Quantitative nondestructive evaluation of voids in CFRP laminates by stereo X-ray images

A simple nondestructive evaluation technique has been developed to provide a three-dimensional view of defects in carbon fiber reinforced plastics in our prior work. This technique produces a three-dimensional image by reconstruction of a doublet of stereo X-ray pictures. By the technique, delaminations in composites could be identified very accurately. However, there were problems in accuracy as for evaluation of voids in composites. Therefore we carried out two improvements: to detect the edge of the void image after enlarging the X-ray pictures, and to recombine a triplet of the stereo X-ray pictures for reconstruction of the three-dimensional image. The improvements provided satisfactory results. If the shot angles of stereography are appropriately selected, even a doublet of the stereo X-ray pictures can produce the three-dimensional image of the void accurately. (author)