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The applications of magneto-rheological fluids have become many, and important. Especially the valves used in dampers and hydraulic systems. Including the pressure relief valve. But all of these valves are type normally open. However, the pressure relief valve should be of the normally closed type. This study presents the concept of a magneto-rheological pressure relief valve using a permanent magnetic, along with a comprehensive analysis. Using FEMM software the design analysis was performed, to determine the efficiency of its performance and work. As a result of the work, the appropriate current value was determined, which is 0.17 amps, along with the number of turns of the electric coil, the best of which was 240 turns, which was applied to open the valve at the appropriate pressure. The maximum pressure was about 2500 kPa, which can be tolerated in the valve also calculated. Through the analysis, it was also determined that 1 mm is the best thickness for the gap. As well as choose the type and dimension of the proper permanent magnet. With this work, the design is considered very suitable and efficient, and it can be developed in the future based on the same principle and method. [ABSTRACT FROM AUTHOR]

Grippers are commonly used as a technological tooling for manipulators. They enable robots to interact with objects in their work area. Grippers have a wide range of differentiation focused on the operation performed and the properties (e.g. shape) of the object being gripped. Their design and functionality are constantly being modified, tuned and developed by both academic and industrial units. Consequently, this paper presents a proposal for a lightweight jaw using MR fluid, which can be implemented in a jaw gripper (e.g. Robotiq 2F-140) to form a hybrid soft-rigid structure. In addition, methods are presented for studying the use of soft structures in a jaw gripper. As part of the work carried out, a model of the cushion and jaw of the gripper was developed, the FEM was used to obtain the character of the deformation when the object is axially plunged into it. Experimental plunging tests as well as dynamic tests of object transfer were also carried out. The work carried out allowed to demonstrate several key aspects of the grippers area. The soft structures of the grippers should be studied in terms of the force required to deform them. This determines their applicability to fragile and deformable objects. Dynamic measurements of the handling of objects of different shapes, with simultaneous measurement of force, allow the effectiveness of the use of soft structures in the gripper to be determined. Such experiments will make it possible to determine the measurable stability and repeatability of the grasp. The results of the research and experiments will be particularly applicable to robotic arms with relatively low lifting capacity. [ABSTRACT FROM AUTHOR]

Magnetorheological (MR) fluids can be utilized in one of the fundamental operating modes of which the gradient pinch mode has been the least explored. In this unique mode non-uniform magnetic field distributions are taken advantage of to develop a so-called Venturi-like contraction in MR fluids. By adequately directing magnetic flux the material can be made solidified in the regions near the flow channel wall, thus creating a passage in the middle of the channel for the fluid to pass through. This leads to unique variations of the slope in the pressure-flow rate characteristics. It can be stated that the effect of the MR fluid composition on the behaviour of the MR fluid in gradient pinch mode has not been thoroughly investigated yet. In this study, the behaviour of MR fluids was assessed with a dedicated pinch mode MR valve that provided a valuable insight into the contraction mechanism using fluorescence microscopy. Briefly, seven MR fluid samples were prepared with different particle concentrations (10%, 22% and 32 vol%) and mean particle sizes (2, 4.5 and 8.2 μm). It was found that the MR fluid sample with the larger particle size exhibits a significantly larger slope change observed in the pressure-flow rate characteristics. Increasing the particle size from 2 μm (base) to 8 μm resulted in the slope increase by a factor of 2.6 compared to the base sample. Increasing the particle concentration has a negligible effect on the pinch mode effect. Finally, these results were analysed using the modified Wuest equation, which is commonly used for characterizing sharp-edged orifices in low Reynolds number flow regimes. The simple equation was determined to describe the behaviour of MR fluids in gradient pinch mode with adequate accuracy. [ABSTRACT FROM AUTHOR]

AbstractThis research examines the dynamic characteristics of laminated composite sandwich plates with magnetorheological elastomer (MRE) and graphene-reinforced MRE (hybrid-MRE) cores. The laminated composite was fabricated with unidirectional glass fiber with [0°/90°]s ply orientation, epoxy resin (LY556), and hardener (HY951) using a vacuum bagging-assisted hand-layup technique. The experiment was performed to determine the natural frequencies of the sandwich plates under clamped-clamped (CC) boundary conditions with various magnetic fields. The laminated composite sandwich plate with MRE and graphene-reinforced MRE was developed by using Abaqus, and the results are validated with experimental results and existing literature. Further, the MRE and graphene-reinforced MRE sandwich plates parametric study evaluates the impact of the applied magnetic field, ply orientation, different boundary conditions, aspect ratio, and core-skin layer thickness ratio. Under clamped-free (CF) boundary conditions, The MRE and hybrid-MRE sandwich plate natural frequencies exhibit an increase of 14.64% and 16.27%, respectively, as the applied magnetic field increased from 0 G to 750 G. The MRE and hybrid-MRE sandwich plates demonstrate their highest natural frequencies under CC conditions and [0°]4 ply orientation, in contrast to other boundary conditions and ply orientations. The sandwich plate’s natural frequencies decrease with an increase in both the core-skin thickness ratio and aspect ratio. This research will guide design engineers in replacing pure MRE with hybrid MRE in certain aerospace applications. [ABSTRACT FROM AUTHOR]

Purpose: With the advantages of simple structure, low energy consumption, and wide controllable damping range of magnetorheological (MR) damper, semi-active suspension with MR damper has become a promising application in the existing vehicle suspension system. However, the response time of MR fluid, the operation time of control system and the driving time of MR damper will result in response time delay together, which severe affect the vibration attenuating performance of the vehicle semi-active suspension system with MR damper. In this paper, a LQR controller incorporating NAGA-II algorithm considering response time delay (NSGA-II-TLQR) was developed to compensate for the response time delay of vehicle semi-active suspension system. Methods: Firstly, the mechanical property experiments of MR damper were carried out, and the direct model and the inverse model of MR damper were established by using genetic algorithm, respectively. Secondly, the model of a two-degree-of-freedom (2DOF) quarter vehicle semi-active suspension system with MR damper was built. Subsequently, the NSGA-II algorithm was introduced to optimize the weighting coefficient matrix of the LQR controller. Then the first-order Taylor series expansion was applied to the NSGA-II-LQR controller to predict the control force, which compensate for the response time delay. Finally, the performance was verified by simulation and experimental tests. Results: The results show that the body acceleration RMS values with NSGA-II-TLQR controller are decreased by 15.5% and 4.48%, the suspension deflection RMS values are decreased by 22.54% and − 1.22%, and the tire dynamic load RMS values are decreased by 10.32% and 5.38% compared with the passive suspension and the suspension with NSGA-II-LQR controller, respectively. Conclusions: The semi-active suspension with NSGA-II-TLQR controller has better performance in the ride comfort and handling stability. [ABSTRACT FROM AUTHOR]

The integration of surfactants and nanoparticles in emulsion formulations has attracted significant attention due to their potential synergistic effects, improving stability and enabling the development of stimuli-responsive materials. The objective of this study was to investigate the stability, bulk rheological, and magnetorheological properties of oil in water (o/w) emulsions, composed of Fe3O4 kerosene-based ferrofluids dispersed in surfactant solutions (hexadecylpyridinium chloride, and nonylphenol polyethoxylate—ethylene oxide = 40, known as Tergitol NP-40), as a function of concentration and nature of the emulsifying agents. The results demonstrated the formation of stable systems (>2 months), featuring an average droplet size below 4 μm, with the primary stabilization mechanism attributed to the reduction of interfacial tension by surfactant activity. The emulsions exhibited shear thinning and viscoelastic solid-like behavior, which were enhanced by increasing the concentrations of both emulsifiers. Emulsions stabilized with hexadecylpyridinium exhibited a higher structural rigidity, with dynamic moduli an order of magnitude higher than Tergitol formulations. In the presence of a perpendicular magnetic field, it was demonstrated that incorporating ferrofluid as a dispersed phase in an o/w emulsion potentiates the magnetoviscous effect, compared to that observed with neat ferrofluid at the same concentration. A maximum relative increase in viscosity of up to 17-fold was observed in emulsions stabilized with 2.5 w/v% of hexadecylpyridinium and 10 000 ppm of nanoparticles when exposed to a linearly increasing magnetic field up to 796.73 mT at 1 s−1. The observed magnetoviscous effect remained reproducible for up to one year after formulation, highlighting the potential of these systems for multiple applications. [ABSTRACT FROM AUTHOR]

Magnetorheological (MR) fluids are utilized to develop a variety of electromechanical devices that have potential applications in the automotive, medical, aerospace, and other areas. Since yield stress is the most important design parameter of an MR fluid and its devices, it is dependent on the types of operational modes. This paper thoroughly examines the effects of the operational modes of MR fluids such as shear mode, and squeeze mode along with the impact of mixed-mode operation on the performance of MR fluids and devices. The study found that mixed-mode operation results in higher yield stress and offers better performance control for MR fluid devices compared to single-mode operation under the same working conditions. Several factors impact the performance of MR fluid devices in various operational modes discussed in the paper such as geometry, initial gap thickness, temperature, pressure, velocity, applied compressive strain, response time, magnetic particle composition, magnetic field, and other working factors. Therefore, there is a necessity to thoroughly examine the rheological and mechanical behaviors of MR fluids and the performance of MR devices in different operational modes and working circumstances, highlighting the experimental and theoretical findings conducted by researchers. [ABSTRACT FROM AUTHOR]

As an intelligent transmission device, the magnetorheological (MR) clutch cannot realize its accurate torque control because it is difficult to establish its accurate torque control mathematical model. This paper designs a squeeze shear MR clutch. In order to achieve accurate torque control of the MR clutch, this paper proposes a fuzzy proportional integral differential (PID) control strategy based on the optimization of the bee colony algorithm. Based on the mechanical transmission experiment platform of the MR clutch, the performance of the torque control of the MR clutch is experimentally studied by using the real-time operating system Phar Lap ETS built by LabVIEW real-time module, it is found that the fuzzy PID control strategy based on bee colony algorithm can not only improve the torque control accuracy of the MR clutch by 70% compared to traditional PID control strategies but also increase the response speed by more than 50%. [ABSTRACT FROM AUTHOR]

Non-Newtonian behaviour of the Magnetorheological (MR) fluid under the influence of external magnetic field can be commissioned to design various applications such as MR brake, damper, and clutches, etc. Better design strategies, material selection and characterization led to realize the potential of MR brakes to replace conventional brakes. The present study emphasises on developing lightweight (1.8 kg) multi-rotor MR brake (MMRB). Finite element method magnetics (FEMM) software is utilized to determine the material required for a single-rotor MRB. FEMM material selection analysis is incorporated into the modeled MMRB, and the nature of magnetic flux density throughout the MR gap was obtained. Magnetic circuit analysis of the proposed brake is carried out to find torque estimation using analytical equations and Bingham plastic model. The proposed brake is fabricated and characterized using commercial MRF (132 DG, Lord Corporation). The study compares the torque outputs obtained experimentally with finite element analysis (FEA) and analytical approach. The average maximum magnetic flux density through FE analysis is found to be 0.45 T @ 3 A current. The average error between FE obtained and experimentally obtained torque output of the brake is around 5%. Further, an alternate design is proposed by utilizing same rotor diameter and number of electromagnetic coils. The new design is lighter in weight (0.8 kg) and exhibits enhancement in the torque output and torque to weight ratio by around 31% and 55%, respectively than the present design. [ABSTRACT FROM AUTHOR]

Torque density, torque range and response time are the problems to be solved urgently in the field of magnetorheological (MR) transmission. To improve the torque, the most frequently used techniques are increasing the effective area and magnetic field strength of MR fluids, such as multiple gaps and multiple coils designs. This paper proposed a multi-drum MR brake with side-set dual-coil. First, a structure description of the multi-drum MR brake is presented. The torque and torque density models are established. Then, an approximate optimization is conducted to obtain the optimal values for main dimensional parameters. Finally, a brake prototype is manufactured and the performance is validated. Experimental results indicate that the maximum torque is 6.8 N m, and the torque density is 37.866 kN m−2 when the two magnetic fields are superimposed together. Different torque capability and torque density can be gained by controlling the magnitude and direction of input current of the two coils. The results indicate that the torque capacity, torque density and torque range can be improved by the two coils. Furthermore, it can be concluded that the coil current has little effect on the transient time while the rising time is affected by the rotational speed. [ABSTRACT FROM AUTHOR]

A multi-objective intelligent optimization algorithm-based attitude control strategy for magnetorheological semi-active suspension is proposed to address the vehicle attitude imbalance generated during steering and braking. Firstly, the mechanical properties of the magnetorheological damper (MRD) are tested, and the parameters in the hyperbolic tangent model of the magnetorheological damper are identified through experiments. Secondly, a simulation model of the whole vehicle multi-degree-of-freedom vehicle dynamics including magnetorheological damper is established, and the whole-vehicle Linear Quadratic Regulator (LQR) controller is designed. Then, the optimization design model of the joint vehicle controller and vehicle dynamics is established to design the optimization fitness function oriented to the body attitude control performance, and the attitude optimal controller is calculated with the help of multi-objective intelligent optimization algorithm. Simulation results show that the proposed control method is able to improve the body roll angle, body pitch angle, and suspension dynamic deflection well on the basis of ensuring no deterioration in other performance indexes, ensuring good attitude control capability of the vehicle and verifying the feasibility of the control strategy. [ABSTRACT FROM AUTHOR]

This work aims to accurately evaluate the nonlinear behaviors of the vane-type magnetorheological (MR) damper through multi-physics field coupling analysis. The working principle of the vane-type MR damper is introduced, and the output torsion model is derived. Considering that the performance of the MR damper is affected by the coupling of electromagnetic field, flow field, thermal field, and solid mechanics, the finite element software COMSOL is used to simulate the multi-physics field inside the MR damper. Correspondingly, the mechanical performance testing of the MR damper is carried out on the torsional electro-hydraulic servo fatigue testing machine. The test results show that the MR damper can reach a maximum output torsion of 7130 N·m and achieves a high torsion-volume ratio of 4.19 × 107 N·m−2, which proves that it has good mechanical properties as well as the ability to satisfy high torsional requirements in relatively limited space. Finally, a comparative analysis between the simulation and experimental curves is carried out, and it is concluded that the multi-physics field coupling analysis can accurately simulate the mechanical performance and working state of the vane-type MR damper. [ABSTRACT FROM AUTHOR]

This study examines the three-axis vibration isolation capabilities of a full-scale magnetorheological (MR) seat suspension system utilizing experimental methods to assess performance under both single-axis and simultaneous three-axis input conditions. To achieve this, a semi-active MR seat damper was designed and manufactured to address excitations in all three axes. The damper effectiveness was tested experimentally for axial and lateral motions, focusing on dynamic stiffness and loss factor using an MTS machine. Prior to creating the full-scale MR seat suspension, a scaled-down version at one-third size was developed to verify the damper's ability to effectively reduce vibrations in response to practical excitation levels. Additionally, a narrow-band frequency-shaped semi-active control (NFSSC) algorithm was developed to optimize vibration suppression. Ultimately, a full-scale MR seat suspension was assembled and tested with a 50th percentile male dummy, and comprehensive three-axis vibration isolation tests were conducted on a hydraulic multi-axis simulation table (MAST) for both individual inputs over a frequency range up to 200 Hz and for simultaneous multi-directional inputs. The experimental results demonstrated the effectiveness of the full-scale MR seat suspension in reducing seat vibrations. [ABSTRACT FROM AUTHOR]

AbstractAiming at the problem of the suspension isolator not being able to adjust the damping, magnetorheological damping technology was introduced based on the traditional rubber passive suspension. A magnetorheological (MR) fluid damper was designed inside the rubber suspension and connected with the rubber structure to form a magnetorheological fluid-elastomer (MRFE) damper. The design principle of the MR damper was described. The principle prototype of the initial MRFE damper was designed, and the mechanical properties of the damper were tested through experiments. Taking the damping force, dynamic adjustable range and power as the optimization objectives, the structure of the MR damper was optimized using the non-dominated sorting genetic algorithm II (NSGA-II). The Pareto optimal solution set of MR damper parameters was obtained, and the structural parameters of the MR damper were determined based on the principle of minimum response time. A multi-physics field simulation model of the optimal damper was established to analyze the dynamic performance of the MR damper. The principle prototype of the optimal MRFE damper was obtained, and the optimal MR damper increased the damping force by 63.1% and the dynamic adjustable range by 104.9% compared with the initial MR damper, while the optimal MRFE damper increased the damping force by 9.27% and the dynamic adjustable range by 8.85% compared with the initial MRFE damper. The design results meet the requirements, and the proposed optimization method can provide a theoretical basis for the optimal design of related vibration-damping equipment. [ABSTRACT FROM AUTHOR]

In recent years, the application of non-uniform pressure in flexible-die forming, such as viscous pressure forming and magnetorheological pressure forming, has become increasingly prevalent in manufacturing thin-walled components. Non-uniform pressure is primarily employed to change the shape of the sheet, while its effects on thickness reduction and fracture behaviors remain intricate. In this study, the mechanisms of non-uniform pressure to decrease thickness reduction and delay fracture instability in bulge forming are revealed. Non-uniform pressure changes the principal stresses, resulting in distinct deformation behaviors. Numerical simulations indicate that both too large and too small pressure weights lead to severe thickness thinning and increase the risk of fracture instability. Theoretical equations of the polar strain and instability strain are derived to reveal the mechanisms. The characteristics of non-uniform pressure to decrease thickness reduction and delay instability are outlined. Viscous pressure bulge tests are conducted, and the experimental results of bulged shapes, thickness uniformity, polar strains, and instability behaviors validate the theories. The fracture strain under the non-uniform pressure condition shows a 5.6% increase compared with the uniform pressure condition. This study proves that non-uniform pressure can promote sheet formability, suggesting promising applications in sheet metal forming. [ABSTRACT FROM AUTHOR]

A novel magnetorheological vibration isolator with two operating conditions, horizontal shear and vertical compression, was designed and manufactured. The rheological properties of the energy-dissipating material were directly related to the volume fraction of iron powder in the laminated working unit of the magnetorheological vibration isolator. Aggregation of the carbonyl iron powder (CIP) strongly influenced on the rheological properties of the magnetorheological vibration isolator. Considered that the curing temperature affected the preparation process, polyurethane rubber was selected as the collective matrix of the magnetorheological elastomer (MRE) because of its wear resistance, good adhesion, high strength, corrosion resistance and solvent resistance. The dynamic properties of the polyurethane rubber MREs were experimentally characterised. A mathematical model was established for the magnetic induction effect (MIE) of the polyurethane magnetorheological isolator in a transverse shear deformation mode as well as a vertical tension and compression deformation mode. The magnetorheological effect was strongest under transverse shear deformation for an effective volume fraction of particles of 34% because of the effect of aggregation of the iron powder particles. The magnetic compression modulus depended strongly on the strain under vertical compression. [ABSTRACT FROM AUTHOR]

Magnetorheological elastomers (MREs) are innovative materials composed of ferromagnetic particles embedded within a polymer matrix, enabling real‐time tunability of mechanical properties through external magnetic fields, thereby generating pronounced mechanical‐magnetic coupling effects. However, the mechanical performance of MREs, particularly their load‐bearing capacities under dynamic conditions, remains constrained by the limitations of conventional matrix materials. In this study, shear‐stiffening gel (SSG), exhibiting viscoelastic mechanical behavior, is incorporated into magnetorheological elastomers to develop magnetorheological shear‐stiffening elastomer (MSSE) through a high‐temperature and high‐pressure vulcanization process. The mechanical‐magnetic coupling behavior of these composites is systematically evaluated utilizing a series of mechanical experiments across varying strain rates. Notably, the interaction between carbonyl iron particles (CIPs) and the molecular chains within the shear‐stiffening matrix significantly enhanced the magnetorheological effects of MSSEs, particularly under dynamic impact loadings. Leveraging the adjustable modulus of MSSEs and drawing inspiration from the microstructural characteristics of beetle exoskeletons, a beam‐structured 3D buffer device is designed. This device demonstrates superior energy absorption capacity, underscoring its potential for advanced flexible protection applications. [ABSTRACT FROM AUTHOR]

Vehicles experience various frequency excitations from road surfaces. Recent research has focused on active dampers that adapt their damping forces according to these conditions. However, traditional magnetorheological (MR) dampers face a "block-up phenomenon" that limits their effectiveness. To address this, additional flow-type MR dampers have been proposed, although revised designs are required to accommodate changes in damping force characteristics. This study investigates the damping performance of MR dampers with an additional flow path to enhance the vehicle ride quality. An optimization model was developed based on fluid dynamics equations and analyzed using electromagnetic simulations in ANSYS Maxwell software. Vibration analysis was conducted using AMESim by applying a sinusoidal road surface model with various frequencies. Results show that the optimized diameter of the additional flow path obtained from the analysis was 1.1 mm, and it was shown that the total damping force variation at low piston velocities decreased by approximately 56% compared to conventional MR dampers. Additionally, vibration analysis of the MR damper with the optimized additional flow path diameter revealed that at 30 km/h, 37.9% acceleration control was achievable, at 60 km/h, 18.7%, and at 90 km/h, 7.73%. This demonstrated the resolution of the block-up phenomenon through the additional flow path and confirmed that the vehicle with the applied damper could control a wider range of vehicle upper displacement, velocity, and acceleration compared to conventional vehicles. [ABSTRACT FROM AUTHOR]

This paper proposes a novel design method for a magnetorheological (MR) damper-based semi-active suspension system. An improved MR damper model that accurately describes the hysteretic nature and effect of the applied current is presented. Given the unfeasibility of installing sensors for all vehicle states, an MR damper current controller that only considers the suspension deflection and deflection rate is proposed. A linear matrix inequality problem is formulated to design the current controller, with the objective of enhancing ride safety and comfort while guaranteeing vehicle stability and robustness against any road disturbance. A series of experiments demonstrates the enhanced performance of the proposed MR damper model, which exhibits greater accuracy than other state-of-the-art damper models, such as Bingham or bi-viscous. An evaluation of the vehicle behavior under two simulated road scenarios has been conducted to demonstrate the performance of the proposed output feedback MR damper-based semi-active suspension system. [ABSTRACT FROM AUTHOR]

Improving the dynamic rheological properties of magnetorheological shear thickening fluid is beneficial to its improved application in dampers. In this work, we mixed silicon dioxide (SiO2), carbonyl iron powder (CIP), and sepiolite (Sep) into polyethylene glycol to prepare a novel sepiolite magnetorheological shear thickening fluid (MR-Sep/STF). The dynamic rheological properties of the MR-Sep/STF and stress attenuation were studied through orthogonal array testing. Specifically, we mean that using this experimental design to evaluate the effects of varying proportions of SiO2, CIP, and Sep on the damping factor, dynamic yield stress, and shear thickening effect. The excellent performance of the MR-Sep/STF was achieved at an optimal ratio of 55% SiO2, 10% CIP, and 2% Sep. In addition, stress attenuation tests indicated that when the shear rate was within the range of 30–40 s−1, the stress attenuation is roughly between 42.85% and 59.78%. Once the shear rate exceeded 40 s−1, the stress decreased by more than 300%. Furthermore, we proposed a structural kinetics constitutive model that offers profound insight into the dynamic response mechanisms of the MR-Sep/STF: at the maximum shear rate, the structure generation rate a has a maximum value. Once maximum shear rate is exceeded, the structure decomposition rate b is greater than the generation rate a, and the viscosity and stress decrease macroscopically. [ABSTRACT FROM AUTHOR]

This paper presents the design process of a magnetorheological elastomer (MRE) absorber with a shear symmetric structure based on detailed simulation and experiments. First, the MRE materials and dimensional parameters of the MRE absorber are determined, and magnetic field simulation is performed to analyze the magnetic induction performance in the working area. Then, a dynamic simulation model is constructed to analyze the frequency response characteristics of a semi-active vibration system. Finally, a vibration experimental platform is built to test the response performance of the shear-mode MRE absorber. The experimental results showed that the stiffness of the MRE absorber can be effectively adjusted by current. When the applied current changes from 0.5 to 2 A, a vibration reduction frequency band of 8.91 to 14.19 Hz will be formed. The closer the natural frequency in this frequency band is to the external excitation frequency, the better the vibration reduction effect, which verifies the effectiveness of semi-active vibration control for the primary system. These results validate the rationality and feasibility of the semi-active MRE absorber, providing a good reference for the design of MRE absorbers. [ABSTRACT FROM AUTHOR]

To improve the characteristics of traditional model predictive control (MPC) semi-active suspension that cannot achieve the optimal suspension control effect under different conditions, a variable horizon model predictive control (VHMPC) method is devised for magnetorheological semi-active suspension with air springs. Mathematical models are established for the magnetorheological dampers and air springs. Based on the improved hyperbolic tangent model, a forward model is established for the magnetorheological damper. The adaptive fuzzy neural network method is used to establish the inverse model of the magnetorheological damper. The relationship between different road excitation frequencies and the control effect of magnetorheological semi-active suspension with air springs is simulated, and the optimal prediction horizons under different conditions are obtained. The VHMPC method is designed to automatically switch the predictive horizon according to the road surface excitation frequency. The results demonstrate that under mixed conditions, compared with the traditional MPC, the VHMPC can improve the smoothness of the suspension by 2.614% and reduce the positive and negative peaks of the vertical vibration acceleration by 11.849% and 6.938%, respectively. Under variable speed road conditions, VHMPC improved the sprung mass acceleration, dynamic tire deformation, and suspension deflection by 7.191%, 7.936%, and 22.222%, respectively, compared to MPC. [ABSTRACT FROM AUTHOR]

Magnetorheological elastomers (MREs) are in demand in the field of high-tech microindustries and nanoindustries such as biomedical applications and soft robotics due to their exquisite magneto-sensitive response. Among various MRE applications, programmable actuators are emerging as promising soft robots because of their combined advantages of excellent flexibility and precise controllability in a magnetic system. Here, we present the development of magnetically programmable soft magnetic microarray actuators through field-induced injection molding using MREs, which consist of styrene-ethylene/butylene styrene (SEBS) elastomer and carbonyl iron powder (CIP). The ratio of the CIP/SEBS matrix was designed to maximize the CIP fraction based on a critical solids loading. Further, as part of the design of the magnetization distribution in micropillar arrays, the magnetorheological response of the molten composites was analyzed using the static and dynamic viscosity results for both the on and off magnetic states, which reflected the particle dipole interaction and subsequent particle alignment during the field-induced injection molding process. To develop a high-aspect-ratio soft magnetic microarray, X-ray lithography was applied to prepare the sacrificial molds with a height-to-width ratio of 10. The alignment of the CIP was designed to achieve a parallel magnetic direction along the micropillar columns, and consequently, the micropillar arrays successfully achieved the uniform and large bending actuation of up to approximately 81° with an applied magnetic field. This study suggests that the injection molding process offers a promising manufacturing approach to build a programmable soft magnetic microarray actuator. [ABSTRACT FROM AUTHOR]

Sandwich structures are widespread in engineering applications because of their advantageous mechanical properties. Recently, their acoustic performance has also been improved to enable attenuation of low-frequency vibrations induced by noisy environments. Here, we propose a new design of sandwich plates (SPs) featuring a metamaterial core with an actively tunable low-frequency bandgap. The core contains magnetorheological elastomer (MRE) resonators which are arranged periodically and enable controlling wave attenuation by an external magnetic field. We analytically estimate the sound transmission loss (STL) of the plate using the space harmonic expansion method. The low frequency sound insulation performance is also analyzed by the equivalent dynamic density method, and the accuracy of the obtained results is verified by finite-element simulations. Our results demonstrate that the STL of the proposed plate is enhanced compared with a typical SP analog, and the induced bandgap can be effectively tuned to desired frequencies. This study further advances the field of actively controlled acoustic metamaterials, and paves the way to their practical applications. [ABSTRACT FROM AUTHOR]

The utilisation of chemical-assisted methods is considered an effective approach for enhancing the efficiency of magnetorheological polishing (MRP) and surface quality of optoelectronic wafers. However, these methods may result in corrosion of the magnetorheological components, thereby complicating the oxidation of next-generation optoelectronic wafers. To address this challenge and ensure both efficient chemical oxidation and stable mechanical removal ability in chemical-assisted MRP (CMRP), a novel technique was proposed, termed photoelectro-Fenton composite MRP (PEMRP). This method involves the application of an electric field to decrease the probability of extinction of the photo-generated electron‒hole pairs, thereby augmenting the ·OH generation rate. Additionally, a light field was utilised to decompose the iron flocculent produced by the electric Fenton system into Fe2+ ions, while enhancing the regeneration rate of H 2 O 2 to maintain the stability of the electrochemical reaction. Moreover, carbonyl iron particles (CIPs) were employed to electrocatalytically ionise Fe2+ ions and convert Fe3+ ions into Fe2+. Analysis of the changes in the polishing slurry components and polishing experiments conducted under varying external fields revealed that Fe2+ depletion was rapidly induced by a single electric field, leading to an increase in the Fe3+ concentration and the generation of iron flocs. Conversely, under a single light field, the surface-temperature of the workpiece increased, potentially causing an iron oxide layer to adhere to the surface, thereby hindering material removal. However, under the influence of the photoelectric composite field, a synergistic chemical effect was induced by the combination of CIPs and TiO 2 , resulting in an efficient Fe2+ regeneration rate (the post-experiment Fe2+ concentration increased by 220.32 %, with Fe2+ comprising 93 % compared to the initial 80 %). Consequently, the highest ·OH generation rate was achieved under these conditions (the degradation rate of methyl orange stabilised at 96.8 % within 10 min), along with improved polishing efficacy (the material removal rate increased by 70.77 % (to 13.32 mg/h) and the surface roughness decreased by 30.29 % (to 4.35 nm)). [ABSTRACT FROM AUTHOR]

Due to the distinctive working environment of high precision machining and manufacturing field, it poses challenges in meeting the isolation requirements, including limited installation space, multi-dimensional vibration, and a wide range of vibration frequencies. To tackle these obstacles, this paper introduces a magnetorheological (MR) isolator that offers adjustable vertical damping characteristics while guaranteeing three-axis vibration isolation through an inclined cone structure. First, the structure of the isolator was designed by combining a flow valve damper with a conical rubber structure. Second, in pursuit of lightweight design and enhanced magnetic field strength, collaborative simulations using ANSYS and Maxwell are conducted to subject the critical components of the isolator to multi-objective optimization. The optimization results demonstrate that the mass of the isolator has been reduced by approximately 27.7%, while the magnetic field intensity has increased by around 20%. Finally, the performance of the MR isolator was verified through static testing and dynamic testing, respectively. The experimental results demonstrate that the isolator can generate a maximum damping force of approximately 778 N when exposed to a current of 1.5 A. Compared to the initial value of 445.06 N at 0 A, there has been an approximate increase of 1.74 times. [ABSTRACT FROM AUTHOR]

The sedimentation measurement is of significant importance when designing and synthesizing magnetorheological (MR) fluid for engineering applications. Generally, visual observation is always used to discern the mud line position but knows nothing about the concentration distribution under the mud line. The method using electromagnetic scanning is limited by the position resolution because of the height of the inductor, and the method based on thermal conductivity is time-consuming and determines the sedimentation status at a specific location. In this paper, the sedimentation behavior is revealed by the laser transmittance intensity (LTI) method which is based on scattering when the light passes through the MR fluid, the higher the concentration and the stronger the scattering, the weaker the received light intensity. Specifically, the laser diode and the photodiode were utilized as the light source and receiver, respectively. MR fluid samples in a series of concentrations are used to obtain the correlation between volume fraction and photodiode output voltage, and that is taken as the calibration of the sensing method. In the experiments, the scanning with height and the sensing with time are jointly employed to characterize the settling process of a specific MR fluid. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The plastic deformation of the complex thin-walled components is not uniform. Applying a non-uniform load can decrease the thickness reduction and improve the thickness uniformity. In recent years, the application of non-uniform pressure to deform the sheet (such as magnetorheological pressure forming and viscous pressure forming) has attracted researchers' attention. However, the characteristics of the non-uniform pressure have not been researched. Control of the non-uniform pressure in the forming process lacks theoretical support. In this study, the mechanism of the non-uniform pressure in the viscous pressure bulge test is investigated. The pressure-carrying medium, called viscous medium, is semi-solid and flowable. The inhomogeneous flow behavior of the medium produces non-uniform pressure when the maximum is at the bulged pole. The inhomogeneous deformation behavior of the medium produces non-uniform pressure when the minimum is at the bulged pole. The effects of flow and deformation are opposite. The non-uniform pressure function is derived, and the evolution of the pressure is presented. During forming, the viscosity of the medium increases with the pressure, so the effect of the flow behavior increases, and the pressure weight at the pole increases. Viscous pressure bulge tests are carried out to verify the theory. The gradient and evolution of the pressure can be controlled by the loading velocity and the property of the medium. The results provide theoretical guidance for the control of the pressure in viscous pressure forming, and the methodology is expected to analyze the non-uniform pressure in other flexible die forming processes. [ABSTRACT FROM AUTHOR]

In order to reveal adsorption-regulation micromechanism and debonding micromechanism between wall surface and magnetorheological (MR) wall-climbing robot legs, an interparticle normal magnetic attraction (NMA) mechanics model was constructed based upon the magnetic-dipole theory. According to analysis of NMA mechanics, it was confirmed that the interparticle NMA could be intensified with enhancing magnetic-particle diameter but was weakened with ratio of adjacent magnetic-particles distance to magnetic-particle radius. It means that the adhesive capacity between MR wall-climbing robot legs and wall surface could be strengthened by increasing magnetic-particle size and decreasing interparticle distance. Furthermore, it was found that the NMA of the first particle in the magnetic chain was positively related to magnetic-particles number until the magnetic-particles number reached a critical value. Consequently, the adsorption ability between MR wall-climbing robot legs and wall surface could be effectively controlled by changing magnetic-particles number. Besides, the strongest NMA appeared at the middle of the magnetic chain. However, the weakest NMA locates at both ends of the magnetic chain. Thus, it could be concluded that the end of the magnetic chain would be separated from wall surface rather than fracture occurred in the middle of the magnetic chain when the MR wall-climbing robot legs divorced from wall surface. [ABSTRACT FROM AUTHOR]

Silicon carbide (SiC) substrates are widely used in semiconductor and photoelectric applications due to excellent electrical and chemical properties. However, due to its inherent hard-brittle properties and chemical inertness, traditional polishing processes are facing great challenges to obtain excellent surface and subsurface quality for the SiC substrates. In this work, a novel polishing process i.e. magnetorheological shear thickening polishing (MRSTP) was proposed to explore the feasibility for the polishing of the SiC substrates. The MRSTP experiments were conducted using multiple magnetic-pole-coupled tools. The magnetic field characteristics of the polishing area were investigated via finite element simulation and actual measurements. The magnetic-pole-coupled tool was capable of generating high magnetic induction strength in the polishing area. The MRSTP medium was designed and prepared. The media were formed magnetic brushes by the excited magnetic field. The MRSTP experiments were conducted to investigate the effects of processing parameters on the polished surface roughness. The optimum process parameters were determined as the spindle rotational speed of 700 rpm, the feed rate of 600 mm/min, the work gap of 0.5 mm and MRSTP media CIPs particle size of 100 μm. The surface roughness of the workpieces was improved from initial 1.414 μm to 27.6 nm. It is verified that the MRSTP is the feasible ultraprecision polishing process for the SiC substrates. [ABSTRACT FROM AUTHOR]

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AbstractSeismic uplift of a high-speed rail (HSR) cable-stayed bridge’s bearing affects train safety. Existing technique lacks improved seismic isolation in the vertical direction due to the bearing’s vertical stiffness. Based on the on-site dynamic test and train derailment table experiments and different software, the train running safety of the semi-floating system of the cable-stayed bridge-rail-train system was analyzed using different damping and isolation control strategies. The larger vertical seismic component increases the danger of flange climb derailment when subjected to near-fault earthquakes. After installing lateral/or viscous fluid dampers (VFDs) and magnetorheological (MR) bearing (A = 3.0), the bridge has an obvious bearing uplift response. Still, it is not enough to threaten the structure, and the seismic damping capacity of the bridge structure is improved, making the train ride safe. This research presents discoveries on the impact of bearing uplift on train operational safety. Specifically, it reveals that the lifting of the end bearings on both sides of the main girder is not synchronized. This investigation presents a technical reference for comparable initiatives. [ABSTRACT FROM AUTHOR]

Flexible grippers are a promising and pivotal technology for robotic grasping and manipulation tasks. Remarkably, magnetorheological (MR) materials, recognized as intelligent materials with exceptional performance, are extensively employed in flexible grippers. This review aims to provide an overview of flexible robotic grippers and highlight the application of MR materials within them, thereby fostering research and development in this field. This work begins by introducing various common types of flexible grippers, including shape memory alloys (SMAs), pneumatic flexible grippers, and dielectric elastomers, illustrating their distinctive characteristics and application domains. Additionally, it explores the development and prospects of magnetorheological materials, recognizing their significant contributions to the field. Subsequently, MR flexible grippers are categorized into three types: those with viscosity/stiffness variation capabilities, magnetic actuation systems, and adhesion mechanisms. Each category is comprehensively analyzed, specifying its unique features, advantages, and current cutting-edge applications. By undertaking an in-depth examination of diverse flexible robotic gripper types and the characteristics and application scenarios of MR materials, this paper offers a valuable reference for fellow researchers. As a result, it facilitates further advancements in this field and contributes to the provision of efficient gripping solutions for industrial automation. [ABSTRACT FROM AUTHOR]

In this study the optimum topology distribution of the magnetorheological elastomer (MRE) layer in an adaptive sandwich plate is investigated. The adaptive sandwich plate consists of an MR elastomer layer embedded between two thin elastic plates. A finite element model has been first formulated to derive the governing equations of motion. A design optimization methodology incorporating the developed finite element model has been subsequently developed to identify the optimum topology treatment of the MR layer to enhance the vibration control in wide-band frequency range. For this purpose, the dynamic compliance and density of each element are defined as the objective function and design variables in the optimization problem, respectively. The method of the solid isotropic material with penalization (SIMP), is extended for material properties interpolation leading to a new MRE-based penalization (MREP) model. Method of moving asymptotes (MMA) has been subsequently utilized to solve the optimization problem. The developed finite element model and design optimization method are first validated using benchmark problems. The proposed design optimization methodology is then effectively utilized to investigate the optimal topologies of the magnetorheological elastomer (MRE) core layer in MRE-based sandwich plates under various boundary and loading conditions. Results show the effectiveness of the proposed design optimization methodology for topology optimization of MRE-based sandwich panels to mitigate the vibration in wide range of frequencies. [ABSTRACT FROM AUTHOR]

Recently, numerous studies have demonstrated that the physics-informed neural network (PINN) can effectively and accurately resolve hyperelastic finite deformation problems. In this paper, a PINN framework for tackling hyperelastic-magnetic coupling problems is proposed. Since the solution space consists of two-phase domains, two separate networks are constructed to independently predict the solution for each phase region. In addition, a conscious point allocation strategy is incorporated to enhance the prediction precision of the PINN in regions characterized by sharp gradients. With the developed framework, the magnetic fields and deformation fields of magnetorheological elastomers (MREs) are solved under the control of hyperelastic-magnetic coupling equations. Illustrative examples are provided and contrasted with the reference results to validate the predictive accuracy of the proposed framework. Moreover, the advantages of the proposed framework in solving hyperelastic-magnetic coupling problems are validated, particularly in handling small data sets, as well as its ability in swiftly and precisely forecasting magnetostrictive motion. [ABSTRACT FROM AUTHOR]

• A dynamic theory of the HMS curved rod under 3D large deformation is presented. • The "tension-bending" and "shear-torsion" coupling effects of curved rod emerge in our model. • The finite element formulation and exact linearization of the dynamical problem are obtained. • An implementation based on Newmark algorithm and some numerical examples are presented. • Several experiments about a quarter arc HMS robotic arm are presented. Magnetorheological elastomers are active materials which can be actuated by the applied magnetic field. Hard magnetic soft (HMS) materials, a type of magnetorheological elastomers, show great potential in the fields of biomedical engineering and soft robotics, due to their short response time, remote operation, and shape programmability. To exploit its potential, a series of theoretical frameworks of HMS rods have been developed, but they are mainly limited to the static rod models or classical curved rod models that fail to consider the effect of the "initial curvature" on the distribution of the stress. In this work, we develop a curved rod theory to predict the 3D dynamic motion of the rod-like HMS robotics under large deformation. Based on the geometrically exact rod theory, we include the heterogeneous initial length of the longitudinal fiber caused by "initial curvature" into our model and obtain the reduced balance equations of the HMS robotics. As a result, the "tension-bending" and "shear-torsion" coupling effects of curved rods emerge in the present model. A numerical implementation of our model based on the classical Newmark algorithm is presented. To validate our model, three numerical examples, including the dynamic snap-through behavior of a bistable arch, are performed and compared with the simulation or experiment results reported in literatures, which show a good agreement. Finally, we experimentally study the 2D and 3D static and dynamic motion of a quarter arc HMS robotic arm under an applied magnetic field of 10 mT, and our model gives a satisfactory prediction, especially for static deformation. [ABSTRACT FROM AUTHOR]