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arXiv 2108.09616cond-mat.soft
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三维可变形颗粒阻塞堆积的结构、振动与力学性质

The structural, vibrational, and mechanical properties of jammed packings of deformable particles in three dimensions

Dong Wang, John D. Treado, Arman Boromand, Blake Norwick, Michael P. Murrell, Mark D. Shattuck, Corey S. O'Hern

AI总结:

该研究探究三维可变形颗粒阻塞堆积的特性,发现弯曲能的有无会显著影响振动模式、等静压性及剪切模量与压强的标度关系,强调了颗粒形变和形状变化对软材料建模的重要性。

摘要:

我们研究了具有形状自由度的三维(3D)可变形颗粒阻塞堆积的结构、振动与力学性质。每个三维可变形颗粒被建模为表面三角剖分的多面体,其顶点为球形,顶点位置由形状能量函数确定,该函数包含约束颗粒表面积、体积和曲率的项,并防止颗粒间重叠。我们发现,不含弯曲能的可变形颗粒阻塞堆积存在低频四次振动模式,其数量随非球形度的增加而减少,且与相对于等静压值的缺失接触数相匹配。相比之下,具有非零弯曲能的可变形颗粒的三维阻塞堆积是等静压的,不存在四次模式。我们发现,对于弯曲能为零的颗粒,形状自由度对动力学矩阵本征模的贡献在整个频率和形状参数范围内均很显著。我们进一步表明,系综平均剪切模量$\u27e8 G \u27e9$与压强$P$满足标度关系$\u27e8 G \u27e9 \sim P^β$,其中弯曲能为零的可变形颗粒阻塞堆积的$β\approx 0.75$。相比之下,具有非零弯曲能的可变形颗粒堆积的$β\approx 0.5$,这与形状固定的软球形颗粒阻塞堆积的数值一致。这些研究强调了在模拟阻塞软材料性质时纳入颗粒可变形性和形状变化的重要性。

英文摘要:

We investigate the structural, vibrational, and mechanical properties of jammed packings of deformable particles with shape degrees of freedom in three dimensions (3D). Each 3D deformable particle is modeled as a surface-triangulated polyhedron, with spherical vertices whose positions are determined by a shape-energy function with terms that constrain the particle surface area, volume, and curvature, and prevent interparticle overlap. We show that jammed packings of deformable particles without bending energy possess low-frequency, quartic vibrational modes, whose number decreases with increasing asphericity and matches the number of missing contacts relative to the isostatic value. In contrast, jammed packings of deformable particles with non-zero bending energy are isostatic in 3D, with no quartic modes. We find that the contributions to the eigenmodes of the dynamical matrix from the shape degrees of freedom are significant over the full range of frequency and shape parameters for particles with zero bending energy. We further show that the ensemble-averaged shear modulus $\langle G \rangle$ scales with pressure $P$ as $\langle G \rangle \sim P^β$, with $β\approx 0.75$ for jammed packings of deformable particles with zero bending energy. In contrast, $β\approx 0.5$ for packings of deformable particles with non-zero bending energy, which matches the value for jammed packings of soft, spherical particles with fixed shape. These studies underscore the importance of incorporating particle deformability and shape change when modeling the properties of jammed soft materials.

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