Structural Health Monitoring Based on Laser Plasma Acoustic Excitation and Acoustic Measurement

Abstract

This paper proposes a health monitoring system for detecting a hole opened on a pipe based on laser plasma acoustic excitation and acoustic measurement. In this system, the acoustic excitation is applied to the pipe by the laser-induced plasma in the air, which is generated by a high-power Nd: YAG pulse laser. Non-contact acoustic impulse excitation can be realized by laser-induced plasma. A microphone is used for measuring the time response of acoustic pressure. In this study, the detection of the hole on the pipe is focused. The time response of acoustic pressure changes due to reflection of acoustic wave caused at the hole opened on the pipe. The position of the hole is identified by applying continuous wavelet transform to time response of with/without the hole.