Estimation of fiber orientation distribution in carbon-fiber-reinforced polyamide 6 using X-ray diffraction images

Abstract

The carbon fiber orientation distribution (FOD) of carbon fiber-reinforced polyamide 6 was estimated using wide-angle X-ray diffraction (WAXRD) images of the composites. In the diffraction image of the aligned carbon fibers, the straight line connecting the pair of diffraction spots caused by the graphite crystal is orthogonal to the fiber axis. This property was employed to investigate the FOD. In this study, we attempt to express WAXRD images, that is, the intensity distribution ( ) by the linear combination of the radial basis functions arranged in the diffraction angle ( ) and azimuth angle ( ). Consequently, FOD corresponds to the weight vector derived through serial waveform separation. Based on this concept, we attempted to identify the laminated composition of the composites, such as unidirectional, cross-ply, and quasi-isotropic composites. The analysis results were in good agreement with the ideal laminated composition.