Direct Yield Stress Measurement with the Vane Method

In the vane method for measuring the yield stress, the conventional analysis assumes that the stress is uniformly distributed on a cylindrical sheared surface to calculate the yield stress from the maximum torque and vane dimensions. By using two simple procedures, the present work shows that this assumption is justified at the moment of yielding. The yield stress calculated using the proposed methods compares favorably with that obtained with the conventional procedure. A comparison with the yield stress independently determined by other methods again confirms the usefulness of the vane technique as a simple but accurate method for direct yield stress measurement.