“…. Their very rich behavior allows for instance to regularize and thus to study precisely the parts of materials where the deformation tends to concentrate, [56], [32] (inter-phases, [41], [24], [34], [51], porous media, [50], fractures, [2], [3], damage and plasticity, [57], [48]). However the second gradient properties are scarcely measured directly, [9], [10], [35] nor rigorously interpreted from a microscopic point of view.…”