On the yield stress in magnetorheological fluids: A direct comparison between 3D simulations and experiments

Undoubtedly, the yield stress is the most relevant rheological property of a magnetorheological (MR) fluid. However, available analytical and simulation methodologies to compute the magnetostatic interparticle interactions that govern the yield stress, fail at large particle concentrations and large strain levels. In this communication we propose a 3D finite element methodology (FEM), to compute the yield stress, that grounds on a reduced magnetic field formulation and periodic boundary conditions. This approach takes into account multibody and multipolar interactions and satisfactorily simulates large concentrations and strains. Experiments are also carried out in a torsional magnetorheometer for a wide range of MR formulations. Experimental results obtained are in very good agreement with FEM simulations.