Mukhopadhyay Shomeek, Peixinho Jorge
Chemistry Department, Columbia University, New York, New York 10027, USA.
Phys Rev E Stat Nonlin Soft Matter Phys. 2011 Jul;84(1 Pt 1):011302. doi: 10.1103/PhysRevE.84.011302. Epub 2011 Jul 13.
We present an experimental study of disordered packings of deformable spheres. Fluorescent hydrogel spheres immersed in water together with a tomography technique enabled the imaging of the three-dimensional arrangement. The mechanical behavior of single spheres subjected to compression is first examined. Then the properties of packings of a randomized collection of deformable spheres in a box with a moving lid are tested. The transition to a state where the packing withstands finite stresses before yielding is observed. Starting from random packed states, the power law dependence of the normal force versus packing fraction or strain at different velocities is quantified. Furthermore, a compression-decompression sequence at low velocities resulted in rearrangements of the spheres. At larger packing fractions, a saturation of the mean coordination number took place, indicating the deformation and faceting of the spheres.
我们展示了一项关于可变形球体无序堆积的实验研究。将荧光水凝胶球体与断层扫描技术一起浸入水中，实现了三维排列的成像。首先研究了单个球体在压缩下的力学行为。然后测试了在带有活动盖子的盒子中随机收集的可变形球体堆积的特性。观察到向一种堆积在屈服前能承受有限应力的状态的转变。从随机堆积状态开始，量化了不同速度下法向力与堆积分数或应变的幂律依赖关系。此外，低速下的压缩 - 解压序列导致了球体的重新排列。在较大的堆积分数下，平均配位数出现饱和，表明球体发生了变形和刻面。
