Department of Mechanical Engineering, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan.
J Phys Condens Matter. 2010 Aug 18;22(32):324102. doi: 10.1088/0953-8984/22/32/324102. Epub 2010 Jul 15.
Ultrasonic propagation velocity in a magnetic fluid (MF) and magnetorheological fluid (MRF) changes with the application of an external magnetic field. The formation of clustering structures inside the MF and MRF clearly has an influence on the ultrasonic propagation velocity. Therefore, we propose a qualitative analysis of these structures by measuring properties of ultrasonic propagation. Since MF and MRF are opaque, non-contact inspection using the ultrasonic technique can be very useful for analyzing the inner structures of MF and MRF. In this study, we measured ultrasonic propagation velocity in a hydrocarbon-based MF and MRF precisely. Based on these results, the clustering structures of these fluids are analyzed experimentally in terms of elapsed time dependence and the effect of external magnetic field strength. The results reveal hysteresis and anisotropy in the ultrasonic propagation velocity. We also discuss differences of ultrasonic propagation velocity between MF and MRF.
在磁场中的磁流变液（MRF）中，超声波的传播速度随外加磁场的变化而变化。MRF 内部的团聚结构的形成对超声波的传播速度有明显的影响。因此，我们通过测量超声波传播特性来对这些结构进行定性分析。由于 MRF 是不透明的，因此使用超声波技术进行非接触检测对于分析 MRF 的内部结构非常有用。在这项研究中，我们精确地测量了基于碳氢化合物的 MRF 的超声波传播速度。基于这些结果，从时间依赖性和外加磁场强度的影响两个方面，对这些流体的团聚结构进行了实验分析。结果表明超声波传播速度存在滞后和各向异性。我们还讨论了 MRF 和 MRF 之间的超声波传播速度的差异。
