Ordered packing of elastic wires in a sphere

Department of Physics, Institute for Advanced Studies in Basic Sciences (IASBS), P.O. Box 45195-1159, Zanjan 45137-6673, Iran.
Physical Review E (Impact Factor: 2.29). 04/2012; 85(6). DOI: 10.1103/PhysRevE.85.061108


In this paper we study the ordered packing of wires in a sphere. We propose an analytical model and compare the model predictions with the results of our experiments and simulations for the maximum packing fraction, the number of formed coils, the fractal dimension, and bending energy. We show that the relative system size [i.e., the ratio of the wire radius to the sphere radius (a/R)] is the most important control parameter for the maximum packing fraction. We find that the number of coils obeys a power-law relation of the form N∼(R/a)1.5 and the fractal dimension of the structures is 2.5, independent of the system size. Our theoretical results are in good agreement with the experimental data and the predictions of the numerical simulations.

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    • "Significant progress has recently been made in the understanding of dense packings of elastic and elasto-plastic wires, in absence of thermal fluctuations , inside of rigid three-dimensional confinement [11] [12] [13] [14]. A particular restriction shared by all these studies is the perfect rigidity of the cavities—a constraint rarely met in nature or biomedical applications . "
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    Nature Communications 07/2014; 5:4437. DOI:10.1038/ncomms5437 · 11.47 Impact Factor
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    ABSTRACT: The packing of elastic objects is increasingly studied in the framework of out-of-equilibrium statistical mechanics and thus these appear to be similar to glassy systems. Here, we present a two-dimensional experiment whereby a rod is confined by a parabolic potential. The setup enables spanning a wide range of folded configurations of the rod. Measurements of the distributions of length and curvature in the system reveal the importance of a stacking process whereby many layers of the rod are grouped into branches. The geometrical order of patterns increases with the confinement strength. Measurements of the distributions of energies lead to the definition of an energy scale that is correlated with the elastic energy of the stacked parts of the rod. This scale imposes energy partition in the system and might be relevant to the framework of the thermodynamics of disordered systems. Following these observations, we describe the patterns as excited states of a ground state corresponding to the most ordered geometry. Eventually, we provide evidence that the disordered state of a folded rod becomes spontaneously closer to the ground state as confinement is increased.
    Physical Review E 01/2014; 89(1-1):012407. DOI:10.1103/PhysRevE.89.012407 · 2.29 Impact Factor