Yongju Jun and Usik Lee*
The Journal of Mechanical Science and Technology, vol. 26, no. 1, pp.53-61, 2012

Abstract : For structural health monitoring (SHM) applications, this paper proposes a new baseline-free time reversal process (TRP)-based SHM technique. The newly proposed technique is characterized by two key features: the hybrid TRP (HTRP) and the diagnostic digital imaging method. In the conventional TRP (CTRP), the forward and backward processes are all conducted by the measurement using piezoelectric actuators and sensors. However, in the proposed HTRP, the backward process is conducted by the computer-aided computational approach while the forward process is conducted by the same measurement approach as used for CTRP. As a benefit of the computeraided backward process, some Lamb wave modes which do not carry any damage information can be removed to obtain the refined reconstructed signals which are finally used for the damage diagnosis: this can make the remaining signal processing for the damage diagnosis much efficient. In contrast to the previous CTRP-based damage diagnosis methods where the pattern comparison methods have been widely used, the digital imaging method is used in the proposed SHM technique to detect damages by using the time-of-arrivals of the wave packets generated by the damages.

Keyword : Damage; Digital imaging method; Hybrid time reversal process; Lame wave; Structural health monitoring; Time reversal method