Discontinuous Shear Thickening with Suspensions of Magnetic Particles

Discontinuous shear thickening (DST) is usually found in very concentrated suspensions of solid particles and is characterized by a sudden jump in stress during a ramp of shear rate. We have investigated this transition in suspension of magnetic particles with the idea of monitoring the critical shear rate with the help of a magnetic field. Furthermore, the use of conductive particles allows one to relate the conductivity of the suspension to the setup of a network of contacts between particles during this transition. We shall compare our experimental rheograms to the prediction of the standard model, and we shall show how the instability observed above a critical stress can be related to the inertia of the rotating tool. Last, we shall present results related to applications in the domain of the control of forces with a magnetic field and emphasize the fact that the control of the DST allows to improve the efficiency of the devices by more than order of magnitude.