Pressure-Wave Propagation in Magnetorheological Fluid

Magnetorheological (MR) fluids are categorized as smart fluids, which are made of small iron particles suspended in carrier fluids such as silicone oil. The presence of a magnetic field will instantaneously increase the viscosity of the MR fluid, which is known as the MR effect. To expand the practical application of the MR fluid, it is very useful to study the pressure wave propagation under high-loading conditions in detail. Therefore, in this study, the behavior of the pressure wave propagating in MR fluid that was generated by the collision between an ultra-high speed projectile and MR fluid was investigated. The impact test was carried out using a vertical gas gun. Three underwater impact sensors were used to measure the pressure wave, and the history of pressure at each point was acquired. From the experimental result, it was found that the compressibility of MR fluid affected the magnitude of peak pressure generated by the entry of an ultra-high speed projectile into the MR fluid. Furthermore, it was confirmed that the yield shear stress and the increase in shear stress due to the magnetic field greatly affect the damping of the impact-induced pressure.