Ultrasonic and X-ray Inspection of a High Performance Carbon Fiber Composite for Automotive Applications

Abstract

Ultrasonic and radiographic inspections can be used to rapidly qualify carbon composites in automotive production environments as well as detect in-service damage. These evaluations have been demonstrated on high quality automotive thermoset composites with woven, unidirectional, and random-chopped carbon fibers and with a variety of layups including unidirectional, 0/90, and quasi-isotropic. The performance on flat plaques and flanged beams as well as adhesively-bonded assemblies has been assessed. High resolution ultrasonic imaging both with raster scanners and phased arrays can detect voids and foreign matter including the inter-ply location. Using ultrasonic 3-d datasets, the orientation of individual plies can be determined within areas as small as 30-mm. Three dimensional ultrasonic images have been compared with bi-directional SEM images of the same area. Ultrasonic imaging is especially useful for detecting non-visible collision damage. The differences found from impact, flex, and crush damage have been determined. 3-d renderings of the damage have been made. Low-energy radiography has even higher in-plane resolution and can detect features such as voids below 0.1-mm in size in regions as big as 30-cm. The ability of low-energy computed tomography to resolve ply information in component size regions has also been evaluated.