TFM Direct 모드 영상을 이용한 결함 기울기 및 깊이 측정 연구

국문 초록 (Abstract)

위상배열초음파탐상검사(Phased Array Ultrasonic Testing;PAUT)의 새로운 기법인 FMC(Full Matrix Capture)/TFM(Total Focusing Method)기법은 후처리를 통해 결함에 따라 다양한 모드를 적용해 영상화가 가능하다는 장점을 가지고 있다. 하지만 결함의 기울기와 깊이에 따라 영상화 결과가 상이하여 조건 선정에 어려움이 있으며, 종파와 횡파의 속도 차이로 인해 무관련 지시가 나타나 건전부와 결함을 오인하는 문제가 발생한다. 따라서, 횡파 및 종파 웨지를 사용하여 TFM 다중모드 영상화 결과를 분석하여 결함의 기울기와 위치를 명확하게 검출할 수 있는 모드를 선별하고 무관련 지시의 신호 특성을 파악하는 연구가 필요하다. 본 연구에서는 결함의 기울기와 깊이가 TFM 영상에 미치는 영향을 파악하기 위해 탄소강에 70°부터 110°까지 10°간격의 기울기를 가지는, 1, 3, 5, 7, 9 mm의 다양한 깊이의 인공 결함을 방전 가공하여 제작하였다. 해당 시험편을 대상으로 횡파 및 종파 웨지를 이용한 TFM Direct 모드 적용 결과 실제 실험 결과와 시뮬레이션 결과를 비교 분석하였으며, 결함의 기울기에 따른 깊이 분석에 TFM Direct 모드의 유용성을 검증하였다.

다국어 초록 (Multilingual Abstract)

The full matrix capture (FMC) technique used in phased array ultrasonic testing (PAUT) collects all the transmitted and received information generated at the phased array transducer elements in the form of A-scan data without using the typical focal law. The total focusing method (TFM) is proposed here as a means to detect defects through a combination of various modes by post-processing and imaging the data acquired via FMC with improved clarity and resolution at the virtual region of interest (ROI), which is equivalent to PAUT. The combination of longitudinal and transverse modes allows the imaging of defects with varying slopes and depths, depending on the mode used. In this study, test samples with different defect slopes and lengths were prepared using longitudinal and transverse wave wedges, and the usability of the proposed method was verified by comparing the TFM direct mode test results and CIVA simulation results.

목차 (Table of Contents)

• 초록
• Abstract
• 1. 서론
• 2. 관련 이론
• 3. 실험장치 및 방법
• 4. 실험결과 및 고찰
• 5. 결론
• References

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