Regensburg 2016 – wissenschaftliches Programm
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DY: Fachverband Dynamik und Statistische Physik
DY 3: Granular Matter
DY 3.11: Vortrag
Montag, 7. März 2016, 12:30–12:45, H46
Why Mikado is one of the easier granular problems — Cyprian Lewandowski1, Pascal Wieland2, Max Neudecker3, Claus Heussinger2, and •Matthias Schröter3,4 — 1Imperial College, London, UK — 2Georg-August University of Göttingen, Germany — 3MPI for Dynamics and Self-Organization, Göttingen, Germany — 4Friedrich Alexander Universität, Erlangen, Germany
The mechanical stability of a granular packing depends on the number of contacts Z between its particles. For most particle shapes, predicting Z as a function of the average volume fraction φ is complicated by the spatial correlations between simultaneously contacting particles. However, in the dilute packings formed by cylinders with large aspect ratios α (length of the cylinder divided by its diameter) the individual contacts can be expected to become uncorrelated. Philipse (Langmuir 12, 1127 (1996)) derived from this idea the Random Contact Model (RCM) which predicts ZRCM = 2 α φ. Using X-ray tomography of packings of frictional spaghetti and simulations of frictionless spherocylinders we measure how Z depends on α and φ. We find that a non-zero friction coefficient µ increases the range of φ where mechanically stable packings exist, but the average Z value seems to be not influenced by µ. For α in the range 15 to 80 the measured Z is smaller or equal to 0.85ZRCM. We show that this difference can be explained by the way the RCM defines contacts.