Composite Structural Materials.

A resurgence of intense interest, research and applications activity mark the beginning of what may be considered the second generation of filamentary composite materials. Such interest and activity are as well-founded now as they were at the outset of the composite era more than tweny years ago. The possibility of using relatively brittle materials with high modulus, high strength, but low density in composites with good durability and high tolerance to damage and which, when they do fall, do so in a non-catastrophic manner, has been shown feasible, and the full potential is only just beginning to be realized. The promise of substantially improved performance and potentially lower costs provides the driving force behind continued research into fiber reinforced composite materials for application in aerospace hardware. Much progress has been achieved since the initial developments in the mid 1950s. Applications to primary structure have been rather limited on operational vehicles, mainly being utilized in a material-substitution mode on military aircraft. More extensive experiments, as a part of NASAs influential ACEE program, are currently underway on large airplanes in commercial passenger operation and in a few military developments, such as the AV-8B which has seen only limited service use and the X-29 which is undergoing flight tests.