Bondline and Kissing Bond Assessment using Acoustography

This research work aims to demonstrate the feasibility of applying a novel Acoustography technique for the semi-quantitative evaluation of bond shear strength and assessment of adhesive bond quality in airframe sandwich structures. The proposed approach will utilize thermal and mechanical excitation methods to separate the weak/kissing bonds in the adhesively bonded test coupons. Finite element analysis (FEA) will be conducted to design optimal thermal and mechanical excitation sources and to properly model the effects of disbonds in sandwich interface. Coupons consisting of composite epoxy panels bonded to a Ti-alloy, fabricated with predefined phantom disbond defects, shall be the primary focus of this study. A correlation between acoustography results for predicted bond quality in a range of appropriately flawed test specimens (initially fabricated and aged conditions) and the results of shear testing of the flawed specimens will be drawn. In addition, microstructure evaluation of the bonded samples will also be carried out. The proposed method will be portable, easy to use, and will possess the ability to conduct close-to-the-edge and round curvature inspection. In addition, this method will be more reliable for detecting weak/kissing bonds so as to enhance the reliability and reduce the costs during manufacturing and in-service operations.