Nondestructive characterization of fiber orientation in short fiber reinforced polymer composites with X-ray vector radiography

Short glass and carbon fiber reinforced polymer composites are used in many industrial fields such as in automotive and consumers industry. Their physical and mechanical properties are often superior to those of unfilled polymer components. One aspect being of utmost importance for these properties is the fiber orientation distribution. Here, we present X-ray vector radiography as a method to characterize fiber orientation in short fiber reinforced polymer components. The method is based on X-ray grating interferometry and takes advantage of X-ray scattering caused by the sample's microstructure. Therefore, micro-structural properties can be probed nondestructively without the need for high spatial resolution. Compared to standard X-ray imaging techniques, currently applied for fiber orientation studies, the presented method does not restrict the size of the sample under investigation and allows for much shorter measurement times. In contrast to existing methods, Xray vector radiography allows the characterization of carbon fiber reinforced polymers despite the weak attenuation contrast between the fibers and the polymer matrix. As this method is also extendable into three dimensions it is a very attractive tool for complex component geometries and carries potential to be applied to materials other than short fiber reinforced polymers.