Characteristics of a magnetorheological fluid in high shear rate

The information on the properties of the magnetorheological fluid (MRF) in high shear rate, in particular a shear rate greater than 10 000 s−1, is important for the design of devices utilizing the MRF with very narrow fluid gaps, which are used in high-speed applications. However, very little research has been conducted on this subject. The objective of this study is to provide such information. MRF-140CG (Lord Corp.) is chosen as an example MRF. The plastic viscosity, thermal sensitivity, and durability of the fluid, especially under a shear rate greater than 10 000 s−1, are reported. The plastic viscosity is almost constant under a wide range of magnetic input. In contrast, MRF-140CG is sensitive to the shear rate; its sensitivity is relatively low at high shear rates. The thermal sensitivity shows negative values, and the effect of temperature decreases with increasing magnetic input. According to the result of the duration test at 30 000 s−1 and at a temperature of 120 °C, the lifetime dissipation energy is 5.48 MJ ml−1.