Average particle magnetization as an experimental scaling parameter for the yield stress of dilute magnetorheological fluids

Abstract

We propose an experimental parameter for the scaling of the yield stress (τy) of magnetorheological (MR) fluids: the average particle magnetization ⟨Mp⟩ as estimated from magnetization curves of the MR suspensions. When τy was expressed as a function of this scaling parameter, the curves for MR suspensions prepared with particles of different saturation magnetization and even different morphology collapsed together. In addition, the collapse worked reasonably well for a wide range of magnetic fields: from weak fields below which the sensitivity of our magnetorheometer could not detect the τy, to fields close to particle saturation. The collapse failed for particles of highly anisotropic morphology, which must be indicative of non-magnetostatic contributions to the yield stress.