Pugnaloni Luis A, Sánchez Iván, Gago Paula A, Damas José, Zuriguel Iker, Maza Diego
Instituto de Física de Líquidos y Sistemas Biológicos (CONICET La Plata, UNLP), cc. 565, 1900 La Plata, Argentina.
Phys Rev E Stat Nonlin Soft Matter Phys. 2010 Nov;82(5 Pt 1):050301. doi: 10.1103/PhysRevE.82.050301. Epub 2010 Nov 4.
We analyze, experimentally and numerically, the steady states, obtained by tapping, of a two-dimensional granular layer. Contrary to the usual assumption, we show that the reversible (steady state branch) of the density-acceleration curve is nonmonotonous. Accordingly, steady states with the same mean volume can be reached by tapping the system with very different intensities. Simulations of dissipative frictional disks show that equal volume steady states have different values of the force moment tensor. Additionally, we find that steady states of equal stress can be obtained by changing the duration of the taps; however, these states present distinct mean volumes. These results confirm previous speculations that the volume and the force moment tensor are both needed to describe univocally equilibrium states in static granular assemblies.
我们通过实验和数值分析了二维颗粒层在敲击作用下所获得的稳态。与通常的假设相反，我们表明密度 - 加速度曲线的可逆部分（稳态分支）是非单调的。因此，通过以非常不同的强度敲击系统，可以达到具有相同平均体积的稳态。耗散摩擦盘的模拟表明，等体积稳态具有不同的力矩张量值。此外，我们发现通过改变敲击持续时间可以获得等应力的稳态；然而，这些状态具有不同的平均体积。这些结果证实了先前的推测，即体积和力矩张量对于唯一地描述静态颗粒集合体中的平衡状态都是必需的。
