Comparison of damage resistance of minimum gage aluminum and composite skins

This paper evaluates the relative damage resistance of thin gage aluminum and graphite/epoxy composite skins in a skin/stringer structure typical of rotorcraft skins. The damage of interest here is the result of low velocity impacts and tool drops. Several comparisons are made in this paper. The first comparison is between equivalent areal weight aluminum and composite skins. Additionally, comparisons are made between toughened and untoughened epoxy, and unidirectional tape and woven fabric composites. Comparisons between the aluminum and composite skins reveal that the composite exhibits less visible damage at low impact energies. As expected, toughened resin systems are found to be more damage resistant than untoughened systems and fabrics are more damage resistant than tape skin laminates.