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Merry Christmas and a Happy New Year from the Department for Geodynamics and Sedimentology

After a scientifically very successful year the executive of the Department for Geodynamics and Sedimentology wishes all our members, students and collaborators peaceful and joyous holiday season and a prosperous New Year.

Click here to start movie
(animated gif; 4.6 MB)


About our Season’s Greeting Movie:
Distinct Element Method (DEM) model of the deformation of a granular material (particles have contact Young’s modulus of 1 GPa and a contact friction coefficient of 1.0) under axial shortening (up to 50%) under constant lateral confinement (10 MPa). This high-resolution image of Santa was achieved by tiling results of a small model (<3,500 particles) deformed using distortional periodic space. A better insight into the deformation of Santa can be obtained by plotting passive marker layers, as done in the image and associated movie below. The actual model is highlighted by a red rectangle.

Click image to start movie (animated gif; 4.6 MB)


Several important conclusions can be drawn from this model: First, localisation in the form of shear bands emerges and is hence an inherent property of granular materials (not a boundary effect, because no boundaries exist in periodic space). It is worthwhile noting though that the spacing of the shear bands simply reflects the size of the periodic domain. Second, the lateral strain rate increases dramatically after the onset of localisation due to dilatancy. Third, only one direction of shear bands develops (left dipping) although in theory a conjugate set would be expected. However, the volume outside of the shear bands also deforms (in the form of reverse drag) which accommodates the displacement due to localised deformation by flexure.

The model was designed by Martin Schöpfer and run using the PFC2D software.



Department for Geodynamics and Sedimentology
University of Vienna

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