Application of ultrasonic C-scan techniques for tracing defects in laminated composite materials

Abstract

In this paper practical ultrasonic C-scan techniques for NDT of laminated composite materials are developed and applied, with an aim to trace specific artificial defects. Two types of materials are examined; an advanced carbon/epoxy system and a typical marine type glass/polyester system. Both were constructed with two manufacturing methods (Hand Lay-Up and Vacuum Infusion). Several artificial defects were embedded into the test plates, varying in shape, magnitude and through thickness position. Test plates were C-scanned using ULTRAPAC II ultrasonic system with ULTRAWIN software and typical examination techniques (layer to layer examination, full width examination, etc.) were used to determine and characterize defects. In addition, appropriate software tuning procedures and examination strategies were applied, which further developed and optimised tthe scanning procedure. These efforts resulted in effective C-scan images, allowing the determination of the position and even the shape of the defects in some cases. Finally, precise determination of specimens' thickness was achieved.