Hybrid Magnetorheological Research Articles

Design, analysis and optimization of a hybrid fluid flow magnetorheological damper based on multiphysics coupling model

Magnetorheological (MR) dampers are widely used in industrial applications due to its simple structure, fast response and adjustable damping performance. However, the volume of the MR damper will be limited by the installation space, which hinders the application to some extent. In this paper, a hybrid fluid flow MR damper which can be used in antiseismic building is designed to achieve better damping performance under constrained volume size. The multiphysics coupling simulation model and circuit simulation model are also established. Numerical results show the output damping force is 6.367 kN, the dynamic adjustable range is 50.768, and the current input time is 31 ms under the applied current of 2.0 A. In order to improve the dynamic performance of the designed MR damper under constrained volume size, a multi-objective structural optimization method based on theoretical calculation model is proposed. Experiments are also conducted to investigate the dynamic performance of the initial and optimal MR damper. Compared with the initial MR damper, the output damping force and the dynamic adjustable range of the optimal damper are improved by 6.6 % and 46.3 %, while the energy consumption is reduced by 10.7 %, respectively.

High-performance magneto-rheological clutches for direct-drive actuation: Design and development.

This paper presents an improved design, complete analysis, and prototype development of high torque-to-mass ratio Magneto-Rheological (MR) clutches. The proposed MR clutches are intended as the main actuation mechanism of a robotic manipulator with five degrees of freedom. Multiple steps to increase the toque-to-mass ratio of the clutch are evaluated and implemented in one design. First, we focus on the Hall sensors’ configuration. Our proposed MR clutches feature embedded Hall sensors for the indirect torque measurement. A new arrangement of the sensors with no effect on the magnetic reluctance of the clutch is presented. Second, we improve the magnetization of the MR clutch. We utilize a new hybrid design that features a combination of an electromagnetic coil and a permanent magnet for improved torque-to-mass ratio. Third, the gap size reduction in the hybrid MR clutch is introduced and the effect of such reduction on maximum torque and the dynamic range of MR clutch is investigated. Finally, the design for a pair of MR clutches with a shared magnetic core for antagonistic actuation of the robot joint is presented and experimentally validated. The details of each approach are discussed and the results of the finite element analysis are used to highlight the required engineering steps and to demonstrate the improvements achieved. Using the proposed design, several prototypes of the MR clutch with various torque capacities ranging from 15 to 200 N·m are developed, assembled, and tested. The experimental results demonstrate the performance of the proposed design and validate the accuracy of the analysis used for the development.

Personalized Gait Treatment Using Passive Controllable Ankle Foot Orthosis

Ankle Foot Orthosis (AFO) is usually prescribed for gait treatment. Low cost, easy to fabricate, safe, long term usage, and personalized AFO is demanded to facilitate and accelerate the prescription process, which is iterative, individualized, and collaborative. Passive Controllable AFO (PICAFO) was developed to fulfil the demand, consisting of several research works, such as the gait detection method, smart actuator design, and controller development. Two gait detection methods had been considered. Firstly, the system utilized the Electromyography (EMG) biosignal to detect the stance and swing phase. Secondly, hybrid Magnetorheological Elastomer (MRE) is used to detect four gait phases based on foot contact. The smart actuator, a small scale Magnetorheological (MR) brake, had been constructed, which generated 2.1 Nm maximum damping stiffness to partially support the ankle stiffness. The controller is essential because controlling the damping stiffness accordingly to the current gait ensures positive assistance. The latest version of the PICAFO controller utilized ankle velocity reference to control the MR brake stiffness, which can be estimated based on the user’s walking speed and body mass index. The presented research works show that achieving personalized gait treatment using the PICAFO system is possible.

Design and geometric parameter optimization of hybrid magnetorheological fluid damper

A hybrid type magneto-rheological (MR) fluid damper based on electromagnet and two permanent magnets apart from electromagnet was designed and its characteristics were analyzed numerically. In the proposed MR damper, the magnetic field is generated by the permanent magnet and raised by the additional electromagnet. This combination provides a larger amount of damping force with lower consumption of electric energy. The proposed model has an additional advantage of providing a moderate damping force in case of electromagnet failure. The magnetic circuit of a hybrid MR valve was analyzed by applying Kirchhoff’s law and magnetic flux conservation rule. A 2D axisymmetric model of the proposed hybrid MR damper was developed in commercial software where magnetic field properties are analyzed by finite element method. The optimization process was developed to optimize the geometric parameters and generated damping force using design of experiment (DoE) technique. The damping force of the MR damper was selected as an objective function. The optimal solution to the optimization problem of the hybrid MR valve structure was evaluated and compared with the solution obtained from the initial parameters. It is demonstrated that the novel hybrid type provides higher damping force than the previous model.

A Lightweight Magnetorheological Actuator Using Hybrid Magnetization

This article presents the design and validation of a lightweight magnetorheological (MR) clutch, called hybrid magnetorheological (HMR) clutch. The clutch utilizes a hybrid magnetization using an electromagnetic coil and a permanent magnet. The electromagnetic coil can adjust the magnetic field generated by the permanent magnet to a desired value and fully control the transmitted torque. To achieve the maximum torque-to-mass ratio, the design of the HMR clutch is formulated as a multiobjective optimization problem with three design objectives, namely the transmitted torque, the mass of the clutch, and the magnetic field strength within the clutch pack. A prototype of the HMR clutch is fabricated, and its dynamic performance is experimentally validated. Experimental results clearly demonstrate the advantages of the HMR clutch in applications requiring fast and precise motion and torque control.

Soft hybrid magnetorheological elastomer: Gap bridging between MR fluid and MR elastomer

Two major branches of the magnetorheological (MR) materials are MR fluids and MR elastomers. The MR fluids largely suffer from the sedimentation problem. On the other hand, MR elastomers conquer the sedimentation problem but have a lower MR effect. A magnetic field is required when an anisotropic configuration of the magnetic particles in the MR elastomer is desired. In this paper, we present a gap bridging material between MR fluids and MR elastomers, which may overcome the sedimentation problem of MR fluid as well as exhibits the anisotropic MR effect but avoids the need of a magnetic field during the crosslinking process as required for the fabrication of conventional anisotropic MR elastomer. A soft hybrid MR elastomer has been developed by forming a core-shell structure. The core consists of a mixture of magnetic particles and a carrier medium. Two types of carrier media have been adopted, named as fluid core and solid core. The shell is made from an elastomer. The investigation was performed to understand the effect of the concentration of magnetic particles in both liquid and solids cores as well as the effect of viscosity of the carrier fluid in the liquid core. The magnetorheological study revealed that the high viscosity carrier fluid is not as good as a low viscosity carrier fluid for the shear stress enhancement. However, for the core-shell soft hybrid MR elastomers, MR effect exhibited by the high viscosity carrier fluid core (>1000 Pa.s) was found to be as good as the low viscosity carrier fluid core. The high viscosity carrier fluid also overcomes the sedimentation problem of MR fluids and also exhibits a remarkable MR effect even in a moderately strong magnetic field. Similarly, it also exhibits the anisotropic MR effect when the direction of the applied magnetic field is changed, however, no magnetic field was applied during the crosslinking as typically required for conventional anisotropic MR elastomers. Such core-shell soft hybrid MR elastomers with high viscosity fluid core potentially bridge the gap between MR fluids and MR elastomers and open a new door of MR materials’ applications that might have not been achieved by the exclusive utilization of the previous MR materials.

Magneto-elastic properties of isotropic MR elastomers with a tri-modal particle size distribution

Magnetorheological (MR) elastomers, which undergo a change in their shape, physical and mechanical properties as a response to external magnetic fields, belongs to the family of filled elastomer. In order to determine whether different particle size combinations might influence the composite's behavior, a series of complicated multiphase materials that have stable performance are successfully prepared in the present study. The related magneto-mechanical coupling behavior of the MR elastomers is evaluated experimentally and theoretically. The results demonstrate that the particle size distribution had an important influence on the mechanical properties of the hybrid MR elastomers. In addition, there was an optimal mixture ratio for the large, medium, and small particles. By applying a modified constitutive relationship of hyperelasticity, the cycle deformation behaviors of the MR elastomers under a magnetic field environment are subsequently explained. Many of the qualitative theoretical results were in good agreement with experimental observations. This study provides a convenient approach for the investigation of the mechanical properties and behavior of such soft magnetic composites for use in engineering applications.

Patterned Magnetorheological Elastomer Developed by 3D Printing

This article delineates the characterization of the 3D printed MR elastomer through a forced vibration technique in the squeeze mode of operation. An anisotropic hybrid magnetorheological (MR) elastomer is developed via 3D printing. The 3D printed MR elastomer consists of three different materials; magnetic particles, magnetic particles carrier fluid, and an elastomer. MR fluid filaments are encapsulated layer-by-layer within the elastomer matrix using a 3D printer. When a moderately strong magnetic field is applied, the 3D printed MR elastomer changes its elastic and damping properties. The hybrid 3D printed MR elastomer also shows an anisotropic behavior when the direction of the magnetic field is changed with respect to the orientation of the printed filaments. The relative MR effect is higher when the applied magnetic field is parallel to the orientation of the printed filaments. The maximum change in the stiffness is observed to be 65.2% when a magnetic field of 500 mT is applied to the MR elastomer system. This result shows that the new method, 3D printing could produce anisotropic hybrid MR elastomers or possibly other types.

Hybrid Magnetorheological Elastomer, the Future of Gait Detection

This article aims to present a brief review on sensors used for gait detection in Ankle Foot Orthosis (AFO) application. Both the advantages and disadvantages of sensors such as EMG sensor, rotary encoder, foot switches, and force plate are highlighted in this article. Authors also addressed the four characteristics of sensors for gait detection; uniformity, installation, flexibility, and multi-measurement. In addition, the sensors were then compared based on the characteristics. The foot switch was identified as the most compatible sensor for gait detection. However, the sensor was also discovered to contain problems in its durability and uneven grounding. Consequently, the authors propose an introduction to a new material, hybrid Magnetorheological Elastomer (MRE). Coincidentally, the mentioned material possesses attributes of thin dimensions with adjustable stiffness. The thin dimension allows the hybrid MRE to be placed under the AFO sole. Furthermore, with an accurate degree of stiffness, the hybrid MRE allows for adjustment leading to a higher level of durability of the sensors which remains fine even if stomped on the user. In conclusion, the authors propose a further study on hybrid MRE AFO for the next study.

Development of hybrid magnetorheological elastomers by 3D printing

Intelligent or smart materials have one or more properties that can be significantly changed in a controlled fashion by external stimuli, such as temperature, pH, electric or magnetic fields, etc. Magnetorheological (MR) materials are a class of smart materials whose properties can be varied by applying an external magnetic field. In this work, the possibility of employing a suitable 3D printing technology for the development of one of the smart MR materials, the magnetorheological elastomer (MRE) has been explored. In order to achieve such 3D printing, a multi-material printing is implemented, where a controlled volume of MR fluid is encapsulated within an elastomer matrix in the layer-by-layer fashion. The choice of printing materials determines the final structure of the 3D printed hybrid MR elastomer. Printing with a vulcanizing MR suspension produces the solid MR structure inside the elastomer matrix while printing with a non-vulcanizing MR suspension (MR fluid) results in the structures that the MR fluid is encapsulated inside the elastomer matrix. The 3D printability of different materials has been studied by measuring their rheological properties and we found that the highly shear thinning and thixotropic properties are important for 3D printability. The quality of the printed filaments strongly depends on the key printing parameters such as extrusion pressure, initial height and feed rate. The experimental results from the forced vibration testing show that the 3D printed MR elastomers could change their elastic and damping properties when exposed to the external magnetic field. Furthermore, the 3D printed MR elastomer also exhibits the anisotropic behavior when the direction of the magnetic field is changed with respect to the orientation of the printed filaments. This study has demonstrated that the 3D printing is viable for fabrication of hybrid MR elastomers with controlled structures of magnetic particles or MR fluids.

Optimization and Testing of a New Prototype Hybrid MR Brake With Arc Form Surface as a Prosthetic Knee

In this present research work, a new configuration of the hybrid magnetorheological (MR) brake via T-shaped drum with an arc form surface boundary—the biomechanical geometric design of the hybrid MR brake as a prosthetic knee—is discussed and experimentally tested. The main purpose of this study is to develop a prosthetic knee with one rotary disc to fulfill the desired objective. To achieve this, three steps are considered. In the first step, to model the brake, slab method modeling is used to calculate the braking torque due to the arc surface. In the second step, the biomechanical geometric design is adjusted as an optimization problem to maximize the braking torque, minimize the instantaneous electrical power dissipation and maximize torque density via three biomechanical constraints. In the third step, the proposed prosthetic knee is verified through simulation and experiment. Two evaluation criteria namely, controllability and efficiency are considered for the fabricated MR brakes. The results demonstrate that the optimized MR brake with 0.69-kg weight generates 38.5-N·m braking torque with more reactivity.

Performance of Semi-Active Base Isolation Systems under External Explosion

Structures designed against earthquake loads based on using control systems may experience explosions during their lifetime. In this paper, the performance of a hybrid control system composed of a low-damping base isolation and a supplemental magneto-rheological (MR) damper under external explosion has been studied. Base isolation system has the ability of decreasing the maximum structural response under blast loadings by shifting the period of the structure. In addition, MR damper improves the base isolation system performance by controlling the base drift of the structure. Hence, in this paper, the capability of a hybrid base isolation system equipped with an MR damper at the base has been evaluated in reducing the maximum structural response and base drift under external blast loadings. To determine the voltage of the semi-active MR damper, the H2/Linear Quadratic Gaussian (LQG) and clipped-optimal control algorithms have been applied. For numerical simulations, a 10-storey shear frame subjected to blast loadings applied on different floors has been considered and the performance of the hybrid isolation system and MR damper has been studied. The results have proven the effectiveness of the hybrid control system in controlling the maximum response and base drift of the isolated structure against spherical external explosion. Furthermore, comparing the performance of the hybrid passive and semi-active base isolation systems indicates that the semi-active hybrid base isolation system is more effective in reducing the root-mean-square (RMS) value of the base drift. Similarly, it has been found that the semi-active hybrid base isolation system also performs better than the high-damping base isolation system.

Hybrid Magnetorheological Elastomers: Effects of the magnetic field on some electrical properties

Abstract Hybrid magnetorheological elastomers (HMREs) were manufactured from sponges filled with magnetorheological suspensions (MRSs) made of silicone oil (SO) and carbonyl iron in 10%, 30% and 60% volume fractions (Φ). The HMREs were obtained from polymerisation of a solution containing silicone rubber (SR), catalyst and MRSs. Flat capacitors (FCs) were manufactured using HMREs as dielectrics, and Cu-reinforced planar structures with graphene nanoparticles (nGr) embeded as electrodes, and the electric resistance (R) and capacity (C) of these FCs were measured as a function of the gradient (δ) of the applied magnetic field. Based on the as-determined C(δ)Φ and R = R(δ)Φ dependences, it is shown that both the dielectric and elastic behavior of the HMREs are influenced by the applied magnetic field and to an extent that depends on the volume fraction Φ. The obtained results are presented and discussed in terms of the dipolar approximation, by assuming the HMRE as a linear elastic body.

Optimal design of a novel hybrid MR brake for motorcycles considering axial and radial magnetic flux

This work presents an optimal solution of a new type of motorcycle brake featuring different smart magnetorheological (MR) fluids. In this study, typical types of commercial MR fluid are considered there for the design of a motorcycle MR brake; MRF-122-2ED (low yield stress), MRF-132-DG (medium yield stress) and MRF-140-CG (high yield stress). As a first step, a new configuration featuring a T-shaped drum MR brake is introduced and a hybrid concept of magnetic circuit (using both axial and radial magnetic flux) to generate braking force is analyzed based on the finite element method. An optimal design of the MR brake considering the required braking torque, the temperature due to friction of the MR fluid, the mass of the brake system and all significant geometric dimensions is then performed. For the optimization, the finite element analysis (FEA) is used to achieve principal geometric dimensions of the MR brake. In addition, the size, mass and power consumption of three different MR motorcycle brakes are quantitatively analyzed and compared.

High-Performance Hybrid Magnetorheological Materials: Preparation and Mechanical Properties

To improve mechanical performance of magnetorheological elastomers (MREs), two novel hybrid magnetorheological elastomers that were embedded with magnetorheological fluids (MRFs) and magnetorheological gels (MRGs) were fabricated. In this work, MRFs and MRGs were injected into different numbers of holes that were punched on MRE specimens regularly. The nonlinear mechanical properties of the as-prepared magnetorheological fluid-elastomers (MRFEs) and magnetorheological gel-elastomers (MRGEs) were investigated in the presence of external homogeneous magnetic fields. The modulus, loss factor, and hysteresis were evaluated with a modified dynamic mechanical analyzer (DMA) and vibrating sample magnetometer (VSM). Dependence of the rheological response on the volume fraction was also investigated. As the experimental results show, not only were the initial moduli of the two novel hybrid magnetorheological materials higher than those of both the MRFs and MRGs, but also their magnetorheological (MR) effects were better than those of MREs. The loss factors of the two new hybrids were different from those of traditional MREs. Moreover, their dynamic properties changed according to the different volume ratios of MRFs and MRGs injected into the MRE specimens. These results suggest that the two novel hybrid magnetorheological elastomers are improved systems with volume-fraction-dependent rheological responses and the mechanical properties of MREs can be improved by embedding them with MRFs and MRGs.

2520 MRダンパによる連結構造物の振動制御(J10-5 振動・音響抑制,J10 知的材料・構造システム)

In this paper we propose a semi-active vibration control method for multiple high-rise buildings arranged in parallel. Using this method, it is possible to control vibrations of high-rise buildings against strong winds and large earthquakes. In this study, two model buildings are connected with hybrid MR (Magneto-Rheological) dampers. The objective of this research is to control the first and second bending modes of each building using this method. The control effect is evaluated by exciting the base of the structures by time response and measuring the frequency response of the structures. Simulation results show that fairly good control performance has been achieved by this method.