Journal of The Korean Society For Urban Railway (한국도시철도학회논문집)

The Korean Society for Urban Railway (한국도시철도학회)
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Residual Stress Analysis of New Rails Using Contour Method

굴곡측정법을 이용한 신 레일의 잔류응력 분석

  • Song, Min Ji (Department of Materials Science and Engineering, Chungnam National University) ;
  • Choi, Wookjin (Department of Materials Science and Engineering, Chungnam National University) ;
  • Lim, Nam-Hyoung (Railroad Research Institute, Chungnam National University) ;
  • Kim, Dongkyu (School of Mechanical Engineering, University of Ulsan) ;
  • Woo, Wanchuck (Neutron Science Center, Korea Atomic Energy Research Institute) ;
  • Lee, Soo Yeol (Department of Materials Science and Engineering, Chungnam National University)
  • 송민지 (충남대학교 신소재공학과) ;
  • 최욱진 (충남대학교 신소재공학과) ;
  • 임남형 (충남대학교 철도연구소) ;
  • 김동규 (울산대학교 기계공학부) ;
  • 우완측 (한국원자력연구원 중성자과학연구센터) ;
  • 이수열 (충남대학교 신소재공학과)
  • Received : 2018.11.19
  • Accepted : 2018.12.10
  • Published : 2018.12.30
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Abstract

It is well recognized that residual stresses of the rails, generated from the manufacturing process including roller straightening and heat treatment, play an important role in determining fatigue and fracture properties of the rails. Thus, it has been a challenge to measure the residual stresses accurately. In this work, contour method was employed to evaluate the residual stresses existing in interior of the rails. The cross section perpendicular to the longitudinal direction of the rail was cut at a very slow rate using electric discharge machining (EDM), after which a laser-based flexural measuring instrument enabled us to precisely measure the flection of the cross section. The measured data were converted into the residual stresses using the commercial finite element package, ABAQUS, through a user-defined element (UEL) subroutine, and the residual stresses of the new rails (50N, KR60, UIC60) with three different specifications were compared.

레일의 잔류응력은 레일의 피로 및 파괴 특성에 영향을 끼치는 인자로서, 레일의 가공 및 열처리 등 생산 과정 단계에서 이미 형성되며, 이를 정확하게 분석하는 기술은 매우 중요한 문제이다. 본 연구에서는 레일 내부에 존재하는 잔류응력을 측정하기 위하여, 잔류응력 분석방법의 하나인 파괴법 기반 굴곡측정법을 적용하여 레일 축 방향의 잔류응력을 평가하였다. 레일의 축 방향과 수직한 단면을 방전가공을 사용하여 느린 속도로 단면을 절단한 후 레이저 기반인 굴곡 측정기를 이용하여 단면의 굴곡을 정밀 측정하였다. 측정된 데이터는 유한요소해석 프로그램 ABAQUS를 활용하여 설정한 요소로 잔류응력으로 변환시켰으며, 총 3종의 다른 규격을 갖고 있는 신 레일 (50N, KR60, UIC60)의 잔류응력 값의 경향과 수치를 비교하였다.

Keywords

Acknowledgement

Supported by : 국토교통부

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