KSCE Journal of Civil and Environmental Engineering Research (대한토목학회논문집)

Korean Society of Civil Engeneers (대한토목학회)
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Estimation of Velocities of Acoustic Signals and Source Locations in PSC Beam by Acoustic Emission

AE기법을 이용한 PSC보의 음파속도와 음원위치 산정방법

  • 윤석구 (서울산업대학교 토목공학과) ;
  • 이창노 (서울산업대학교 토목공학과) ;
  • 김은겸 (서울산업대학교 토목공학과)
  • Received : 2006.02.20
  • Accepted : 2006.07.05
  • Published : 2006.09.30
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Abstract

Experimental tests were performed to estimate velocities of the acoustic signals through prestressed concrete beam and source locations using acoustic emission (AE) techniques. Seven AE sensors are mounted on the surface of 5m length test beam with equal spacing and using Schmidt Hammer AE events are made at 18 locations. The velocities of AE signals are estimated using the time differences of arrival times and the distances between the source locations and the AE sensor locations. In addition, using the Least Square Method, the AE source locations are re-evaluated reversely using both of the arrival times and the velocities of AE signals. Test results show the average velocity of the AE signals is about 4,000 m/sec and the velocity decreased with the increase of the distance from source locations to AE sensors due to the effect of attenuation. Based on the estimation of the source locations, it is observed that the errors of source locations are decreased when the velocities of each AE sensor are used rather than the average velocity.

AE기법을 이용하여 PSC보부재에 대한 음파의 전파속도와 음원위치 산정방법의 타당성을 알아보기 위한 실험을 수행하였다. 이를 위해 길이가 5m 인 PSC보 콘크리트 표면에 7개의 AE센서를 부착하였으며, 슈미트 햄머를 이용하여 콘크리트 표면에 인위적인 충격을 가하였다. 음파의 전파속도는 각각의 AE센서로부터 감지한 음파의 도달시간 차이와 음원과 센서와의 거리 차이를 이용하여 산정하였다. 또한 각 AE센서로부터 감지된 음파의 도달시간과 음파의 전파속도를 토대로 최소제곱법을 이용하여 역으로 음원 발생위치를 산정해 보았다. 실험결과 프리스트레스트콘크리트 매질에 대한 음파의 평균전파속도는 대략 4,000 m/sec 정도이며, 음원과 AE 센서 사이의 거리가 길어짐에 따라 음파의 감쇠현상에 의해 속도가 감소되었다. 최소제곱법을 이용한 음원위치 산정결과, 음파의 전파속도를 전체 AE센서의 평균전파속도를 이용하는 경우보다, 각 AE센서로 부터 산정된 음파의 전파속도를 이용하는 경우 오차가 감소되는 것을 확인하였다.

Keywords

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