와전류 열화상 전산시뮬레이션에 의한 구름접촉피로 결함의 열적 구배 특성 분석 = Analysis on Thermal Contrast Characteristics of RCF Defects by Eddy Current Thermographic FEA Simulation

다국어 초록 (Multilingual Abstract)

Rolling-contact fatigue(RCF) is a typical rail-failure-type defect and is mainly caused by excessive stress. This failure affects the durability and fatigue life of the rail, which in turn leads to rupture. Eddy current thermal imaging is a technique that locates an electromagnetic pulse on a conductor, locally generates resistance heat in the defective part, and measures the heat using an infrared camera. In this work, an eddy current thermal imaging model is developed, and the thermal-contrast characteristics of the RCF defects are analyzed. A simulation was performed considering the conditions of excitation frequency, current intensity, and distance between the coil and specimen using FEA(Software ANSYS 19.2 Maxwell 3D, Steady-State Thermal). Thus, the current-density and temperature-gradient data were extracted and comparatively analyzed.

국문 초록 (Abstract)

Rolling-contact fatigue(RCF)는 레일의 결함 발생 유형 중 대표적인 결함이며 주로 과도한 응력에 의해 발생한다. 이로 인해 레일의 내구성과 피로 수명에 영향을 미치게 되며 결과적으로 파단으로 이어진다. 와전류 열화상이란 전자기 펄스를 전도체에 가진하면 국부적으로 결함부에 저항열이 발생하며 이때 발생된 열을 적외선 열화상 카메라로 측정하는 기술이다. 본 논문에서는 와전류 열화상 시뮬레이션 모델러를 개발하였으며 RCF 결함의 열적 구배 특성 분석을 수행하였다. FEA(Software ANSYS 19.2 Maxwell 3D, Steady-State Thermal)를 활용하여 가진 주파수, 전류의 세기 및 거리의 변수 조건으로 시뮬레이션을 수행하였으며 결과로서 전류 밀도와 온도 구배 데이터를 추출하여 이에 대한 비교 분석을 수행하였다.

참고문헌 (Reference)

1 한순우, "철도 레일의 결함 검출을 위한 비파괴탐상 기술" 한국비파괴검사학회 31 (31): 398-413, 2011

2 I. Z. Abidin, "Quantitative evaluation of angular defects by pulsed eddy current thermography" 43 : 537-546, 2010

3 Y. He, "Pulsed eddy current technique for defect detection in aircraft riveted structures" 43 : 176-181, 2010

4 W. T. Kim, "Principle and applications of induction infrared thermography" 37 (37): 44-49, 2017

5 J. Wilson, "PEC thermography for imaging multiple cracks from rolling contact fatigue" 44 : 505-512, 2011

6 A. Taram, "Nondestructive testing of resistance spot welds using eddy current thermography" 57 (57): 63-68, 2018

7 D. Peng, "Modelling of the lock-in thermography process through finite element method for estimating the rail squat defects" 28 : 275-288, 2013

8 R. Yang, "Lateral heat conduction based eddy current thermography for detection of parallel cracks and rail tread oblique cracks" 66 : 54-61, 2015

9 J. Liu, "Investigation of thermal imaging sampling frequency for eddy current pulsed thermography" 62 : 85-92, 2014

10 J. Peng, "Investigation into eddy currnet pulsed thermography for rolling contact fatigue detection and characterization" 74 : 72-80, 2015

11 N. Biju, "Frequency optimization for eddy current thermography" 42 : 415-420, 2009

12 M. Pan, "Defect characterisation using pulsed eddy current thermography under transmission mode and NDT applications" 52 : 28-36, 2012

13 M. He, "Crack detection based on a moving mode of eddy current thermography method" 109 : 119-129, 2017