Extremely dense granular packings are needed for high resistance concrete or hard ceramics. They can only be realised when the size distribution of grains is strongly polydisperse. Typically power law distributions give the best results. We present a simple packing model for polydisperse...

The propagation of a crack in an isotropic elastic medium is treated as a moving boundary problem. Linear stability analysis shows that for the stretched membrane with a central, initially circular hole all modes are stable. On the other hand all modes are unstable for a two-dimensional...

We describe the contact network of granular packings by a frustrated lattice gas that contains steric frustration as esential ingredient. Two transitions are identified, a spin glass transition at the onset of Reynolds dilatancy and at lower densities a percolation transition. We describe the...

The flow of granular material, like sand, presents many intriguing effects in particular when it is shaken, poured or sheared. Here, the granular medium is modelled by a packing of elastic spheres and simulated via molecular dynamics. Dissipation of energy and shear friction at collisions are...

We perform careful experiments in a turnable cell to determine the angle of repose and various other angles of dry granular materials. We study the dependence of the angle on the presence of walls and find an exponential decay on the distance between the walls. Modification of the granular...

We present a simple one-dimensional model to describe the evolution of a transverse dune field. The model is characterized by the distances between the dunes and their heights, which determine the inter-dune sand flux. The model reproduces the observation that the dunes in a given field have...