Proportionality between powder cohesion and unconfined yield strength from shear cell testing

From an analysis of the geometry of the yield locus and the Mohr's circle for determining unconfined yield strength (fc) in shear cell testing, it has been shown that powder cohesion is proportional to fc, where the proportionality constant is a function of angle of linearized yield locus, (1-sinθ)/(2cosθ). While both parameters are routinely included in shear cell data, only one parameter is needed to characterize flow properties of a new powder.