In situ X-ray tomography investigation on damage mechanisms in short glass fibre reinforced thermoplastics: Effects of fibre orientation and relative humidity

Damage mechanisms of reinforced polyamide 6,6 have been studied in 3D through in situ X-ray tomography tensile tests. 3D pictures of the microstructure have been taken during tensile tests to catch damage evolution in the bulk of material. The effects of relative humidity and orientation sampling are particularly investigated in this paper. Main mechanisms have been identified such as fibre failure, debonding, damage at fibre ends and matrix damage (cavitation, fibrillation, damage growth). Qualitative observations reveal that the mechanisms are very sensitive to orientation sampling and relative humidity of the specimen. A specific procedure was developed to propose a quantitative analysis of the results. This analysis shows that identified mechanisms not only have different proportions but also have different kinetics according to relative humidity and orientation sampling of the specimen.