Slotted-Plate Device To Measure the Yield Stress of Suspensions: Finite Element Analysis

A slotted-plate technique has been used to measure the yield stress of suspensions. The wall slip effect is eliminated by opening a number of slots on the plate, which is dragged through the suspension at a constant speed. The yield stress is obtained by determining the point deviating from linearity on the force versus time curve. The suspension filling the slots is assumed to move with the plate. Shearing with the bulk suspension occurs at the slot edges. The preyielding stress evolution is investigated using a finite element method. Stress−strain instead of stress−shear rate material models are used. Both solid and slotted plates are simulated. At the yielding point, the stress is uniformly distributed along the solid-plate surface or along the slot edge, supporting the assumptions put forward toward the yield stress determinations. That is to say, this technique is suitable for yield stress measurements.