Search Results (95)

In rotating machinery, the demands for torque sensor resolution and range in various torque measurements are becoming increasingly stringent. This paper presents a novel variable stiffness torque sensor designed to meet the demands for high resolution or a large range under varying measurement conditions. Unlike traditional strain gauge-based torque sensors, this sensor combines the advantages of torsion springs and magnetorheological fluid (MRF) to achieve dynamic adjustments in both resolution and range. Specifically, the stiffness of the elastic element is adjusted by altering the shear stress of the MRF via an applied magnetic field while simultaneously harnessing the high sensitivity of the torsion spring. The stiffness model is established and validated for accuracy through finite element analysis. A screw modulation-based angle measurement method is proposed for the first time, offering high non-contact angle measurement accuracy and resolving eccentricity issues. The performance of the sensor prototype is evaluated using a self-developed power-closed torque test bench. The experimental results demonstrate that the sensor exhibits excellent linearity, hysteresis, and repeatability while effectively achieving dynamic continuous adjustment of resolution and range. Full article

Magnetorheological fluids (MRFs) and elastomers (MREs) are two types of smart materials that exhibit modifiable rheological properties in response to an applied magnetic field. Although they share a similarity in their magnetorheological response, these two materials differ in their nature, structure, and mechanical behavior when exposed to a magnetic field. They also have distinct application differences due to their specific rheological properties. These fundamental differences therefore influence their properties and applications in various industrial fields. This review provides a synthesis of the distinct characteristics of MRFs and MREs. The differences in their composition, rheological behavior, mechanical properties, and respective applications are summarized and highlighted. This analysis will enable a comprehensive understanding of these differences, thereby allowing for the appropriate selection of the material based on the specific requirements of a given application and fostering the development of new applications utilizing these MR materials. Full article

To effectively suppress spindle vibrations in rotating machinery, magnetorheological (MR) dampers, as an ideal vibration control device, have attracted attention. To enhance the vibration damping effect, in the paper, a MR damper vibration with a multi-layered permanent magnet as the magnetic source is designed, and the self-made magnetorheological fluid is used as the damping medium. The mechanical properties of the MR damper were obtained through testing and calculation. On this base, both simulation and experimental methods are used to demonstrate the effectiveness of the multi-layered permanent-magnet MR damper. The simulation results show that the critical speed increases greatly for the first four modes. The experimental results show that the Y-direction displacement decreases greatly, especially at 1800 rpm and at 3400 rpm, after applying the MR damper. The vibration displacement at 1× frequency shows a 69.74% reduction at 2600 rpm and a 65.69% reduction at 3200 rpm in the Y-direction after applying the MR damper. The effectiveness of the multi-layered permanent magnet MR damper in rotor vibration suppression was confirmed. Full article

Tuned Liquid Dampers (TLDs) are dissipative devices that mitigate vibrations through the out-of-phase movement of a fluid, typically water, inside a container relative to a main structure. Water’s low density and viscosity have led to modifications to enhance their effectiveness. Fluid properties, such as density or viscosity, significantly impact their performance by altering mass and damping, respectively. When magnetorheological fluids are employed, magnetic fields can modify the fluid viscosity, affecting the damping. This study experimentally examines the effect of a magnetic field and ambient parameters on the viscosity of different low-cost, custom-prepared magnetic fluids. A tube filled with magnetic liquids into which diverse non-magnetic spheres are dropped was employed, considering on- and off-states of the magnetic field generated by a pair of Helmholtz coils. The impact on the fluid viscosity variation of different measured variables was statistically analyzed. It was found that in all cases, the variations in ambient temperature and relative humidity had no effect on the results. While the magnetic field had a large effect on the viscosity of the magnetic fluid, for the sunflower oil-based fluids, the spheres used or the concentration of iron filings had a greater effect on the viscosity than the presence of the magnetic field. Full article

Magnetorheological (MR) fluids are frequently reported to have potential as lubricants for hydrodynamic bearings operating at high loads, but no comprehensive effort has been made to investigate their performance under a variety of operating conditions. This paper, therefore, presents an extensive experimental and numerical investigation of an MR-lubricated hydrodynamic journal bearing subjected to different loads and magnetic fields, and compares these results to those of an oil-lubricated bearing. It is shown that by increasing the magnetic field strength, the performance characteristics of the bearing can be changed from low hydrodynamic friction and a high transition speed to high hydrodynamic friction and a low transition speed. Furthermore, it was found that the way in which these characteristics scale with increasing load differs for the MR- and oil-lubricated bearings. With MR lubrication, the relative change in characteristics with the application of a magnetic field is smaller at higher loads, due to the strong shear-thinning rheology of MR fluids. To include these effects in the model, a basic relation for the apparent MR viscosity as a function of shear rate, temperature, and magnetic field strength is introduced. Finally, the bearing was made from a polymer to improve wear resistance under MR lubrication, but a comparison with a Reynolds equation-based numerical model indicates possible performance degradation due to shape errors, which is a known issue with this bearing material. Full article

This paper aims to present a hybrid steering control method combining the self-guidance capability of a wheelset and fuzzy logic controller (FLC), which were applied to our new micro-autonomous railway inspection vehicle, enhancing the vehicle’s stability. The vehicle features intelligent inspection systems and a suspension system with variable damping capability that uses smart magnetorheological fluid to control vertical oscillations. A mathematical model of the steering dynamic system was developed based on the vehicle’s unique structure. Two simulation models of the vehicle were built on Simpack and Simulink to evaluate the lateral dynamic capability of the wheelset, applying Hertzian normal theory and Kalker’s linear theory. The hybrid steering control was designed to adjust the torque differential of the two front-wheel drive motors of the vehicle to keep the vehicle centered on the track during operation. The control simulation results show that this hybrid control system has better performance than an uncontrolled vehicle, effectively keeps the car on the track centerline with deviation below 10% under working conditions, and takes advantage of the natural self-guiding force of the wheelset. In conclusion, the proposed hybrid steering system controller demonstrates stable and efficient operation and meets the working requirements of intelligent track inspection systems installed on vehicles. Full article

Magnetorheological fluids (MRFs) are functional fluids that exhibit rapid and reproducible rheological responses to external magnetic fields. MRFs have been used to develop haptic devices with fine haptic information for teleoperated surgical systems. To achieve this, we developed various compact MRF clutches for haptics and integrated them into a twin-driven MRF actuator (TD-MRA). Several types of TD-MRAs were developed in prior studies. This study used three sets of TD-MRAs to construct a haptic device with a delta-type linkage system that displays a three-dimensional (3D) force vector for users in virtual reality or teleoperation systems. We described the kinematic design of the linkage system based on the torque performance of the TD-MRA and evaluated the output force performance using an open-loop force controller. The haptic interface was designed to achieve greater than 2 N of output forces and a motion range of ±50 mm. Experimental results demonstrated an average error of 0.1 N, indicating that the open-loop controller performed effectively in all directions at the tested platform positions. Full article

In order to mitigate the vibration caused by fluid–structure interaction in water-conveying pipelines, a semi-active control method based on a magnetorheological (MR) damper is proposed. First, the partial differential equation governing the pipeline micro-element, which is simply supported at both ends, is formulated. This equation is then transformed into state-space expressions through non-dimensionalization and the Galerkin method. Based on passive dissipative control theory, a semi-active control law ensuring Lyapunov global asymptotic stability is derived based on the relative motion between the dynamic vibration-absorbing mass and the pipeline. Next, an on–off control algorithm is designed for the MR damper. The results of simulation and hardware-in-loop experiments demonstrate that the semi-active control law can significantly reduce the vibration of the pipeline system. The contribution of this research is to propose a new MR tuned mass damper (MR-TMD) to suppress vibration in water-conveying pipelines. The proposed MR-TMD scheme and its control method provide a theoretical basis and practical reference for the engineering application of semi-active vibration control in water-conveying pipelines. Full article

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. Full article

The radial pulse is a critical health marker with expanding applications in wearable technology. To improve these applications, developing a pulse generator that consistently produces realistic pulses is crucial for validation and training. The goal of this study was to design and test a cost-effective pulse simulator that can accurately replicate a wide range of age-dependent radial pulses with simplicity and precision. To this end, this study incorporated a magneto-rheological (MR) fluid device into a cam-based pulse simulator. The MR device, as a key component, enables pulse shaping without the need for additional cams, substantially reducing the cost and complexity of control compared with existing pulse simulators. To evaluate the performance of the MR pulse simulator, the root-mean-square (RMS) error criterion (less than 5%) was used to compare the experimentally obtained pulse waveform with the in vivo pulse waveform for specific age groups. After demonstrating that the MR simulator could produce three representative in vivo pulses, a parametric study was conducted to show the feasibility of the slope-based pulse-shaping method for the MR pulse simulator to continuously generate a range of age-related pulses. Full article

The aim of this study is to propose a damper based on magnetorheological (MR) fluid and elastomer for application in vehicle engine mounting systems to dissipate the vibration energy transferred from the engine to the vehicle body. The magnetic circuit structure of the damper has been precisely designed, and its reasonableness has been verified by static magnetic field simulation. After the principle prototype’s completion, the damper’s mechanical properties are tested by an electro–hydraulic servo fatigue machine. The results show that with the current increase, the damper’s in-phase stiffness increases by 20.6%. The equivalent damping improves by 81.6%, which indicates that the damper has a good MR effect. A new phenomenological model is proposed, and a genetic algorithm is used to identify the parameters of the model. Finally, a 1/4 vehicle engine vibration damping system model is established and a dynamics simulation is carried out. The simulation results show that the damper effectively reduces the vibration transmitted from the engine to the body, and the vibration-damping effect is even more obvious through sky-hook control. This proves that the damper proposed in this study has good vibration-damping performance. Full article

The magnetorheological brake (MRB) epitomized a revolutionary modification in the braking systems because of its extremely efficient and well-controlled performance. To increase the safety and controllability of automotive braking system, researchers have developed a different MRB structures. Although much research on magnetorheological brakes has shown positive results in terms of brake torque, braking time, thermal efficiency, etc., the ability to increase braking force by expanding the disc surface, through which the magnetic field operates in a compact structure, is restricted. To address this issue, a new multipole MRB configuration with a unique pole head design that maintains compactness. Initially, the conceptual design was achieved by leveraging the combined impact of the twin disc-type structure and multipole concept. The model was used in a dynamic simulation to show how the braking torque of a magnetorheological braking system varies with coil current. The effects of circular sector pole head shape on braking performance were investigated using COMSOL Multiphysics software (version 5.5). A three-dimensional electromagnetic model of the proposed MRB was developed to examine the magnetic flux intensity and the impact of magnetic field dispersion on the proposed pole head structure of a magnetorheological brake. Based on simulation results, the circular sector pole head configuration is capable of increasing the active chaining regions for the MR fluid on the rotor surface, allowing for a more effective use of magnetic flux throughout the whole surface of a rotating brake disc, thereby increasing the magnetic field usage rate. The acquired simulation results show an increase in braking torque while keeping a compact and practical design structure. Full article

The aim of this study is to design and manufacture a multi-plate clutch system that uses magnetorheological (MR) fluid control to allow for a variable power transmission ratio in power distribution systems. MR fluid is a smart material that enables presenting a solution to the shocks and power loss that occur due to mechanical problems in power distribution systems. As such, the longitudinal and lateral dynamic properties of 4WD (four-wheel drive) vehicles were examined and analyzed to develop an algorithm to control the front/rear power distribution according to the road surface state and driving conditions. To verify the algorithm, the CarSim vehicle dynamics simulation program was adopted to perform experiments to understand the vehicle’s dynamic performance improvements and turning stability via a HILS (Hardware in the Loop) system. In this study, an MR fluid, multi-plate clutch was used that combines a dry clutch and a wet clutch using the characteristics of the MR fluid. Such a clutch was designed to enable continuous and smooth torque transmission by utilizing the strengths of each of the dry and wet clutches. The CarSim vehicle dynamics program was used to conduct the experiments, which were conducted by linking to the manufactured MR fluid clutch experimental device. The experiments investigated the dynamic performance based on the power distribution ratio by performing longitudinal flat, inclined driving and lateral DLC (double lane change) driving. In summary, this study found that it is possible to perform power transmission by applying a current to an MR fluid and forming a magnetic field to change the flow properties of the fluid to control the torque transmission ratio that occurs in an MR fluid clutch. Full article

Magnetorheological and electrorheological fluids manifest a change in rheological behavior when subjected to a magnetic or electric field, respectively, such that they require electrical and magnetic characterization. In this paper, a simple and accurate mathematical model based on a small number of parameters provides the relative magnetic permeability of magnetorheological fluids as a function of the applied magnetic field. Furthermore, for the testing and magnetic characterization of magnetorheological fluids, a new metering equipment setup is implemented. Starting with the achieved experimental data, the mathematical relation ${\mu }_r=f\left(B\right)$ is represented by means of a radial basis function neural network, with neurons having a Gaussian activation function; by means of post-training pruning procedures, the trained neural network is applied using the proposed data. Therefore, the obtained mathematical relation ${\mu }_r=f\left(B\right)$ is in good agreement with the experimental data, with an approximate error of 8%. Full article

Damping involves the various frictional and other obstructive effects that attenuate free vibration. For a long time, people have mainly used it to make various dampers to reduce mechanical vibration and consume kinetic energy. It is widely used in fields such as aerospace, automotive, and consumer electronics. These dampers mainly act on mechanical structures. In recent years, with the rapid development of novel human–machine interaction methods and force/tactile feedback technology, the damper has begun to act on people, such as when a person interacts with a robot and their force is applied to a structure with damping. This type of damper requires variable damping, and the amount of variation is controlled by the magnitude of human action. This study used magnetorheological fluid (MRF) instead of traditional damping fluids, such as silicone oil, sesame oil, and mechanical oil. Magnetorheological fluid is a controllable fluid with magnetorheological effects, and its viscosity (hardness) can be changed by changing the nearby magnetic field. This study took the design of variable damping keyboard buttons with haptic feedback as an example to study the electromagnetic and dynamic models of variable dampers based on magnetorheological fluids. The experimental setup was designed and used to verify the haptic effectiveness of the scheme, which can be applied to the development of other haptic dampers that require variable damping. Full article