Squeeze Behaviors of Magnetorheological Fluids under Different Compressive Speeds

Abstract

The compression tests under the unidirection for magnetorheological (MR) fluids have been studied at different compressive speeds. The results indicated that curves of compressive stress under different compression speeds at the applied magnetic field of 0.15 T overlapped well and were shown to be an exponent of about 1 of the initial gap distance in the elastic deformation region and accorded well with the description of continuous media theory. The difference in compressive stress curves increases significantly with an increasing magnetic field. At this time, the continuous media theory description could not be accounted for the effect of compressive speed on the compression of MR fluid, which seems to deviate from the Deborah number prediction under the lower compressive speeds. An explanation based on the two-phase flow due to aggregations of particle chains resulting in much longer relaxation times at a lower compressive speed was proposed to explain this deviation. The results have guiding significance for the theoretical design and process parameter optimization for the squeeze-assisted MR devices such as MR dampers and MR clutches based on the compressive resistance.

Magnetic circuit design for the performance experiment of shear yield stress enhanced by compression of magnetorheological fluids

“…MR fluids are usually considered as Bingham fluids with high viscosity 27 – 29 . It is believed that the normal force F is determined by the magnetic field strength H , the initial gap distance h 0 , and the compressive strain ε with a relation as F ∝ H 2 / h 0 (1 − ε ) 2 14 , 30 – 33 . This means that a higher magnetic flux density, a smaller initial gap distance, or a larger compressive strain corresponds to a larger normal force and compressive stress.…”

Improvement of roughness in ultrasonic assisted magnetorheological finishing of small titanium alloy nuts by orthogonal test method

“…It overcomes the shortcomings of easy pollution, low efficiency and low controllability of traditional electrochemical polishing 17 , 18 , magnetic abrasive finishing 19 , 20 , ultrasonic polishing technology 21 , 22 , and has advantages of high surface quality, low surface damage, high efficiency, low energy consumption, controllable material removal rate, etc. 23 – 25 . It has been successfully used in industrial production for ultra-precision machining of optical surfaces and semiconductor wafers 26 , 27 .…”

Magnetic Characterization of MR Fluid by Means of Neural Networks

“…Consequently, MR fluids can change from a liquid to a solid state under the influence of a magnetic field [15]. MR fluids can tolerate shear stress until a yield stress threshold, strongly depending on the strength of the applied magnetic field and due to the chains' resistance against flow [16,17]. The control of the physical change of the MR fluid from liquid to semi-solid under the application of a magnetic field is useful for active vibration control and brakes [18].…”