HYDRO-MECHANICAL CONSTANT-SPEED MOTION CONTROL USING SHEAR THICKENING FLUID

摘要

This paper proposes a novel approach to control the velocity of a piston using dilatant fluid. Commonly, a pressure compensated flow control valve is used for this purpose. It produces excellent results but is mechanically complex. A setup is proposed that makes use of the unique properties of dilatant (i.e. shear thickening) non-Newtonian fluids. A simple tube section filled with dilatant material can be used to achieve very low sensitivity of flow rate vs. pressure difference. A numerical study shows how the power law which relates the fluid shear rate to its viscosity results in this low sensitivity of flow to pressure difference. An experimental setup was build to validate the findings using a cheap and commercially available shear thickening fluid. It was found that the dilatant material used does not have a highly pronounced dilatant property and therefore the sensitivity of flow vs. pressure difference was not as low as desired. Nevertheless, the results support the practical applicability of this novel type of velocity control.