Non-contact Thickness Gauging Method based on Frequency Analysis using Underwater Ultrasonic for Steel Structures
* Presenting author
Periodic measurement of thicknesses of steel plates used at port structures is important to keep their durability. Non-contact thickness gauging system using ultrasonic for underwater steel structures has been proposed. However, high accuracy gauging is difficult under low signal-to-noise ratio (SNR) because received signals are analyzed in time domain. In this paper, the novel non-contact measurement method based on frequency analysis is proposed for solving above problem. In this method, the thickness of a steel plate is calculated by analyzing the period of multiple reflection occurred in a steel plate in frequency domain. Because the power of noise is averaged in frequency domain, influence of noise such as a sparse signal could be reduced. Moreover, because frequency resolution could be determined arbitrarily, it is expected to perform high performance measurement. The performance of the proposed method was evaluated using experimental data. As the result, the thickness of steel plate could be measured with the error less than 1 mm in SNR of 0 dB, and it is confirmed the availability of the proposed method.