Composites Research

The Korean Society for Composite Materials (한국복합재료학회)
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Detection of Fine Delamination in Glass Fiber Reinforced Polymer Analyzing Full Width Half Maximum of Superimposed Terahertz Signal

테라헤르츠 중첩 신호의 FWHM 분석을 통한 유리섬유 복합재료 내부 미세 박리 검출 기술

  • Kim, Heon-Su (Department of Mechanical Convergence Engineering, Hanyang University) ;
  • Park, Dong-Woon (Department of Mechanical Convergence Engineering, Hanyang University) ;
  • Kim, Sang-Il (Department of Mechanical Convergence Engineering, Hanyang University) ;
  • Kim, Hak-Sung (Department of Mechanical Convergence Engineering, Hanyang University)
  • Received : 2021.06.14
  • Accepted : 2021.06.22
  • Published : 2021.07.01
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Abstract

Full width half maximum (FWHM) analysis of superimposed terahertz (THz) signals in the glass fiber reinforced polymer (GFRP) was studied to detect fine delamination inside GFRP. The THz signals were measured for each fine delamination size inside the GFRP using the reflection mode of the terahertz time domain spectroscopy (THz-TDS) system. Then, the FWHM of the superimposed THz signal reflected at the fine delamination was extracted. Thereafter, the complex refractive index of the GFRP was measured using transmission mode of the THzTDS system. Based on this, the FWHM of the superimposed THz signal at the fine delamination were calculated and compared with respect to the fine delamination size. From the theoretically calculated superimposed signals, the relationship between the fine delamination size and the FWHM in the superimposed THz signal was derived. Consequently, the fine delamination size could be predicted through the analysis of the FWHM extracted from the THz signal at the fine delamination.

유리섬유 복합재료(GFRP) 내부 미세 박리에서 나타나는 테라헤르츠(THz) 중첩 신호의 FWHM 분석을 통한 미세 박리 검출 기술을 연구하였다. 테라헤르츠 시간영역 분광(THz-TDS) 시스템의 반사모드를 통해 유리섬유 복합재료 내부의 미세 박리 크기 별 THz 신호를 측정하였고, 미세 박리 위치에서 반사되어 검출되는 THz 중첩 신호의 Full Width Half Maximum (FWHM) 값을 추출하였다. 이후, 유리섬유 복합재료의 복소굴절률을 측정하여 미세 박리 크기에 따른 미세 박리 위치에서의 THz 중첩 신호 및 FWHM 값을 계산하여 비교하였다. 이론적으로 계산된 THz 중첩 신호로부터 미세 박리 크기와 중첩 신호에서의 FWHM 값의 상관관계를 도출하였으며, 미세 박리 위치에서의 THz 신호로부터 추출된 FWHM의 분석을 통해 미세 박리 크기를 예측할 수 있었다.

Keywords

Acknowledgement

본 연구는 방위사업청과 국방과학연구소의 지원으로 수행된 수중운동체 장기체류 특화연구실(UD200012DD)의 연구비 지원으로 수행되었습니다.

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