Three Point Bending Tests of Ergal-CFRP Laminates Sandwich Beams monitored by Acoustic Emission

The diffusion of sandwich material in aeronautical and land-transportation fields as structural material has progressively grown during the last 20 years. The largely diffused approach to design sandwich material is based on a proper combination of two different material: one, that typically is a very-low-weight material, constitute the core of the sandwich, the other is applied as sandwich face and it is typically based on high stiffness and strength material. The main function of the core material is related to the final geometry of the component in terms architecture and shape, and from the structural point of view it has the capability to resist to shear stresses. On the other hand the main function of the face material is the surface finishing, in particular the surface roughness and wear behavior, and form the structural point of view it has to resist to membrane stresses (both tensile and bending loads). Different solutions and material combination are presented in literature to obtain low weight and high performance sandwich structure. For example, a metallic foam core is generally combined with a metal face sheet; a composite face is usually coupled with a polymeric foam core or a resin-impregnated paper honeycomb. Such solution are typically used in aerospace, naval and energy production field. Nevertheless, during last 10 years, the basic idea of sandwich structure has been gradually extended to other materials combinations. One of new interesting and growing materials combinations is based on a monolithic metallic bulk material with moderate density and quite high strength as sandwich core, and on a composite laminates with a very low density and a very high stiffness and strength as a sandwich face material [1]. Nowadays few and non systematic data about mechanical behavior of such composite sandwich are available. The aim of this work is to investigate and characterize sandwich beam which core is made by aluminum alloy (Ergal) and face made by Gr-Epoxy composite laminate.