A numerical study of the impact properties of sandwich panels with different cores

Sandwich structures based on strong, stiff skins bonded to either side of a low density core material are finding increasing use in aerospace, offshore and marine industries. The skins are designed to resist tensile and compressive stresses and are usually made of aluminium or fibre reinforced polymers. The core is designed to resist shear stresses and is usually made of balsa wood, polymer foams, or expanded metal or polymer honeycombs. Unfortunately, some sandwich structures have very low energy absorption capability when subjected to impulsive loads normal to the sandwich plane. This is of concern due to the susceptibility of sandwich structures to damage caused by foreign object impact. Since the damage behavior of sandwich structures are affected by the mechanical properties of both core and laminated facesheets, the damage behaviors under impact loading deserve careful investigation to ensure the reliability and safety of sandwich structures. The purpose of this paper is to compare the mechanical response of sandwich panels with different cores subjected to impact loading. An approach for modelling sandwich structures in the commercial finite element code LS-DYNA is presented. The core is modelled with solid elements and shell elements are used for the thin facesheets. Sandwich panels with glass fibre-reinforced polymer facesheets were used, combined with two different cores; polystyrene foam and polypropylene honeycomb. A parametric study can be done using the FE model presented in this paper that would provide valuable information to help select appropriate core material for maximum impact resistance.