(111b) Powder Flow Testing with Biaxial and Triaxial Devices

The flow behaviour of cohesive powders is examined with the discrete element method (DEM), a tool that allows to consider the details of the contact-friction and -adhesion forces for each particle contact and to solve the dynamical evolution for all particles in the system. An advanced contact model for fine powder particles (size around one micrometer) will be introduced, as based on experimental results obtained via the particle interaction apparatus, a modified atomic force microscope.

Given the contact law, the dynamic behaviour of cohesive powder flow can be ?microscopically? modelled, investigated and understood in depth. The results of steady-state flow, anisotropy evolution, incipient yielding and consolidation will be presented. Dynamic formation of the shear zone is examined in a bi-axial and tri-axial box setup. Evolution of waves in these systems will also be discussed.