Papers by Keyword: Magnetorheological Fluid (MRF)

Abstract: Magnetorheological fluid is a kind of new intelligent materials, because of its good controllable and mechanical properties; therefore it can be widely used in aerospace, mechanical engineering and automotive engineering, precision processing engineering, control engineering and engineering field. This paper introduces magnetorheological fluid mechanics model of MRF, temperature static shear yield stress, and the influence of MRF static shear yield stress test, introduces magnetorheological fluid in the application of variable hardness collar. The application tendency of the magnetic fluid flow is pointed out

Abstract: In our earlier work, test equipment has been designed, simulated and fabricated to perform experiment on MR fluids in squeeze mode. Preliminary results were gathered and presented for the purpose of validating the test equipment. Therefore, in this paper, a further systematic investigation of MR fluids in squeeze mode has been carried out. As a result, MR fluids experienced rheological changes in three stages during compression and tension. Fluid-particles separation phenomenon was the main caused for the unique behaviour of MR fluids. Particle chains depended on the structure transformation in which the carrier fluid movement can be controlled by changing the magnetic field strength.

Abstract: A magnetorheological digital flow control valve is designed using magnetorheological fluid (MRF) magnetorheological characteristics. The paper gives the magnetorheological digital flow control valve’s structure and mathematical model, and according to the working condition, proposes using the pulse width modulation (PWM) control mode which is one of the digital valve control modes to realize the flow control. Simulation analysis has been done and the results show that the magnetorheological digital flow control valve has good static performance, high frequency switching speed and response，easy to realize intelligent control.

Abstract: In mechanical equipments or manufacturing processes, force control is definitely required to achieve desired performance or to ensure product quality. Aiming at this issue, this paper introduced an author-invented torque servo device that utilizes magnetorheological fluids (MRF) to provide a controllable torque. In the paper, the structure and working principle of the MRF-based torque servo device (MRT) were introduced, the constitutive model and the characteristics of the MRF were established and discussed. On the basis, the static and dynamic models of the MRT were both analytically and experimentally studied, and the control of the output torque of the MRT was demonstrated. As an example, the application of the MRT to the polishing of aspheric surfaces was presented in the end.

Abstract: Rheology is an important property of MRF (Magnetorheological fluids) and an important basis for designing a MRF device. For researchers and engineers, therefore, a practical and reliable magnetorheometer is certainly required for the study and application of the MRF and its devices. In this paper, the principle of a novel magnetorheometer was introduced, the structure and the function of major components were explained, the test process for the rheological property of the MRF by using this magnetorheometer was illustrated, the distribution of the electromagnetic field in the gap, where the MRF is filled, was analyzed by means of ANSYS software tools, and experiments were conducted to ascertain the validity of the magnetorheometer.

Abstract: In order to meet the requirements of research on steer-by-wire force feedback, a MRF- damper-based experimental system was developed. In the paper, the necessity of the experimental system was analyzed, the general structure and hardware components were introduced. The design of the rotary MRF dampers was illuminated in detail. Experiments showed that the MRF-damper-based haptic system can be used for the study of automobile steer-by-wire system.

Abstract: Preliminary analysis of magnetorheological fluid usability in fluid lubricated bearings has been described in the present study. Results of the study aimed at rheological properties of chosen fluids, which possess magnetic properties (both ferrofluids and magnetorheological fluids) with respect to their application in slide bearings have been presented Preliminary analysis of potential advantages related with the magnetic fluid bearing construction was carried out. Results of measurements of normal force developed within magnetorheological fluid and ferrofluid in result of magnetic field action at various shear rate values have been presented.

Abstract: Structure and basal application of magnetorheological fluids as well as their application in rotary shaft seals, have been presented in this study. As the application of magnetorheological fluid in seals is relatively purely known, the conducted studies were aimed at defining their operational parameters. The most essential was manner of the MR fluid delivery into oil gap, mostly the applied fluid volume. Not sufficient volume of the MR fluid often results in non-uniform oil gap filling what in turn decreases the seal efficiency. Results of studies on MR fluid-based seal burst pressure, conducted on specially designed testing stand, have been presented. The results comprise three oil gap sizes of d=0,15mm, d=0,3mm and d=0,5mm, for tests conducted with various volume of MR fluid applied on single sealing stage. Comparative values of the seal burst pressures obtained for three oil gap sizes of multi-stage seal, with the same apparent volume of MR fluid (the same fluid and oil gap volume ratio), were also presented.

Abstract: This paper presents a method to simulate the mechanical behavior of magnetorheological fluid (MRF) subjected to magnetic field in the pre-yield region in ANSYS. The main idea is to devide an MRF element into two coincident elements, one of them has density and viscosity without shear modulus while another has shear modulus without density and viscosity. Taking a simply supported MRF sandwich beam as an example, good results and reasonable conclusion are obtained by comparing the results with the theoretical analysis and experimental study of Ref.[1]. The validity of finite element analysis is also investigated in this paper. At present, there is no exactly appropriate element type in ANSYS to model MRF, this kind of method called coincident elements method (CEM) will provide a new way to model the structures with MRF or MR dampers in ANSYS, and it also has reference roles for the future development of related elements in ANSYS.

Abstract: The paper shows the design of an innovative magneto-rheological fluid brake (MRF brake). The integral brake torque from a conventional MRF brake is not quite large since it commonly adopts a single ring-type electromagnetic pole to produce magnetic flux to change the MRF viscosity. This presented innovative MRF brake features with multiple electromagnetic poles to significantly increase the active chaining areas for MRF, and then increase the brake torque. Because of the special arrangements of pole numbers and directions of magnetic flux for these poles, the active chaining areas of MR fluid and brake force are maximized. The simulation results confirmed the feasibility and ability of this innovative MRF brake. Performance comparison shows that the innovative MRF brake has 118% more torque output than a commercial one.