Micro-CT investigation on fatigue damage evolution in short fibre reinforced polymers

The development of predictive models for fatigue behavior of materials is closely related to a quantitative assessment of damage nucleation and propagation phenomena. Conventional methods used for this purpose, such as microscope observations, conventional radiographs, ultrasonography techniques, either are destructive or do not reach an adequate resolution. Imaging techniques using synchrotron radiation, and in particular X-ray micro-computed tomography (micro-CT), however, combine the advantages of a nondestructive technique with a high spatial resolution. In this paper, damage evolution in samples extracted from PA6.6GF35 specimens subjected to fatigue tests interrupted at different stages of fatigue life is investigated by means of synchrotron radiation micro-CT. Although preliminary, our results suggest that the application of this technique for micro-voids detection within the glass short fibre polyamide reinforced samples offers unique possibilities of investigating the micro-scale internal structure of the samples but, at the same time, presents several criticalities at different stages of the analyses, ranging from specimen size to set-up configuration and threshold selection. A frank discussion of the critical issues encountered during the analyses supplements the presentation in an effort to help defining general guidelines for future developments in this field.