ABSTRACT Relationships between shear stress and shear strain rate of granular solids have been studied by using a Jenike shear cell. The measurement results show that granular solids obeys Newton`s friction law at low shear rate and obeys Coulomb`s friction law at higher shear rates. Based on the laws of Newton`s and Coulomb`s friction, a plastic-viscous type of constituent relation is built, and a plastic-viscous model has been developed based on the constituent relation and the Mohr-Coulomb law. Comparisons on velocity profiles inside a conical hopper and a cylindrical bunker have been made with measurement results for 15 kinds of granular solids, which have wide ranges of the angle of internal friction between about 20 to 60° and of the angle of wall friction between about 5 to 30°. The results show that the plastic-viscous model predicts well the velocity profiles. Predictions on the velocity profiles have been made from Jenike`s co-axility theory. The results show that Jenike`s co-axility theory gives reasonably good predictions for the powders with angles of wall friction from 7.6 to 13.6°, but gives unsatisfactory predictions for the powders with angles of wall friction below 6.5° and above 25°.
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