Condensation of elastic energy in two-dimensional packing of wire

Forced packing of a long metallic wire injected into a two-dimensional cavity leads to crushed structures involving a hierarchical cascade of loops with varying curvature radii. We study the distribution of elastic energy stored in such systems from experiments, and high-resolution digital techniques. It is found that the set where the elastic energy of curvature is concentrated has dimension $D_{\mathcal{S}}=1.0\pm 0.1$, while the set where the mass is distributed, has dimension $D=1.9\pm 0.1$.