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中国物理学会期刊

振动驱动下双分散硬球颗粒堆积的结构

CSTR: 32037.14.aps.74.20250232

Structures of binary hard-sphere packing under tapping

CSTR: 32037.14.aps.74.20250232
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  • 颗粒物质的堆积行为及其力学性质对工程应用至关重要. 尽管单分散球体堆积研究较为成熟, 但实际体系普遍存在粒径多分散性. 双分散系统作为多分散体系的简化模型, 其粒径与成分比的调控机制尚未完全阐明, 尤其在摩擦效应和制备历史影响方面缺乏系统性分析, 且三维实验数据匮乏. 本研究通过振动实验结合X射线断层扫描技术, 系统研究了双分散硬球体系的堆积特性, 重点探究粒径分布和振动强度对体积分数及微观结构的调控规律. 实验发现, 随振动强度增大, 体系稳态体积分数逐渐降低, 不同成分比体系均呈现类似趋势; 动力学弛豫时间随振动强度呈指数衰减, 且与粒径分布无关; Voronoi元胞分析表明双分散体系中各组分局部体积分布与单分散体系高度相似, 降低振动强度可提升体系密度并减小体积涨落. 此外, 接触数与体积分数的关系遵循单分散体系规律, 且受振动强度和颗粒摩擦特性共同调控. 本研究揭示了多分散颗粒体系堆积行为的普适性特征, 为建立颗粒物质统计理论和发展工程应用提供了关键实验依据, 特别在摩擦效应与动力学协同机制方面取得重要突破.

     

    The packing behavior and mechanical properties of granular materials play a critical role in various engineering applications, including materials handling, construction, and energy storage. Although significant progress has been made in understanding the packing of monodisperse spheres, real-world granular systems often exhibit polydispersity, where particles of different sizes coexist. Binary systems, where the particle size ratio is adjustable, serve as a simplified model to study the structural and dynamical properties of granular materials. However, most theoretical studies on binary systems focus on idealized frictionless models, neglecting the coupled effects of friction and preparation history, and experimental data for three-dimensional systems remain limited. This study seeks to address these gaps by investigating the packing behavior of binary hard spheres under tapping through using advanced experimental techniques such as X-ray computed tomography (CT) and tap-driven compaction. The effects of particle size ratio and tap intensity on the packing fraction and local structure of binary granular systems are investigated systematically. The experimental results show that the steady-state packing fraction decreases as tap intensity increases, exhibiting similar behavior at different composition ratios. Additionally, the compaction dynamics are quantified using the Kohlrausch-Williams-Watts (KWW) relaxation function, revealing that the relaxation time decays exponentially with tap intensity increasing, independent of the composition ratio. Voronoi cell analysis demonstrates that the local volume distribution of each component in a bidisperse system composed of big particles and small particles is highly similar to that in a monodisperse system. Notably, as tap intensity decreases, the system density increases, and volume fluctuation decreases, reflecting the trends observed in monodisperse packings. Furthermore, the study highlights the influence of friction on the packing structure. For binary systems, big particles, with rougher surfaces, pack more loosely than smaller particles, and the coordination number increases with the proportion of smaller particles increasing. This suggests that frictional interactions between particles play a significant role in determining the packing density and structural stability of granular materials. The average coordination number and the steady-state packing fraction are found to be weakly dependent on each other, with friction and tap intensity (or effective temperature) being the primary factors affecting the system’s structural characteristics. These findings provide a comprehensive experimental framework for understanding the packing behavior of binary granular systems, with important implications for material design in industrial applications. This study contributes to developing a more complete statistical mechanical theory for granular materials through combining both frictional effects and the influence of preparation history. Future research may extend these findings to more complex particle size distributions and explore the relationship between structural property and mechanical property.

     

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