Unconfined Yield Strength and the Flow of Powders and Granular Material
Powders and granular materials are made up of freely moving particles and air. For powders, the particles are small, ranging in size from nanometers to microns. For granular materials, the particles are typically in the millimeter size range. Because they are made up of freely moving particles and air, powders and granular materials exhibit properties of both solids and liquids. Under certain conditions, they may behave more like liquids and flow easily. Under other conditions, they may behave more like solids and not flow at all or even become solid. In order to understand their behaviour, it is necessary to measure how powders and granular materials behave under different conditions.
