Morphology characterization and in-situ three-dimensional strain field monitor of short carbon fiber-reinforced polymer composites under tension

In-situ Micro X-ray computed tomography (μCT) offers a new opportunity to monitor the 3D morphology and damage evolution of short carbon fiber-reinforced polymer (SCFRP) composite. However, the sample size of in-situ μCT is generally limited to achieve high revolution, which resulted in different mechanical behavior compared with that obtained from standard samples. In this study, μCT scans with two resolutions were combined to character the 3D geometrical morphology and monitor the 3D deformation fields of SCFRP composites under tension. High resolution μCT scans with voxel size of 0.68 μm were used to quantify the geometric characteristics of fibers and void defects inside small samples. Low resolution in-situ μCT scans with voxel size of 4 μm and digital volume correlation method were utilized to monitor the 3D deformation fields of standard specimens under tension. The failure behavior of SCFRP was determined by the micro geometric morphology. The fracture surface under tension is oriented along 120° and 240° in the XY plane, which is consistent with the fiber and debonding distribution.