Ice Impact Protection for Thin Skin Composite Laminates

The primary structural requirement of V-22 fuselage panels is to retain integrity in a post-buckled state under panel compression and shear loads. However, during certain flight conditions, these panels are subjected to impact by high velocity ice shards (300 to 500 knots) shed from the rotor blades. The current panel design of E-glass fabric laminates has shown severe loss in integrity after ice-impact. This proposed program will use sound analytical methods to evaluate alternate material and structural concepts. These methods will reduce the cost of extensive experimentation with different concepts. Impact induced delaminations are critical for composite panels. To enhance the interlaminar fracture toughness and reduce the delamination damage, approaches using toughened matrix materials, adhesive layers, and metal/composite hybrids, will be evaluated. A family of 3-D woven composites recently developed at MSC, which may provide significant improvement in delamination resistance, will also be evaluated. In addition, hybrid composites including a surface layer such as tough films or fabrics to provide extra energy absorption and surface protection, will also be considered. These material concepts will be evaluated by using analytical models for impact damage assessment and panel performance. Promising panel concepts will be fabricated for impact and residual compression strength testing.