Résumé
We study the homogenization of a linear elastic solid reinforced by a small volume fraction of very stiff fibers. The effective material is characterized by the emergence of concentrations of strain energies around and within the fibers. The former is expressed in terms of the discrepancy appearing between the averaged effective displacements in the fibers and in the matrix, by means of a tensor-valued capacity of the cross-sections of the fibers. The latter corresponds to a combination of stretching, bending and torsional energies, where the torsional contribution is specific to anisotropic constitutive components.