The alveolar metal structures allow to introduce in the industrial field the extraordinary characteristics typical of many natural configurations (as the bones structure); for some years now they have been a topic of research of great importance, both scientific and industrial. These are cellular materials consisting of a metal matrix in which, in a suitable foaming process, a multitude of empty volumes of irregular spheroidal geometries and of variable dimensions are set. Such a morphology - foam precisely - guarantees some peculiar properties providing to the material a relatively low density and a extraordinary specific stiffness (ratio between stiffness and weight), great potential for energy absorption, a notable damping effect of vibrations, acoustic insulation and flame resistance.
These characteristics make metal foams a promising solution for any use in the automotive field. For example, when used as filler materials for empty structures or as an interface material between two thin sheets (sandwich panel), they offer great stiffness correlated to a very low weight. Moreover, their use for deformation energy absorption allows the development of really effective active and passive safety devices, based on the ability of these materials to undergo large deformations at relatively constant stresses.