This paper collects some characteristic aspects of the general model-building
framework of the mechanics of complex bodies, that are bodies in which the
material substructure influences prominently the gross behavior through
interactions conjugated with substructural changes. The emphasis in on issues
that are foundational in nature: the geometrica description of the material
elements, their energetic characterization, the representation of interactions,
conditions for the existence of ground states in conservative setting.Comment: 20 pages, in print on "Quaderni di Matematica