Adhesive Bond Integrity of Composites

Adhesive joining of materials has found widespread use in industry because of the simplicity and versatility of the process. However, adhesive applications in critical structural joints are still limited by the absence of reliable, rapid industrial NDE methods. Significant progress has been achieved recently in several research laboratories in quantitative NDE of adhesive joint integrity of metals. The most advanced ultrasonic techniques of adhesive joints utilize spectral analysis at oblique incidence. We propose to demonstrate the possibility of oblique ultrasonic spectroscopy for adhesive bond integrity evaluation of composites. The major differences from the evaluation of the metal joints are the laminated structure of the composites and the anisotropy of the laminates. Theoretical modeling will be performed to optimize the measurement technique, followed by ultrasonic and mechanical tests. Thus the correlation between ultrasonic signature and joint strength will be established.