Publications Details

Non-Destructive Evaluation of the Bondline Interface between Carbon Fiber Reinforced Laminated Composites and Metal Materials via Ultrasonic Inspection Methods

Moore, David G.; Stair, Sarah L.; Jack, David A.; Nelson, C.L.

Woven fiber, laminated composites allow the design engineer to create high strength parts, but the effectiveness of the final processed part is greatly diminished through weak or nonexistent bonds between the composite and the substrate to which it is bonded. Additionally, these layered laminates are commonly made by curing the resin infused carbon fiber fabrics in predefined layers and then bonding them to another composite or a metallic structure using either a pre-cure or a co-cure method. The focus of this study is the identification of the defect caused by a disbond or a delamination located at the interface between a composite laminate stack and the substrate to which it is bonded. We present a nondestructive approach using various ultrasonic methods to identify the existence of the bond between composite and composite-to-metal interface. This paper explores contact and immersion ultrasound methods using pulse-echo for evaluating the composite material and adhesive bondline and the signal attenuation undergone by the wave as it propagates through the composite. Finally, a summary of the detection and analysis techniques developed to identify disbonds, including Fast Fourier Transform analysis of the immersion data, is presented. Lastly, each of the methods evaluated in this study is able to detect the transition from bonded to unbonded sections at the bondline from either side of the bonded part, with the immersion technique providing a significantly higher resolution of the edge of the bondline.