Mechanical Evaluation of High-Performance Composite Materials and Influences of Environment

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High-performance advanced composite materials are one of the attractive and promising materials for future technological areas, where high strength and high stiffness as well as good fatigue properties combined with low specific gravity are required. In this investigation, the influence of water, electron radiation, ultra-violet radiation, and vacuum on polymer matrix composites including epoxy and PEEK matrix reinforced with carbon fibers and aramid fibers, as well as metals reinforced with SiC whisker and continuous alumina fiber. The polymer matrix composites are highly influenced by electron radiation through hardening of matrix and increased fiber/matrix interfacial strength, in particular, loaded transverse to fibers. The mechanical properties of aramid fiber reinforced epoxy matrix composites are also influenced by vacuum environment : the tensile and fatigue strengths are decreased by vacuum, because it decreased fiber strength. Atomic force microscopy shows nanoscopic fiber damage induced by vacuum, which promoted fiber splitting, resulting in lower strength and elastic modulus. The investigation of low-velocity impact on various kinds of epoxy and PEEK matrix reinforced with carbon and aramid fibers. Investigations are also extended to influence of vacuum and high temperature on metal matrix composites under uniaxial and tension/torsion combined loading, and fracture mechanisms are discussed.