Impact Resistance of Composite Sandwich Plates

Abstract

The impact resistance of composite sandwich plates has been studied ex perimentally. Several panels with [±45/0] s Hercules AS4/3501-6 graphite/epoxy face- sheets were manufactured with different types of cores: aluminum honeycomb, Nomex honeycomb and Rohacell plastic foam with three different core thicknesses, 3.2 mm, 6.4 mm and 9.6 mm. These panels were impacted at a range of low energy levels (less than 10 joules). X-ray photos were taken to determine the extent of delamination damage, and the panels were sectioned so the location and lengths of delaminations, debonds, and core damage could be determined. Extensive delamination and core damage was found in spec imens with no visible surface damage. Core damage in the Rohacell consisted of cracks in the foam while the damage in the honeycomb consisted of the buckling of cell walls. The largest delaminations were found in the interface between the bottom two plies (-45°/+45°) of the top facesheet.