Enhanced nonlinear crack-wave interactions for structural damage detection based on guided ultrasonic waves

The paper presents a new damage-detection method based on nonlinear crack-wave interaction. Low-frequency vibration excitation is introduced to perturb damage, and high-frequency interrogating wave is used to detect damage-related nonlinearities. However, in contrast to other crack-wave interaction approaches, localised wave packets are used for high-frequency excitation. The synchronisation of the low-frequency vibration with the interrogating high-frequency wave packets is a key element of the proposed method. Numerical simulations and simple experimental tests in cracked aluminium beams are performed to demonstrate the method. The results show that the proposed method can detect and localise damage-related and intrinsic nonlinearities, allowing for reliable damage detection. The method does not require baseline measurements representing an undamaged condition, and it is not sensitive to temperature variations. Copyright (c) 2016 John Wiley & Sons, Ltd.