Reconstruction of direct waves between passive flexible sensors using diffuse ultrasonic waves

• Published in: E-journal of Nondestructive Testing Vol. 29; no. 7
• Main Authors: LAI, Wenxin, Xu, Shuang, LUO, Zechen, CHEN, Paixin, YAN, Honglin, Kai WANG, Kai
• Format: Journal Article
• Language: English
• Published: 01.07.2024
• ISSN: 1435-4934; 1435-4934
• DOI: 10.58286/29686

The sensing system that enables generation and sensing of guided ultrasonic waves (GUWs) serves as a pivotal cornerstone for the structural health monitoring based on GUWs. Traditional sensing systems have been constrained by inherent limitations including substantial mass addition and limited flexibility, and this leads to an increasing research efforts for the emerging nano-composite sensors. Despite the superior properties of lightweight and flexibility, the nano-composite sensors is incapable of active wave excitation, and thus waves propagating directly between sensors cannot be obtained. To tackle this deficiency, an approach grounded in representation theorem to reconstruct signals using diffuse ultrasonic waves is proposed. In this approach, the waves propagating between two passive sensors can be approximated through the cross-correlation of wave signals in a diffused status. On this basis, the passive sensors can be virtually converted to active actuators, enabling the acquisition of waves virtually excited and captured by a pair of passive sensors. In experimental validations, the wave signals between passive sensors are retrieved and the damage close to the sensing path is detected. The proposed method enhances signal acquisition capability of sensing networks based on flexible passive sensors and opens avenues for the monitoring of previously inaccessible blind areas within complex structures.