Magnetorheological (MR) materials are classified as smart materials due to their responsiveness to external magnetic stimuli. Intensive research on MR materials has led to broad applications in several potential fields. A solid carrier matrix state called MR elastomer with its exceptional magnetic responsive feature is obtained by merging magnetizable particles within an elastomeric polymer. This integration results in outstanding characteristics on the rheological performances. Special prominence is given to the understanding of the base materials and fabrication as well as the functional behavior through various characterization methods. Broad applications of MREs are also explored to provide a profound market picture and to motivate researchers to develop novel technology. The functional behavior of MREs is briefly explained. The art of the materials provides the current position and mapping of the matrix and filler particles. Types of matrix and particles are mentioned together with the level of the research interest on MREs. Description of the fabrication is provided in simple diagrams as summarized from previous works to enhance the MREs performance. The possible tests to reveal the characteristics of the MREs are delivered with the global experimental setup. The review also explains the applications of MREs as well as discussion on the MREs future promising applications.

Recent Progress on Magnetorheological Solids: Materials, Fabrication, Testing, and Applications†

A hydraulic control system for controlling at least one load (1; 30, 40), the respective load pressure as a load-sensing signal via a respective load-sensing line (LS - that as a means for influencing a load-sensing signal, a compensator (10) is present, a corrected load sensing signal (LS - that the compensator (10) consists of a compensation valve (11) and a shut-off valve (12), - that the compensation valve (11) comprises a pressure applied to it load-sensing pressure (p - that the shut-off valve (12) shuts the compensator (10) when at the compensation valve (11) pending load-sensing pressure (p

A hydraulic control system

Optimization of performance of Combined Solar Collector-Geothermal Heat Pump Systems to supply thermal load needed for heating greenhouses

Recent research and applications of ground source heat pump integrated with thermal energy storage systems: A review

Influence of composition of carbonyl iron particles on dynamic mechanical properties of magnetorheological elastomers

In the hydrostatic thrust bearing with open-loop quantity oil supply system for the heavy NC machine tool, the time-variable oil viscosity and the loads will cause the lubricant film thickness deviating from the optimum value, which reduce the bearing film rigidity and affect the machine tool precision. This paper proposed a controllable hydrostatic thrust bearing, which combined the constant flow chambers and the controllable flow chambers. The chamber flow can be adjusted automatically according to the load, the cutting force, and the thermal results of thrust bearing. The controllable chamber flow was adjusted by the electro-hydraulic servo variable mechanism. The oil film thickness error was measured in real time to maintain the most optimum film thickness. The models of controllable chamber flow and servo variable mechanism were established, and the model identification experiments for servo variable mechanism were carried on. The hardware-in-loop simulation results show that the controllable bearings assure the stability and rapidity of system, compensate effectively the effect of load parameter on oil film thickness, and improve the position tracking performance, and validate the creditability of the identification model.

Hardware-in-the-loop simulation on controllable hydrostatic thrust bearing

The low speed performance is the most important indicators of the continuous rotary electro-hydraulic servo motor. The factors which influence the low speed performance consist of nonlinear characteristics such as structural pulsation, friction and leakage characteristic, oil distributing technique, pressure pulsation, servo valve's distinguish ability and so on. In order to improve the low speed performance, the key technique of servo motor was studied. It is analyzed that velocity pulsation and torque pulsation was eliminated in the structure, the structure of blade and oil distributing plate was optimized for improving leakage and oil distributing characteristic, and friction torque was compensated in order to reducing the pulsation. These results can resolve the basic technique problem of the low speed performance and lay foundation for studying electro-hydraulic servo motor.

Research on the key technique of continuous rotary electro-hydraulic servo motor

Because there is flexible load in electro-hydraulic force servo control system, and there is second-order differential section whose oscillation frequency is low in the numerator of the transfer function, the frequency range of the electro-hydraulic force servo control system is influenced badly and the system may oscillate easily even is instability. Aiming at this characteristic of electro-hydraulic force servo control system and the characteristic of the system whose open loop gain is small; the fuzzy control theory is applied to electro-hydraulic force servo control system this typical nonlinear system in order to improve the performance of the system. The models of the system with the fuzzy control theory and without it are built and the simulation and experiment study is done. Comparing the control result of the controller with the fuzzy control theory to the control result of the controller with the traditional PID, and from the results of simulation and experiment, we can find that the controller with the fuzzy control theory can not only increase the frequency range of system, but also improve the precision of system, and the controller can quicken the response ability of the system obviously.

Study of electro-hydraulic force servo control system based on fuzzy control

A simulation research concerning the gap flow performance of multi-pad hydrostatic thrust bearing having circular cavities in the large-scale vertical CNC lathe was described. The Finite Volume Method of Fluent has been used to compute fluid three-dimensional velocity field and pressure field of gap flow between the revolution working table and bearing pad. This study theoretically analyzes the influence of cavity area on the bearing performance according to computational fluid dynamics and lubricating theory. It has revealed its flow distribution law. The simulation results indicate that an improved characteristic can be gotten from a circular cavity multi-pad hydrostatic thrust bearing, oil cavity pressure increases by gradually with cavity area enhancing, pressure reaches extremely large value in some location, decreases gradually by degrees, the effect of cavity area on the velocity is very small . Through this method, the safety of a hydrostatic thrust bearing can be forecasted, and the optimal design of such products can be achieved.

Simulation Research on Gap Flow of Circular Cavity Multi-pad Hydrostatic Thrust Bearing

A hybrid fuzzy control scheme was applied to improve the rigidity of hydrostatic thrust bearing. The bearing oil film control was realized by coupling oil film thickness of four controllable chambers. The chamber flow can be regulated by electro hydraulic servo valve-control variable pump according to the surface roughness, load, cutting force, and thermal effects of worktable. The nonlinear hybrid controller developed was composed of a classical PID controller and a fuzzy controller based on self-adjusting modifying factor, and feed-forward compensation was added. A fuzzy switching mode was employed to avoid the undesirable disturbances caused by the switchover between the two control methods. By simulations and experiments on an electro-hydraulic servo test bench the feasibility of the control scheme was validated by comparison with a PID and a conventional fuzzy control. The research results show that the hybrid fuzzy controller exhibit good dynamic and steady quality, eliminate oil film lubrication failure and be broadly applied in high precision heavy machine tool.

Junpeng Shao

Papers

Hardware-in-the-loop simulation on controllable hydrostatic thrust bearing

Research on the key technique of continuous rotary electro-hydraulic servo motor

Study of electro-hydraulic force servo control system based on fuzzy control

Simulation Research on Gap Flow of Circular Cavity Multi-pad Hydrostatic Thrust Bearing

Control Method of Heavy Hydrostatic Thrust Bearing