Study of the rheological behaviour of monomodal quartz particle beds under stress. A model for the shear yield functions of powders

► Yield locus of a power is described with only two parameters: cohesion and coefficient of friction. ► Model works right with monomodal quartz particle beds. ► Cohesion increases by sixth power of bed compactness and inverse of the particle size. ► Coefficient of friction increases asymptotically with bed compactness depending on particle size.