Experimental  Study on the On-line Monitoring of Offshore Structures Using Acoustic Emission Technology

J. Ocean Eng. Technol. 1999;13(Suppl DB Error: no such field):73-82.

Experimental Study on the On-line Monitoring of Offshore Structures Using Acoustic Emission Technology

Won, Soon-Ho;Cho, Kyung-Shik;

음향방출법을 이용한 해양구조물의 온라인 감시에 관한 실험적 연구

원순호;조경식;

한국기계연구원 비파괴평가그룹;한국기계연구원 비파괴평가그룹;

Keywords: Acoustic Emission, Nondestructive Testing, Offshore Structures, Underwater, Attenuation Measurement

핵심용어: 음향방출, 비파괴시험, 해양구조물, 수중, 감쇠측정

Abstract

In this research, an experimental study is presented to check the possibilities of offshore structures monitoring using AE techniques. The underwater transducer and preamplifier are fabricated. And, it is proved that this unit can be used for the detection of AE in offshore structures. Wave propagation studies have shown that supplementary attenuations due to seawater are significantly reducing the detection range of the sensors. It excludes the possibility of offshore structures monitoring with a small number of sensors. We conclude that AE waves would be correctly detected for a path of about 3m. Tubular joints have been tested in air and underwater using simulated elastic wave. Ability of AE techniques to detect and locate cracks early in their evolution has been demonstrated. Several parameters of AE generation have been set in evidence. It has also been shown that crack development goes with an increase of AE parameter. Conclusively, it is shown that AE techniques can provide practical alternatives to present methods being used for inspection of deep-water offshore structures undergoing structural degradation due to fatigue crack growth.