The aim of this work is to investigate the effect of the small magnetorheological fluid gap on the braking performance of the magnetorheological brake. In this article, theoretical analyses of the output torque are given first, and then the operating principle and design details of the magnetorheological brake whose magnetorheological fluid gap can be altered are presented and discussed. Next, the magnetic circuit of the proposed magnetorheological brake is conducted and further followed by a magnetostatic simulation of the magnetorheological brakes with different sizes of fluid gap. A prototype of the magnetorheological brake is fabricated and a series of tests are carried out to evaluate the braking performance and torque stability, as well as the verification of the simulation results. Experimental results show that the braking torque increases with the increase in the current, and the difference for the impact of the fluid gap on braking performance is huge under different currents. The rules, which the experimental results show, have an important significance on both the improvement of structure design for magnetorheological brake and the investigation of the wear property under different fluid gaps.

In this article, thermal characteristics and tribological properties of a disk-type magnetorheological fluid–based brake are investigated under various brake operating conditions such as different working gaps. In order to achieve this goal, a theoretical analysis of the heating and heat dissipation of the magnetorheological brake is first performed and then the transient temperature behaviors of the magnetorheological brake are investigated through simulation works associated with the finite element method. Subsequently, an experimental apparatus is established to measure temperature distributions of the magnetorheological brake as a function of the operating time. Thereafter, several heating and wear tests are conducted on the magnetorheological brake, and worn surfaces of the friction plates are observed using a scanning electron microscope to understand tribological characteristics of the magnetorheological brake. It is shown that the smaller working gap causes the higher temperature compared with the larger gap under the same magnitude of the input current applied to the magnetorheological fluid domain. This thermal behavior consequently results in the reduction of the braking torque. It is also demonstrated from the wear test that the small working gap significantly affects both wear and tribological characteristics showing the large ridges and deep grooves on the worn surfaces of the friction plate.

In this paper, the effect of the surface textures of braking disc on the braking performance is experimentally investigated under the conditions of different working gaps and applied currents. For this purpose, a new configuration of magnetorheological fluid brake (MRB) with adjustable working gap is developed to improve the manufacturing accuracy and cost, and to reduce the problem of replacing the braking disc. In addition, the braking discs with three types of surface texture are designed and machined. Based on the test bed developed for the proposed MRB, a series of experiments are carried out on the manufactured prototype and the results are presented to obtain the relationship among the surface texture of the braking disc, applied current, working gap and the braking performance. The results show that the braking torque is significantly influenced by the working gap and surface texture of the braking disc, and the maximum braking torque is obtained on the conditions of 0.25 mm working gap and the braking disc with square surface texture.

A new test method of reciprocating magnetorheological polishing was presented and designed, and the mechanism of the micro-removal and the characteristics of the reciprocating magnetorheological polishing were analyzed. According to the reciprocating magnetorheological polishing experimental setup, the preparation process and proportion of the magnetorheological polishing fluid were studied. On the basis of analyzing the composition and characteristics of each component, the working parameters of the prepared magnetorheological polishing fluid were tested. With magnetorheological polishing fluid it prepared and reciprocating magnetorheological polishing method, the magnetorheological polishing experiments of borosilicate glass (K9) were carried out. The results show the effectiveness of the prepared magnetorheological polishing fluid and the practicability of the reciprocating magnetorheological polishing method.

No abstract