3-D Fiber Reinforced, Thermally Conductive Rotor Sheaths

Military helicopters rotors contend with rain, ice, sand, and flying debris. To prevent damage to the expensive blade protective sheaths or coatings are applied to the leading edge of the rotor blades. A 3-D woven composite sheath with high thermal conductivity fibers running through the thickness can offer the best qualities of both metal sheaths and elastomer coatings. Infused with an elastomer matrix, it will achieve excellent sand erosion resistance. Based on a 3-D fiber architecture, it will provide excellent resistance to both impact damage and rain erosion. High conductivity graphite fibers running through the thickness of the composite will mimic the thermal conductivity of the metal sheaths. In this Phase I effort, 3TEX and its partner CCM-UD will produce a 3-D fiber architecture composite rotor sheath prototype. 3TEX will design a 3-D woven preform that incorporates several functions, including impact resistance, local stiffening, and through thickness thermal conductivity. CCM-UD will infuse the preform using VARTM infusion techniques that can include local tailoring of the resin for impact or strength or high temperature. Prototype sheaths will demonstrate the production processes while material coupon testing will determine rain erosion, sand erosion, and impact resistance, as well as thermal conductivity.BENEFITS: Composite rotor sheathes based on 3-D fiber architecture should offer the best performance attributes of both elastomer coatings and metal sheathes. While maintaining the anti-icing functionality of metal sheaths, the 3-D composite rotor sheathes will provide longer component life. The longer component life should not come at a high component cost. The 3-D fiber performing process is sufficiently economical to compete in the E-glass boat hull market, while the VARTM infusion processes reduce tooling costs and speed the part production, so the part prices themselves should be competitive with existing sheaths. However, increasing the time between replacement of the sheaths immediately translates to reduced maintenance costs and higher helicopter readiness levels for the Navy. The payload and range of Vertical Take-off and Landing (VTOL) aircraft, such as helicopters, are highly sensitive to aircraft weight. The 3-D composite rotor sheathes will weigh significantly less than the current metal sheathes. Thus, this new technology sheath will increase the range and payload of every fleet helicopter currently using metal sheaths, such as the V-22. The proposed effort then will offer reduced maintenance costs and increased VTOL range and payload.