T. Kraft, H. Riedel, M. Moseler

In a Discrete Element Method (DEM) simulation angles of repose are analyzed which reveal static properties of a granular material. The theoretical maximum angle is related to the internal angle of friction of the material, $\phi = \arctan(T/N)$, where $T$ is the maximum shear force the powder bulk can withstand when applying a normal force $N$. Two angles of repose, namely the outflow angle $\theta_{\text{O}}$ obtained by heap decomposition through slow outflow and the heap angle $\theta_{\text{H}}$ obtained by heap composition via pouring grains on top of a newly forming heap are measured. The simulation was carried out using SimPARTIX.

T. Kraft, H. Riedel, M. Moseler

Dry pressing and subsequent sintering in order to shape metallic or ceramic powders is characterized by its high dimensional accuracy. The homogeneous filling of the die prior to compaction is an important prerequisite for maintaining the dimensional accuracy because spatial density variations during compaction can lead to undesirable distortion during the sintering. Discrete Element Method (DEM) simulations allow to model the die filling process in detail and to predict the resulting powder density distribution. Various optimization approaches for a homogeneous density can be analyzed in the simulation. The simulation was carried out using SimPARTIX.

Erosive wear occurs in many processes involving particles which hit a wall with large relative velocities. Even though the material removal for each impact is very small the collective damage is often significant. The video displays the wear in bent pipes which is caused by particle impacts due to gravity. On the left, dry particles enter the pipe. In the center, the particles are surrounded by a fluid with low viscosity and on the right by a fluid with high viscosity. The color coding of the semi-transparent pipes reflects the amount of wear ranging from low (blue) to high (red). The the overall wear decreases with increasing fluid viscosity. The simulation was carried out using SimPARTIX.

C. Dehning, T. Kraft

The possibility of coupling discrete element method (DEM) and finite element analysis (FEA) simulations is particularly attractive in order to model contact between granular matter and soft bodies. The coupling takes place at the surface of a body which is in contact with the granular material. The nodes of the surface mesh are shared by the DEM and the FEA code. The DEM code sends node forces to the FEA software which sends node displacements back in return. The displacement affects the granular material in contact which again causes changes of the node forces. The video shows a bulk of particles falling onto an elastic membrane which is clamped at the edges. The simulation was carried out using SimPARTIX, MpCCI and Abaqus.