Structure damage localization with ultrasonic guided waves based on a time–frequency method

• A signal processing scheme is proposed to improve damage localization accuracy.
• Ultrasonic guided wave technique is combined with WVD-based time–frequency method.
• True time–frequency energy distribution is utilized in the proposed scheme.
• Damage imaging algorithm for two-dimension structure is developed based on SPWVD.
• The damage localization for beam and plate structures is experimentally verified.

The ultrasonic guided wave is widely used for structure health monitoring with the sparse piezoelectric actuator/transducer array in recent decades. It is based on the principle that the damage in the structure would reflect or scatter the wave pulse and thus, the damage-scattered signal could be applied as the feature signal to distinguish the damage. Precise measurement of time of the flight (TOF) of the propagating signal plays a pivotal role in structure damage localization. In this paper, a time–frequency analysis method, Wigner–Ville Distribution (WVD), is applied to calculate the TOF of signal based on its excellent time–frequency energy distribution property. The true energy distribution in the time–frequency domain is beneficial to reliably locate the position of damage. Experimental studies are demonstrated for damage localization of one-dimensional and two-dimensional structures. In comparison with traditional Hilbert envelope and Gabor wavelet transform methods, the proposed WVD-based method has better performance on the accuracy and the stability of damage localization in one-dimensional structure. In addition, the proposed scheme is validated to work effectively for damage imaging of a two-dimensional structure.