Characterization and Formability Analysis of a Composite Sandwich Metal-Polymer Material

In recent years, extensive research was carried out on the development at lightweight materials, combining metals with polymers, so-called composite sandwich metal/polymer materials, in order to face the safety and environmental requirements. These materials are composed by metal sheet skins with reduced thickness and a polymer core. However, the combination of steel with other materials poses new challenges, due to their new or different behavior and non-homogeneity of deformation, needing also a different approach to material characterization and formability analysis. This contribution presents the issues concerning material characterization and behavior for this kind of materials in addition to using and proposing appropriate approaches for traditional testing methodology. Fundamental mechanical characterization is obtained by using, not only the uniaxial tensile test, but including also hydraulic bulge test. Formability characterization for this hybrid material includes hole expansion tests and deep drawing Erichsen test, being also discussed the adequacy and differences between homogeneous and composite material results. Numerical simulations were performed to study the influence of tool geometry during the hole expansion test. For the HET to be adequate for both of types of materials, heterogeneous hybrid material and homogenous metal sheets, the increase of the die or punch radius dimensions demonstrated to be the best option to get the material formability behavior without compromising the adequacy of selected tests.