Brodu Nicolas, Dijksman Joshua A, Behringer Robert P
1] Department of Physics, Duke University, Physics Building, Science Drive, Box 90305, Durham, North Carolina 27708, USA [2] Institut National de Recherche en Informatique et en Automatique, Bordeaux Sud-Ouest, 200 avenue de la Vieille Tour, 33405 Talence, France.
1] Department of Physics, Duke University, Physics Building, Science Drive, Box 90305, Durham, North Carolina 27708, USA [2] Laboratory of Physical Chemistry and Colloid Science, Wageningen University, PO Box 8038, 6700EK Wageningen, The Netherlands.
Nat Commun. 2015 Mar 5;6:6361. doi: 10.1038/ncomms7361.
If you walk on sand, it supports your weight. How do the disordered forces between particles in sand organize, to keep you from sinking? This simple question is surprisingly difficult to answer experimentally: measuring forces in three dimensions, between deeply buried grains, is challenging. Here we describe experiments in which we have succeeded in measuring forces inside a granular packing subject to controlled deformations. We connect the measured micro-scale forces to the macro-scale packing force response with an averaging, mean field calculation. This calculation explains how the combination of packing structure and contact deformations produce the observed nontrivial mechanical response of the packing, revealing a surprising microscopic particle deformation enhancement mechanism.
如果你在沙滩上行走，沙子会支撑你的体重。那么沙子中颗粒间的无序力是如何组织起来，使你不会下沉的呢？这个简单的问题在实验中却出奇地难以回答：测量深埋颗粒之间三维空间的力颇具挑战性。在此，我们描述了一些实验，在这些实验中，我们成功地测量了在可控变形下颗粒填充物内部的力。我们通过平均场计算将测量到的微观尺度的力与宏观尺度的填充物力响应联系起来。该计算解释了填充物结构和接触变形的组合如何产生填充物所观察到的非平凡力学响应，揭示了一种惊人的微观颗粒变形增强机制。
