Ice Impact Protection for Thin Skin Composite Laminates

A major limitation to the use of advanced composite materials is the inherent weakness of the laminates in the through-thickness direction. The V-22's susceptibility to ice damage is another example of this problem. The current post-buckled design provides the needed lightweight construction but is not sufficient to withstand the impact of the ice shards. Unfortunately, the V-22 is weight critical and beefing up the skin may not be an adequate response as this would cascade through the design. We are proposing to apply technology developed using Navy SBIR funding to demonstrate that a solution to this problem is readily attainable with minimum impact on either the weight or cost of the V-22. Our technology z-fiber reinforcement, has been shown to increase fracture toughness up to 20x in carbon-epoxy, with vitually no adverse impact on in-plane properties, or on current fabrication/tooling approaches applicable to the V-22. Additionally, the z-fiber process has demonstrated a 50% reduction in delamination area in previous hail impact work conducted with Boeing. In Phase I, we will fabricate representative test panels which we will impact with ice shards to quantify the reduction in damage size for a given level of impact. In Phase II additional material property data (fatigue, ETW, etc.) will be developed and a demonstration V-22 stiffened component will be selected and fabricated.