Constitutive equation for the compression of metallic hollow spheres foam

The mechanical behavior of metallic hollow spheres foam is less prone to strain localization than other metallic foams. Compression loading response is reproductible up to densification making these materials interesting as core material in sandwiches and profiles. To perform an optimization procedure in a structure (such as a sandwich), a macroscopic phenomenological model for the mechanical behavior model is set up. It describes the overall behaviour as the result of the coexistence of several phases describing damage progression into the material : a healthy phase, a damaged phase, and a densified phase. The model gives a description of an equivalent homogeneous material without loosing informations on irreversible mechanisms in the mesostructure. In-situ tomography experiments provide proofs for the existence of theses three phases and allow to investigate their evolution with strain.