Detection of Kissing Bond Like Defects in Composite Joints Using Guided Wave NDT and Laser Shock
Srinath Ramagiri, Jamil Kanfoud, Tat Hean Gan, Aggelos Christopoulos, George Kanterakis, Konstantinos Kitsianos, Pratik Shukla, Georgoios Liaptsis and Jonathan Laidler
A kissing bond is a defect where two surfaces are partially bonded or debonded, but still, touch or are in very close proximity. A kissing bond is also considered as a zero-volume dis-bond offering reduced shear strength. Although the reasons behind these defects are not clearly known, poor adhesion, environmental degradation, or impact damage are considered to be some common causes. A defect of this kind cannot be observed/ detected macroscopically, and because of their intimate contact, its detection using non-destructive techniques (NDTs) is more limited than that of conventional defects. It is important to devise a technique to detect these defects because, use of adhesives and adhesive joints is gaining importance in industries such as automobile, aerospace, defense, etc. The presence of these defects in bonded joints leads to catastrophic failure due to the nature of the defects. Destructive tests however detect these defects accurately but are not applicable on in-service assets. We in this work have attempted to create kissing bond like defects and detected them using guided wave NDT and laser shock techniques. For this purpose, bonded joints are created with and without the defects. Classical NDT tests and Mechanical tests are used to confirm the creation of bonded joints with the defects. Thus, a protocol is created to create bonded joints with kissing bonds like defects. Later, the bonded joints are tested using guided waves NDT, laser shock tests. Time signal of the bonded joints samples are analysed to detect the defect.
Keywords: Kissing bonds, non-destructive testing, guided waves NDT, laser shock