Simulation and Experimental Study of Ultrasonic Signals from lap Joints in the Presence of Nonuniform Thickness Values

The development of several NDE techniques today is focused on detecting and quantitatively assessing flaws such as disbonds, corrosion, and cracks for ensuring structural integrity of aging commercial aircraft. The ultrasonic contact scanning technique is one such technique that is currently under development due to its portability, ease of use, and ability to detect small flaws. Other NDE techniques that are also being used and developed are thermography, magneto-optics, shearography, electromagnetics, and radiography. This paper focuses on the ultrasonic contact scanning technique and presents a systematic study of the influence of thickness nonuniformity of the adhesive layer in lap joints and doubler joints, on the signals acquired using the technique.