Measurement of fiber orientation angle in FRP by intensity method

As fiber reinforced polymeric composites consist of reinforcements and matrixes, the mechanical characteristics of materials are determined by these two properties. Naturally, the property of composites depends on the property of matrices but fiber length, fiber aspect ratio, fiber content ratio, fiber orientation state of reinforcements directly affect the mechanical characteristics of composites such as tensile strength, fatigue strength, elasticity coefficient, thermal and fracture characteristics. Since the measurement of fiber orientation distribution state within fiber reinforced polymeric composites is very important for deciding the molding conditions of the products or for verifying the dynamic characteristics of molded products, a reliable method of measuring fiber orientation angle distribution should be established firmly. As the measurement of fiber orientation angle is very important, it is correct to measure each fiber orientation angle directly but it is not desirable as a measurement method since it requires lots of efforts. Therefore, researches are required on non-destructive simple measurement method. The fiber orientation angle can be measured precisely as much as the fiber aspect ratio is small when measuring the fiber orientation angle placed on the x–y plane from the result of this study. This method can be applied by image processing the photographs obtained from soft X-ray composites, which was currently used as products.