity MR damper equipped with a compact annular-radial MR fluid bypass valve. Extensive experimental tests were conducted to investigate the dynamic characteristics of the proposed MR damper considering wide ranges of excitation frequency, loading amplitude, and electrical current. The equivalent viscous damping and the dynamic range were calculated as functions of loading conditions considered. The proposed damper initially realized the maximum dynamic range and damping force of 2.3 and 5.54 kN, respectively. With MR valve design modifications, the maximum dynamic range and damping force were substantially increased, reaching 5.06 and 6.61 kN, respectively. The effectiveness of the proposed MR damper was subsequently identified by comparing its dynamic range with other conventional MR dampers in previous studies. The results confirmed the superior performance of the proposed MR damper and its potential application for highly adaptive suspension systems for off-road wheeled and tracked vehicles.

Multi-Physics Analysis of a Magnetorheological Valve Train with Experimental Validation

Magnetorheological (MR) fluid devices are widely used in active automotive control applications. However, MR fluid-based valve actuators are not in the limelight. This paper proposes a new flexible valve train with an MR fluid control system; the valve train can enhance the performance of internal combustion engines. A major component of this valve train is the magnetic plate block filled with MR fluid and surrounded by a magnetic coil. This plate block controls the magnetic field in this MR fluid and eventually facilitates flexible valve lifts and valve opening timings. This study overviewed the conceptual design, two-way coupled multi-physics numerical simulations, manufactured an MR valve prototype, and conducted experimental tests on a test bench to understand the real-time performance of the MR valve train. First, computer simulations were performed using a coupled magnetic and thermal multiphysics model to consider the Joule-heating effect of the magnetic coil in the MR magnetic plate block. The simulation results indicated that although the temperature of the MR fluid increased noticeably, it did not exceed the prescribed operating limits. The dimensions of the MR magnetic plate block were optimized. After computer simulations and optimization, a prototype of the proposed MR valve was fabricated and tested to understand its performance in real time. The experimental test results indicated the reliability of the proposed MR valve train in practical scenarios.