Lightweight Integrally Stiffened Composite Structure

Sandwich construction has excellent stiffness and strength to weight, and therefore has been used in many airframe applications for fixed and rotary wing aircraft. Unfortunately, honeycomb sandwich structures have proven costly to maintain due to limited durability. Perhaps the largest single limitation has been corrosion. The Navy operates its aircraft on the open seas in one of the harshest aircraft environments known. In addition to direct salt spray exposure, the maritime carrier aircraft environment features exposure to sustained high levels of humidity and occasional hot gas exposure. Non-metallic core such as HRH-10 Nomex or HRH-36 Kevlar/Korex do not corrode directly, however they remain susceptible to other failure modes such as impact and subsequent moisture damage. In the Phase II effort, Aurora Flight Sciences proposes to design and fabricate a complex curvature fairing using stretch-broken carbon fiber (SBCF) and demonstrate the ability of this material to produce an aircraft quality component without honeycomb that reduces weight and/or overall manufacturing and lifecycle costs. Results of the Phase I effort showed that SBCF integrally stiffened panels can be more weight efficient when compared to traditional honeycomb sandwich panels. The success of the Phase I effort in demonstrating the concept feasibility has paved the way for the design and fabrication of a full-scale article during the Phase II program.