Magnetorheological Research Articles

Design and actuation of a state transformable amorphous soft robot

Traditional solid-state magnetic robots have limited deformability due to their fixed structures, while liquid robots sacrifice stiffness and stability for deformability. To overcome these limitations, a novel state transformable amorphous soft robot, referred to as the AMS-Robot, has been developed utilizing magnetorheological fluid (MRF). This robot can swiftly transition from a Newtonian fluid state (in a weak magnetic field) to a solid Bingham plastic state (in a strong magnetic field) in response to varying magnetic fields. The locomotion of our AMS-Robot, steered by a gradient magnetic field acting on magnetic droplets, converts magnetic energy into kinetic energy and viscous dissipation, enabling functions like deformation, navigation, split-merger, and gradient crawling. Remarkably, the robot exhibits the ability to transport objects weighing approximately 150 times its own weight under a strong magnetic field. Through simulations of its movement within blood vessels, the potential of the AMS-Robot in medical applications is highlighted, showcasing its proficiency in tasks like precision drug delivery and thrombus removal. This groundbreaking approach holds significant promise for advancements in the field of medical applications.

Experimental and theoretical investigation on magnetorheological elastomers containing carbonyl iron particles coated with silane coupling agent

Magnetorheological (MR) elastomer composites, comprising soft silicone rubber, various additives, and different weight fractions of carbonyl iron particles (CIPs) coated with silane coupling agent, are produced via a novel manufacturing process in an anisotropic state. This study encompasses both experimental and modeling investigations into the dynamic viscoelastic properties of magnetorheological elastomer (MREs) in shear mode under varying magnetic fields, displacement amplitudes, and frequencies. Two MRE vibration mitigation devices are fabricated to experimentally assess the shear storage modulus and the loss factor of MREs. The experimental findings reveal a pronounced MR effect in the MRE devices, where both the shear storage modulus and the loss factor increase with rising magnetic fields, frequencies, and particle weight fractions, yet decrease with higher displacement amplitudes. A modified fractional-derivative equivalent parametric model, grounded in a magnetic field- and frequency-dependent shear modulus model along with internal variable theory, is proposed to describe the effects of these key influencing factors on the MREs’ dynamic viscoelastic properties. Comparative analysis of experimental and numerical data demonstrates that this refined mathematical model can accurately represent the dynamic viscoelastic properties of MREs.

Fabrication and property research of a new 3D-Printable magnetorheological elastomer (MRE)

In order to meet the growing design demands for shape and structure of magnetic functional materials, particularly Magnetorheological Elastomers (MREs), additive manufacturing technology has been introduced into MRE production. Reported works of printable MRE (p-MRE) have successfully obtained high relative magnetorheological (MR) performance comparable to traditional MRE. However, there are still few studies on p-MRE with both high relative and absolute MR effects that is required for some applications such as intelligent dampers in automotive industry. In this study, polyurethane (TPU) and carbonyl iron powder (CIP) were utilized as raw materials to formulate p-MRE with high printability and high comprehensive MR performance. Based on the fused deposition modeling (FDM) process, a printing strategy suitable for this p-MRE material was determined through experimental design (DOE). The test result showed that the comprehensive MR performance of the p-MRE sheet samples obtained through linear printing path exceeded the majority of previously reported p-MRE materials. In addition, based on the analysis of the correlation between magnetic hysteresis like effect and MR effects, a circular printing path that may be beneficial for improving MR performance was proposed and corresponding p-MRE sheet sample was printed. The test results showed that compared with the linear printing path, the circular printing path further increases the comprehensive MR effect of the sheet sample to a maximum absolute MR effect of 4.2 MPa and a maximum relative MR effect of 620 %, which is comparable to most conventional MRE materials. Additionally, a theoretical framework associating magnetic field strength and filling density was proposed to explain peculiar phenomena observed in the experiments. On the basis of previous research on MREs and filler modified elastomers, a hypothesis was proposed to link magnetic field intensity with filler density, allowing the existing theory of filler modified elastomers to be used to explain the special phenomena observed in our experiments.

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.

A Review on Structural Configurations of Magnetorheological Clutch

Abstract:: In recent years, with the development of "smart materials", magnetorheological fluids have been widely used in the fields of mechanical transmission, aerospace, construction, and medical treatment because of the unique rheological properties that can occur under the action of an applied magnetic field. Magnetorheological clutches with magnetorheological fluid as the working medium have the advantages of simple structure, low noise, fast response, and easy control compared with traditional clutches. In order to provide an overview of the issues encountered by magnetorheological clutches in their current applications and to summarize the optimization designs implemented to address these issues, with the aim of promoting the widespread application of magnetorheological clutches. The basic theory of magnetorheological fluid and magnetorheological clutch design method is introduced. The related patents of magnetorheological clutch structure design are reviewed. The characteristics and advantages of magnetorheological clutch in different working modes are summarized. This study introduces the basic theory of magnetorheological fluid. The problems existing in the application of magnetorheological clutch are explained. The characteristics of magnetorheological clutch based on shear mode, shear-extrusion mode and heat dissipation mode are described. The development trend of magnetorheological clutch is discussed. This paper provides an important basis for the design and application of magnetorheological clutch, offers specific guidance for improving the torque transmission capacity and heat dissipation capacity of magnetorheological clutch, and lays a theoretical foundation for the wide application of magnetorheological clutch in the future.

Investigations of Sustainable Biodegradable Oil and Magnetic Particle‐Based Magnetorheological Fluid Dampers for Vibration Attenuation of a Rotor Dynamic System

This article aims to study the physical characterization and performance of a material‐based magnetorheological fluid (MRF) dampers for vibration attenuation of a high‐speed rotor–motor system near resonance. Four samples are synthesized by combining electrolytic iron and carbonyl iron (CI) with Castor and Karanja oil and experimentally investigated for their contribution to vibration attenuation. The results demonstrate effective vibration attenuation of the biodegradable oil‐based MRF damper than the nonbiodegradable oil‐based MRF damper. The best vibration attenuation is observed in the case of moderately viscous MRF. CI‐based samples exhibit a lower sedimentation rate, hence recommended for MRF. The vibration amplitude is maximum for the Castor oil‐based MRF damper, however, is minimum for the Karanja oil‐based MRF damper. The steady and transient results of vibration amplitudes are obtained and analyzed for different currents supplied to the MRF damper. The range of unstable speed near resonance is also obtained. The prepared samples show higher attenuation of 6–25% than Sample 5. The vibration amplitude attenuation of Sample 4 and Sample 5 are 47% and 22%, respectively. The findings of this study carry significant implications for controlling the vibration of the dynamic system using an eco‐friendly damping system.

Effect of the surface coating of carbonyl iron particles on the dispersion stability of magnetorheological fluid

The dispersion stability of carbonyl iron particle (CIP)-based magnetorheological fluid (MRF) is improved by CIP, which particle is etched with hydrochloric acid (HCl) to form porous structure with many hydroxyl groups and subsequently coated with silane coupling agents that have varying chain lengths. The microstructures, coating effect and magnetism of the CIPs were examined using the Scanning Electron Microscopy, Automatic Surface and Porosity Analyzer (BET), Fourier-Transform Infrared Spectroscopy, Thermogravimetric Analysis and Vibrating Sample Magnetometer. Furthermore, the rheological properties and dispersion stability of the MRFs were assessed using a Rotating Rheometer and Turbiscan-lab. The results revealed that the nanoporous structure appeared on the CIPs and the specific surface area increased remarkably after being etched by hydrochloric acid. Additionally, as the chain length of the silane coupling agent increases, the coated mass on the particles increases, the the density and the saturation magnetization of particles decreased, and the coated particles with different shell thicknesses were obtained; without a magnetic field, the viscosity of MRF prepared by coated particles increase slightly, due to the enhancement of special three-dimensional network structure; under a magnetic field, the viscosity of the MRF decreased distinctly; the sedimentation rate of MRF decreased from 58 to 3.5% after 100 days of sedimentation, and the migration distances of the MRFs were 22.4, 3.7, 2.4, and 0 mm, with particle sedimentation rates of 0.149, 0.019, 0.017, and 0 mm/h, respectively. The MRF with high dispersion stability was obtained, and the etching of CIP by HCl and the proper chain length of the coating of silane coupling agent were proved effective manners to improve the dispersion stability of MRF.

Additive effect of poly(N-methylaniline) coated Fe3O4 composite particles on carbonyl iron based magnetorheological fluid

Poly(N-methylaniline) (PNMA) coated magnetite (Fe3O4) (PNMA@Fe3O4) composite particles synthesized through both chemical oxidative polymerization and chemical co-precipitation processes were used as a magnetic additive for carbonyl iron (CI)-based magnetorheological (MR) fluid. The effect of the additive’s content on the rheological characteristics of the MR fluid in the presence of an externally applied magnetic field was studied along with its effect on the sedimentation ratio compared with that of CI-based MR fluid. Shear stress curves as a function of the shear rate of the CI-based MR fluids with the additive were found to be well-fitted by the Herschel–Bulkley equation and the slope of the dynamic yield stress was determined to be 2.0. The curves also showed yield stresses higher than those of the CI-based MR fluid for different magnetic field strengths. Specifically, the CI-based MR fluid with 1.0 wt% additive showed the highest yield stress and the best solid-like properties among the tested samples. Furthermore, the sedimentation issue for the CI-based MR fluid was found to improve significantly, especially for the lowest settling rate of the MR fluid with 1.0 wt% additive. The addition of 1.0 wt% PNMA@Fe3O4 additive resulted in the CI-based MR fluid exhibiting the best properties, owing to improved rheological features and a reduced sedimentation rate.

Dynamic Characteristics of Magnetorheological Mounted Metal Rubber Structures Under Multi-physics Coupling Conditions

To accurately predict the dynamic characteristics of MR mounting, the nonlinear electromagnetic coupling law between MR liquid and soft magnetic material and the solid-liquid interaction, the electromagnetic coupling and fluid-structure coupling mathematical models and numerical simulation models of MR mounting are established. Through the magnetorheological mounting test, the simulation results are compared with the experimental results, and the validity of the numerical simulation model is verified. On this basis, the distribution effect of electromagnetic coupling in a magnetic circuit is analyzed. According to the Bingham model, the variation rule of magnetorheological fluid damping force was deduced. The magnetic field simulation results are introduced into the fluid model and the fluid-solid model, and the fluid-solid coupling effect of the numerical model of magnetorheological mounting is calculated. The dynamic and static characteristics of magnetorheological mounting under different current excitation conditions are simulated. It provides the basis for designing and simulating multi-physical field simulation of MR mounting.

Microscopic modeling and experimental investigation of inner surface magnetorheological polishing based on particle micromechanics

Traditional surface polishing methods are no longer able to meet the ultra-precision requirements of the high-tech industry for the inner surface of the pipe, but magnetorheological polishing technology is very suitable due to its advantages of high precision, fast controllability and good deposition stability. However, there is even less investigation on the microforce analysis, chaining mechanism and micromodeling methods of magnetorheological polishing fluid (MRPF), and the polishing mechanism of MRPF has not been explored yet. As a step to completely develop the magnetorheological polishing (MRP) technique, this paper proposed the simulation method of MRPF based on particle dynamics, and the shear stress model of magnetorheological fluid (MRF) is optimized under the action of the magnetic field after performing the chain simulation. On the basis of the optimized shear stress model and the hexagonal close-packed structure of MRF, the holding mechanism of polishing abrasive particles is explored for the MRPF and the corresponding holding models are proposed. Then, the shear yield stress models and material removal model are also established for the inner surface polishing, respectively. Eventually, the above theoretical analysis and related models have been verified though the polishing experiment of the titanium alloy pipe.

Design and prediction simulation of an active-dispersing mechanism for magnetorheological damper with twin-tube configuration

Sedimentation immunity is one of the key features of magnetorheological (MR) dampers, which means the lifetime-long service without degradation under the sedimentation of MR fluid. In this paper, an active-dispersing mechanism is established with twin-tube configuration toward the sedimentation immunity, by adding a circulation channel powered by rotating blades between the tubes when the MR damper is not in operation. Finite element (FE) method is employed to reveal the re-dispersion process once the MR fluid settled to a specific degree, and the benefits of circulating channel and twin-tube sedimentation-immunity system for the MR fluid are discovered by the simulation. Ultimately, a self-adaptive system could be built to ensure the MR fluid in the damper keeping in a relative uniform and thus the sedimentation immunity is fulfilled.

Enhancing magneto-rheology control of cement paste through synergistic effect of nano-Fe3O4 particles and fly ash

This research examines the enhancement of magneto-rheological (MR) behavior of cement paste containing magnetic nano-Fe3O4 particles (MNPs) by the value-added utilization of fly ash. It is revealed that substituting cement with fly ash mitigates the negative impact of MNPs on the viscoelastic properties of cement paste. The early improved liquid-like behavior induced by magnetic field is significantly strengthened in cement pastes with both MNPs and fly ash. However, the increased stiffness after prolonged magnetization remains lower than that without fly ash. Replacing cement with fly ash in MNPs-containing paste shows a more significant influence on improving relative MR effect rather than absolute MR effect. Results can be concluded that partially replacing cement with magnetic fly ash is a reasonable approach to prepare highly flowable MNPs-containing cement paste with pronounced MR response.

Gyrotactic bio-magneto-convective combined impacts on magnetorheological hybrid nanoflow: Microbial life on surfaces’ application

Magnetorheological fluid with self-driven ubiquitous motile organisms was affected by various physical factors such as hydrodynamics, dispersion, and distribution of organisms. These fascinating properties attracted us to work on this paper, a Casson hybrid nanoflow model exploring the dynamic behavior of microorganisms along spongy extensible surfaces taking Ohmic heating and chemical reaction into account. Further, the heat transfer phenomena are analyzed in the presence of thermal radiation and space and time-dependent energy sources/sinks. The nanoflow has its base methanol and a mixture of iron and aluminum oxides is suspended. Flow obeying mathematical model is solved numerically using the Runge–Kutta–Fehlberg technique along with the shooting method after imposing self-similarity transformation. Results of various pertinent parameters on the flow characteristic quantities and engineering quantities are portrayed and presented through graphs and tables. Iron oxide methanol nanofluid shows supremacy over hybrid nanoflows as speed is considered, whilst the opposite phenomenon is observed in the case of energy. Hybrid nanoflow makes the surface friction-free. Microorganism concentration difference improvement also helps in the intensification of motile organism growth.

Impact Dynamics Simulation for Magnetorheological Fluid Saturated Fabric Barriers

Abstract Experimental research has investigated the non-Newtonian fluid augmentation of fabric barrier materials, aimed at adding impact energy dissipation mechanisms and thereby improving ballistic performance. Published experimental results on the effectiveness of these augmentations are mixed, and numerical models supporting complimentary modeling research are lacking, primarily due to the multiple geometric and material nonlinearities present in the system. The combination of Hamiltonian mechanics with hybrid particle-element kinematics offers a very general modeling approach to impact simulation for these systems, one which includes interstitial fluid–structure interactions, the yarn level dynamics of projectile impacts, and yarn fracture without the introduction of slidelines and without mass or energy discard. Three-dimensional (3D) impact simulations show good agreement with published experiments for magnetorheological (MR) fluid-saturated Kevlar, including fabric tested under bulk field excitation of the target region and magnetomechanically edge-clamped fabric sliding in an excited air gap. The Hamiltonian method employed to develop the system-level model allows for computationally efficient partitioning of the modeled physics while maintaining a thermodynamically consistent formulation.

Development of a Prandtl-Ishlinskii hysteresis model for a large capacity magnetorheological fluid damper

Magnetorheological (MR) fluid (MRF) dampers, serving as fail-safe semi-active devices, exhibit nonlinear hysteresis characteristics, emphasizing the necessity for accurate modeling to formulate effective control strategies in smart systems. This paper introduces a novel stop operator-based Prandtl-Ishlinskii (PI) model, featuring a reduced parameter set (seven), designed to estimate the nonlinear hysteresis properties of a large-scale bypass MRF damper with variable stiffness capabilities under varying applied current. With only seven parameters, the model realizes current, displacement, and rate dependencies. The force-displacement and force-velocity responses of the designed MRF damper were experimentally characterized under broad ranges of applied current (0–2 A), excitation frequency (0.5–4 Hz), and displacement amplitude (1–2.5 mm). A training dataset was subsequently used to develop a novel field-dependent modified PI model, incorporating multiple hysteresis operators with and without a friction element. The proposed model accurately predicted the MRF damper behavior within the training dataset, and its validity was assessed against data from diverse experimental conditions. The PI model with friction element generally outperformed the model without friction when frequency exceeds 0.5 Hz, demonstrating its ability to characterize nonlinear hysteresis force-displacement and force-velocity properties of the MRF damper under the ranges of applied current and excitations considered with reasonable accuracy. Experimental data were also estimated by the Bouc–Wen model, and compared with those obtained via the formulated PI model, affirming the overall superiority of the proposed PI models considering the computational cost, and total number of parameters. Leveraging the simplicity, minimal parameter requirements, and analytic invertibility of PI models, the proposed PI model is considered a superior choice for modeling and subsequently controlling smart structures employing MRF dampers.

Mechanism and Study on Ball End Magnetorheological Fluid Finishing Process

The primary object of this research is to explore the capacities of BEMRF. Traditional polishing methods for glass commonly face challenges in reaching nanoscale precision and uniformity. In BEMRF, by controlling rheological properties of the MR fluid, we can tackle these challenges and potentially surpass the limitations of conventional techniques. The study includes the application of magnetorheological (MR) fluid with suspended magnetic particle abrasives to accomplish precision finishing by the manipulation of magnetic fields.

Preparation and rheological properties of highly stable bidisperse magnetorheological fluids

The utilization of magnetic nanofluids as the base carrier liquid proves to be an effective strategy for enhancing the stability of magnetorheological fluids. However, the preparation method for bidispersed magnetorheological fluids still deserves further investigation. In this study, Fe3O4 nanoparticles were synthesized through chemical co-precipitation, and aviation hydraulic oil-based magnetic nanofluids were prepared using myristic acid as a surfactant. Micron-sized particles, modified with the same surfactant, were dispersed into the magnetic nanofluids, resulting in a novel bidisperse magnetorheological fluid (C-MRFF). The coated particles underwent physical phase analysis and magnetic property testing through an x-ray diffractometer, Fourier infrared spectrometer, transmission electron microscope, scanning electron microscope, and vibrating sample magnetometer. Due to the addition of nanoparticles, C-MRFFs exhibited superior stability to micron-sized particle-based magnetorheological fluids. They demonstrated the best sedimentation stability and redispersibility at a 9% mass fraction of nanoparticles. Thanks to the protection of the micron-sized particle surface coating, C-MRFFs displayed superior sedimentation stability to traditional bidisperse magnetorheological fluids over a wide temperature range. The magnetorheological properties of C-MRFFs were studied. The results indicated that the yield stress of C-MRFFs increased with increasing magnetic field strength or decreasing temperature. The increase in the mass fraction of nanoparticles was beneficial to the increase in yield stress until severe settling of C-MRFFs occurred. In comparison to micron-sized particle-based magnetorheological fluids, C-MRFFs exhibited higher yield stresses. Although the yield stress of C-MRFFs was slightly lower than that of traditional bidisperse magnetorheological fluids due to the surface coating of larger particles, they exhibited stronger shear resistance over a wide temperature range.

Design for magnetorheological dampers for protection of wires of overhead power lines

A methodology for design of magnetorheological dampers for damping vibration of overhead power lines with voltages above 110 kV is proposed, which includes a finite element model of the behavior of the working magnetorheological fluid in a hydraulic channel, and a Matlab model of dynamic processes in a loaded damper. This technique uses tables of damping coefficient values instead of the hysteretic displacement variable characteristic of the Bouc—Wen model, i.e., they use variables and parameters with a physical meaning, known at the stage of formulating of technical requirements or determined by calculations. To verify and evaluate the accuracy of the technique, a vibration model of a section of AC 150/19 wire is studied as a system with lumped parameters, suspended on garlands of intermediate support insulators using magnetorheological dampers. Keywords:magnetorheological damper, wire, vibration, overhead power lines, Matlab, diagram, magnetorheological fluid acidwolfvx@rambler.ru, erof.vi@yandex.ru, ilyatishin41.45@gmail.com

Deep-Learning-Based Strong Ground Motion Signal Prediction in Real Time

Processing ground motion signals at early stages can be advantageous for issuing public warnings, deploying first-responder teams, and other time-sensitive measures. Multiple Deep Learning (DL) models are presented herein, which can predict triaxial ground motion accelerations upon processing the first-arriving 0.5 s of recorded acceleration measurements. Principal Component Analysis (PCA) and the K-means clustering algorithm were utilized to cluster 17,602 accelerograms into 3 clusters using their metadata. The accelerograms were divided into 1 million input–output pairs for training, 100,000 for validation, and 420,000 for testing. Several non-overlapping forecast horizons were explored (1, 10, 50, 100, and 200 points). Various architectures of Artificial Neural Networks (ANNs) were trained and tested, such as Convolutional Neural Networks (CNN), Recurrent Neural Networks (RNN), Long Short-Term Memory (LSTM) networks, and CNN-LSTMs. The utilized training methodology applied different aspects of supervised and unsupervised learning. The LSTM model demonstrated superior performance in terms of short-term prediction. A prediction horizon of 10 timesteps in the future with a Root Mean Squared Error (RMSE) value of 8.43 × 10−6 g was achieved. In other words, the LSTM model exhibited a performance improvement of 95% compared to the baseline benchmark, i.e., ANN. It is worth noting that all the considered models exhibited acceptable real-time performance (0.01 s) when running in testing mode. The CNN model demonstrated the fastest computational performance among all models. It predicts ground accelerations under 0.5 ms on an Intel Core i9-10900X CPU (10 cores). The models allow for the implementation of real-time structural control responses via intelligent seismic protection systems (e.g., magneto-rheological (MR) dampers).

A Soft Variable Stiffness Gripper with Magnetorheological Fluids for Robust and Reliable Grasping

A Soft Variable Stiffness Gripper with Magnetorheological Fluids for Robust and Reliable Grasping