Fatigue damage prognosis in adhesive bonded composite lap-joints using guided waves

Adhesive bonding have been increasingly employed in composite structures owing to several advantages over mechanically fastened or riveted joints. Adhesively bonded composite lap joints not only yield light-weighted structures but also provide a more uniform stress distribution than riveted joints resulting in higher fatigue life. However, modeling the physics behind crack initiation and propagation inside bonded regions is challenging especially under fatigue loading. As a result, NDE techniques such as guided wave sensing is required to monitor composite lap-joints. In addition to monitoring the damage state, prediction of disbond area inside the joints or the remaining useful life of the structure is imperative. This paper discusses a guided wave sensing technique to monitor damage area in Glass Fiber Reinforced Plastic (GFRP) lap-joints. Further, a damage propagation model based on Paris law is developed to estimate remaining useful life in terms of the GW signal features. Finally, the remaining useful life of the lap-joint is predicted for lap-joints subjected to fatigue cycles.