Two-dimensional densely ordered packings of non-convex bending and assembled rods

The investigation of the problem of particle packing has provided basic insights into the structure, symmetry, and physical properties of condensed matter. Dense packings of non-spherical particles have many applications, both in research and industry. We report the two-dimensional dense packing patterns of bending and assembled rods, which are non-convexly deformed from simple objects and modeled as entangled particles. Monte Carlo simulations and further analytical constructions are carried out to explore possible densely packed structures. Two typical densely packed structures of C-bending rods are found, and their packing densities are identified as being functions of the aspect ratio and central angle. Six shapes of assembled rods, representing the combined deformations of rods, are employed in simulations with the packing structures classified into three types. The dense packing density of each packing pattern is derived as a function of different shape parameters. In contrast with the case of disordered packings, both the shape and order are verified to affect the packing density. (C) 2019 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.