Design and performance validation of a compact wireless ultrasonic device for localized damage detection

Recent years have seen growing adoption of wireless structural sensor nodes that can significantly reduce the cost and installation effort of a structural health monitoring system. While previous wireless sensor development has mainly focused upon dynamic and vibration measurements at lower frequency domains, in this study, a new wireless ultrasonic sensing node capable of megahertz excitation and sampling is proposed. In addition to presenting the design of the wireless ultrasonic sensing node, experimental notch test and fatigue test of a dog-bone specimen are described in this article. The experimental results demonstrate that the ultrasonic characteristics of surface cracks can be identified in both scenarios with the proposed wireless sensor node. Furthermore, a signal processing procedure is proposed to obtain an accurate estimation of the ultrasonic signal amplitude, which can be a key indicator for crack identification. The procedure involves signal reconstruction with the cardinal sine function and envelope detection using discrete Hilbert transform.