Metrological X-ray computed tomography for fiber geometrical characterization and mechanical properties prediction in fiber-reinforced plastic parts

Injection-molded fiber-reinforced thermoplastic parts are increasingly used in several industrial applications thanks to their low weight, high mechanical properties, vast design possibilities, and reduced costs. However, the geometrical characteristics of fibers (i.e. fiber orientation, length, and concentration) have a considerable impact on the mechanical properties of the fabricated parts. The conventional methods used to study the relationship between the fiber characteristics and the resulting mechanical properties typically rely on destructive and time-consuming techniques. Micro X-ray computed tomography, instead, allows performing non-destructive measurements of the geometrical characteristics of fibers. Nevertheless, tomographic measurements are still affected by a consistent number of influence factors, hindering the results accuracy. This work proposes a methodology to verify and enhance the accuracy of tomographic fiber geometrical measurements as well as to determine their uncertainty. The improved outcomes are then exploited to accurately predict the mechanical properties of injection-molded glass-fiber-reinforced specimens characterized by different fiber volume fractions.