In horizontally shaken granular material different types of pattern formation have been reported. We want to deal with the convection instability which has been observed in experiments and which recently has been investigated numerically. Using two dimensional molecular dynamics we show that the convection pattern depends crucially on the inelastic properties of the material. The concept of res...

The knowledge about granular materials is rather limited compared to the respective information on the solids, while a unified theory encompassing all granular material phenomena has not been created yet [1]. Despite the fact that granular material is the discontinuous media its behavior is commonly described by the continuum approach. Consequently, the definition of stresses in granular materi...

The effect of the force chain network on sound propagation in a granular material is poorly understood. To quantitatively study these effects, we perform acoustics experiments in a two dimensional photoelastic granular material in which force chains are visible. We send acoustic pulses into the material from a point source and measure the effects of this pulse via two methods: accelerometers wi...

By mixing glass beads with a curable polymer we create a well-defined cohesive granular medium, held together by solidified, and hence elastic, capillary bridges. This material has a geometry similar to a wet packing of beads, but with an additional control over the elasticity of the bonds holding the particles together. We show that its mechanical response can be varied over several orders of ...

The mechanical response of a wet granular layer to imposed shear is studied experimentally at low applied normal stress. The granular material is immersed in water and the shear is applied by sliding a plate resting on the upper surface of the layer. We monitor simultaneously the horizontal and the vertical displacements of the plate to submicron accuracy with millisecond time resolution. The r...

Pore scale modeling plays a key role in fluid flow through porous media and associated macroscale constitutive relationships. The polyhedral shape and effective local pore size within granular material microstructure are computed in this study by means of the Euclidean Distance Transform (EDT), a local maxima search (non-maximum suppression), and a segmentation process. Various synthetic packed...

A model for granular material is presented that describes both the internal deformation of each granule and the interactions between grains. The model, which is based on the FLIP-Material Point, particle-in-cell method, solves continuum constitutive models for each grain. Interactions between grains are calculated with a contact algorithm that forbids interpenetration, but allows separation and...

Landslides are one of the main natural threats for both people and infrastructure in mountainousregions. In most cases, landslides are triggered by the loss of cohesion in a soil due to the increasingwater saturation level after long or intense rainfalls. Only little is known on the triggering of failuresat the microscopic scale due to the limited experimental accessibility and ...

Landslides are one of the main natural threats for both people and infrastructure in mountainousregions. In most cases, landslides are triggered by the loss of cohesion in a soil due to the increasingliquid saturation level after long or intense rainfalls. Only little is known on the triggering of failuresat the microscopic scale due to the limited experimental accessibility and the...

We study experimentally the fracture mechanisms of a model cohesive granular medium consisting of glass beads held together by solidified polymer bridges. The elastic response of this material can be controlled by changing the cross-linking of the polymer phase, for example. Here we show that its fracture toughness can be tuned over an order of magnitude by adjusting the stiffness and size of t...