Effect of pendular liquid bridges on the flow behavior of wet powders

Yield loci of wet glass bead powders in the pendular state were measured at different consolidation stresses, solid mass fractions and binder viscosities. A semi-empirical model was developed to describe the relationship between the liquid bridge adhesion forces and the yield loci. It is demonstrated that the slope angle of the linearized yield locus does not vary with the consolidation stress nor with the binder viscosity within the ranges investigated. Modeled and measured yield loci are in good agreement if the first principal stress plane is assumed to enclose an angle of 45° with the plane of the acting preshear stress.