Dresden 2009 – scientific programme
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DY: Fachverband Dynamik und Statistische Physik
DY 18: Granular matter / contact dynamics
DY 18.2: Talk
Wednesday, March 25, 2009, 16:30–16:45, HÜL 386
Trigger of failure in granular assemblies — •Philipp Welker1 and Sean McNamara2 — 1Institut für Computerphysik, Universität Stuttgart, 70569 Stuttgart, Germany — 2GMCM, Institut de Physique de Rennes, Université de Rennes I, 35042 Rennes cedex, France
We investigate the mechanisms that trigger the collapse of assemblies of polydisperse granular media subjected to an increasing deviatoric stress. The DEM simulations in two dimensions are evaluated by use of the stiffness matrix.
It is always possible to identify a contact status change that triggers the collapse of the packing. This contact status change almost always causes, in small assemblies, a mechanical instability, or a motion with neutral stability. In a few cases, the status change provokes an oscillation, and a second status change following shortly thereafter introduces an instability. This is when failure happens, and the kinetic energy rises exponentially. In larger assemblies, motions with neutral stability become less frequent, while vibrations frequently appear.
We will explain the different trigger mechanisms and show how they depend on system size. Furthermore, we investigate the sources of energy that drive failure.