Using X-ray tomography, we experimentally investigate the structural evolution of packings composed of 3D-printed hexapod particles, each formed by three mutually orthogonal spherocylinders, during tap-induced compaction. We identify two distinct structural compaction mechanisms: an initial stage dominated by enhanced particle interlocking, which yields local mechanically stable structures through strong geometric entanglement, and a later stage characterized by the formation of dense polytetrahedral aggregates and a sharp increase in the number of five-ring motifs. The emergence of these five-fold symmetric structures indicates that, despite their highly concave geometry, hexapod packings can be effectively treated as hard-sphere-like systems and exhibit similar glass-like disordered configurations. The frustration between local mechanically stable structures and global glassy order suggests a universal organizational principle underlying the structure of uniform and isotropic disordered granular materials.
@article{arxiv.2511.00856,
title = {Competition between Glassy Five-Fold Structures and Locally Dense Packing Structures Governs Two-Stage Compaction of Granular Hexapods},
author = {Rudan Luo and Houfei Yuan and Yi Xing and Yeqiang Huang and Jiahao Liu and Wei Huang and Haiyang Lu and Zhuan Ge and Yonglun Jiang and Chengjie Xia and Zhikun Zeng and Yujie Wang},
journal= {arXiv preprint arXiv:2511.00856},
year = {2025}
}