FRP is a composite material of glass fiber and its products (glass cloth, belt, felt, yarn, etc.) as reinforcing materials and synthetic resin as matrix material. Fiber reinforced composites are made up of reinforced fibres and substrates. The diameter of fiber (or whisker) is very small, generally under 10μm, the defect is less and smaller, the fracture strain is about 30 per thousand or less, it is brittle material, easy to damage, fracture and be corroded. The matrix is much lower in strength and modulus than in fiber, but it can withstand large strains, often with viscoelastic and elastic plasticity, and is a ductile material.