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.

The video shows the simulation of a tensile test. The tensile specimen is shown in a half-section. The color scheme represents the plastic strain occurring during the strain. The end of the videos shows a stress-strain diagramm of the simulation in comparison with the experiment.

The video shows a thoothbrush filament moving through a numerical model of a toothpaste enriched with abrasive particles. At the bottom of the simulation domain, an idealistic model of enamel is implemented. It was studied how the abrasive particles interact with the toothpaste fluid and the toothbrush filament. The influence of the abrasive character of the toothpaste can be studied by the induced stresses into the surface of the enamal.

Spray drying is a process used to transform fine primary powder into larger granules which provide better characteristics (e.g. flowability, pressability etc.). Our simulations focus on the evolution of the microstructure of the individual granules. Hence, the video shows an individual drop consisting of particles (spheres) and a liquid (only its surface is displayed). During the drying, the liquid surface recedes due to evaporation and causes the particles to form a spherical structure. Varying parameters such as surface tension, particle cohesion, friction and size distribution allows to study their impact on the final shape and structure of the granule.

The sequence shows an impacting body on a ductile target made of Al6061-T1. The impacting body is assumed to be ideally hard. The impact velocity is $45 \mathrm{m/s}$ and is tilted $51^°$ from the horizontal axis. The spacing of the SPH particles is $50\mu \mathrm{m}$. The depth of the crater is compared to the experimental results by Takaffoli & Papini (2012).

This video shows the drying of a silver ink micro droplet on a solid substrates. The simulation is carried out using the discrete element method (DEM) which is combined with an analytic solution of the fluid motion via one-way-coupling. For visualization of the patterns of solid sediment after drying, only the solid content of the nano-suspension (i.e. the silver particles) is shown. This method can be used e.g. to determine the optimum solid content for a given drop size and a desired sediment pattern (i.e. ring shaped vs fully covered).

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.

The video of the simulation shows a thoothbrush filament moving through a numerical model of a toothpaste enriched with abrasive particles. At the bottom of the simulation domain, an idealistic model of enamel is implemented. It was studied how the abrasive particles interact with the toothpaste fluid and the toothbrush filament. The influence of the abrasive character of the toothpaste can be studied by the induced stresses (colored in red) into the surface of the generic enamal. For a clearer identification of the induced stresses, the fluid is shown in a half-section.

C. Dehning, T. Kraft

The movie shows a fluid in a rigid pipe which is connected to a hose of rubber-like material. A piston moves downward through the pipe thereby pushing the fluid into the hose which is sealed by a disc at the lower end. The hose bulges due to the increasing pressure until, finally, buckling into a state of lower energy occurs. The direction of the buckling is purely statistical.

This a euronews futuris feature from March 25, 2014. euronews knowledge brings you a fresh mix of the world's most interesting know-hows, directly from space and sci-tech experts.

Discrete Element Method (DEM) simulations can be used to model the traction of a tire on a granular ground. The DEM force laws can be parameterized in order to represent various types of grounds ranging from sand over mud to snow. In the video a strong cohesion is used to make the particles very sticky. A constant torque is applied on the tire which is initially at rest. The particles are color coded according to their velocity magnitude ranging from blue (zero velocity) to red (highest velocity). First, the tire accelerates. But then, the tire comes to rest again. The sticky granular material is compacted by the tire motion which causes a torque slowing down the rotation. Some granular material remains in the groves of the tire profile. The simulation was carried out using SimPARTIX.

C. Dehning, T. Kraft

The movie shows lamellas of different flexibility which are used to sweep cohesive granular matter by a lateral movement. The effectivity of the sweeping depends strongly on the rigidity of the lamella. Cleaning processes are applications for this simulation model.