Metallic sandwich structures with hollow spheres foam core

Sandwich structures and foamed materials are typical architectured materials. Their combination provides potentially very performant solutions combining stiffness, strength, energy absorption and acoustic damping. The present contribution deals with the integration of a special type of foams, namely hollow spheres stackings, into sandwich structures.Stainless steel hollow spheres main advantage relies on their smooth stress-strain curves and their very good repeatability, compared to other closed cell metallic foams. Therefore these foams are interesting alone but also in sandwich design.A parametric study of the macroscopic behaviour of random stainless steel hollow spheres packing in uniaxial compression was carried out. Scaling laws for the Young’s modulus, and for yield strength were established, and they are used to calculate sandwich properties.Then one of the studied metallic hollow spheres packing has been integrated in a sandwich structure with stainless steel faces. Four point bending tests have been performed on various sandwich structures with four core thicknesses and three face thicknesses up to large deflection. We obtained thus the stiffness, the critical load where first damage occurs, the maximum load as a function of the sandwich parameters (core and face thickness). We compared this to classical analytical models.