Quantitative Evaluation of Fiber Distribution in Discontinuous CFRP Using Dark-Field Images Derived by X-Ray Talbot-Lau Interferometer

Abstract

This study proposes a new method which quantitatively evaluates distributions of carbon fiber content, mean fiber orientation, and variance of fiber orientation in CFRP. Dark-field images taken by Talbot-Lau interferometer are employed for the method. Talbot-Lau interferometer can measure X-ray scattering generated by carbon fibers in the optical path as a dark-field signal. Dark-field image visualizes the distribution of dark-field signal. The authors first describe a model that relates number of carbon fibers oriented in a certain orientation in CFRP and the dark-field signal. The model is then expanded so that it can calculate dark-field signal of CFRP laminates in which carbon fibers of different orientations are stacked in the thickness direction. Carbon fiber distribution, mean fiber orientation, and variance of fiber orientation in a given CFRP can be evaluated by using the model. The method is validated by comparing the results of the method to the results those are directly measured from the optical microscopic images. The authors believe that the proposed method has a potential to be a new nondestructive inspection method for CFRP.