Analysis of the in-plane fiber orientation distribution in carbon fiber composites using wide-angle X-ray diffraction

Abstract

The orientation of discontinuous carbon fibers (CF) in carbon fiber reinforced plastic (CFRP) influences the various properties, such as mechanical, thermal, and electrical properties. Here, we propose a fast and nondestructive method for evaluating the in-plane orientation distribution of CFs in CFRPs using wide-angle X-ray diffraction (WAXD). A symmetric transmission method was adopted as the specimen configuration to reduce the influence of the CFRP plate thickness on the WAXD measurement. The orientation distribution function was expressed as the sum of several Gaussian functions to analyze the orientation distribution of the uniaxially oriented and randomly oriented CFRP plates. The measurement of this method was accurate when the orientation distribution was wide. Because this method utilizes diffraction from the crystal structure in CFs, it is applicable to CFRPs where the diffraction from the matrix polymer in the azimuthal direction can be corrected with a linear baseline.