Performance assessment for fiber tracking of unidirectional carbon fiber reinforced plastic by digital image correlation of X-ray computed-tomography

Cross-sectional X-ray computed tomography of unidirectional carbon fiber reinforced plastic (CFRP) composites was performed at a synchrotron radiation facility. Fiber locations in each tomogram were identified and connected longitudinally via updated digital image correlation, from which a CFRP numerical model was automatically developed. Fiber-tracking accuracy was important for obtaining exact duplicates; thus, the performance was experimentally analyzed with two types of unidirectional CFRPs formed with circular or kidney-shaped cross-sectional carbon fibers. The accuracy improved and then converged to a certain value with decreasing distance between each tomogram. Better accuracy was obtained for the circular fibers. Average error in the estimated fiber locations was less than in the fiber diameter. However, errors caused overlapped fibers. The experimental results thus indicated that fiber-tracking accuracy had to be improved to develop duplicates without overlapped fibers.