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Composite materials used today are at the leading edge of material technology, with performance and cost appropriate to demanding applications such as aerospace, marine, automobiles etc. Composite materials outperform metals in terms of specific strength and specific stiffness. In addition to superior structural properties, composites are in many cases better in corrosion resistance, fatigue resistance, thermal insulation, thermal and electrical conductivity, and acoustic insulation than metals. Aerospace structures for example require high specific stiffness and strength and a very high degree of dimensional stability under a wide range of temperatures, which are encountered in space. Because of a negative coefficient of thermal expansion of the carbon fibers along their axis, aerospace structures can be designed such that a zero-dimensional change is achieved over a wide range of temperatures. These unique properties make the composites an obvious choice for both military and civilian aircraft components. Military aircraft being more concerned with performance than cost has witnessed the maximum utilization of advanced composites. Fiber-reinforced polymer composites are being used extensively in the primary and secondary structures and control surfaces of military aircraft. Common components include wing skins and substructures, rudders, flaps, vertical and horizontal stabilizers, radome, rotors and blades and various access doors. Reinforcement fibers are mostly carbon and graphite, but glass, aramid, and hybrids are also used [Chawla, 08; Jamal, 09].