Composite Materials for Aeronautic Application

The most important aspects of composite usage in aircraft structures are discussed. Different kinds of fiber reinforcement and matrix are compared. A large part of the article is focused on carbon epoxy prepregs, that is, preimpregnated materials having a continuous fiber reinforcement and an epoxy resin matrix. The major issues of prepreg processing are outlined, with a description of the different phases of the process. Most of the discussion is focused on the lay-up plus autoclave processing, which is the most frequent processing approach. A short comparison between laminate and sandwich structures is also reported. “No prepreg” techniques are also listed, such as resin transfer molding and resin infusion molding. Elements are reported of composite structural properties, including the effect of temperature, aging, and damage tolerance. Some additional information on aging and accelerated aging techniques is also included. The behavior of composites exposed to fire, as well as functional properties (conductivity, acoustic damping, etc.) are also shortly listed. The advantages of lighter structures are considered taking in account also the cost issues, and some specific applications of composites in the aircraft structures are described, stressing the very fast increase of these materials in the aeronautic structural applications. Finally, the future trends in the technological improvement of composite material, processes, and structures for aeronautical application are shortly outlined. Keywords: composite materials; aeronautics; prepregs; carbon fiber; epoxy; aeronautical applications