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Creep-Fatigue Life Design with Various Stress and Temperature Conditions on the Basis of Lethargy Coefficient

응력 및 온도 변화시 무기력계수를 이용한 크리프-피로 수명설계

  • Park, Jung-Eun (Dept. of Mechanical System Engineering, Chonbuk Nat'l Univ.) ;
  • Yang, Sung-Mo (Dept. of Mechanical System Engineering, Chonbuk Nat'l Univ.) ;
  • Han, Jae-Hee (Dept. of Mechanical System Engineering, Chonbuk Nat'l Univ.) ;
  • Yu, Hyo-Sun (Dept. of Mechanical System Engineering, Chonbuk Nat'l Univ.)
  • 박정은 (전북대학교 기계시스템공학부) ;
  • 양성모 (전북대학교 기계시스템공학부) ;
  • 한재희 (전북대학교 기계시스템공학부) ;
  • 유효선 (전북대학교 기계시스템공학부)
  • Received : 2010.07.05
  • Accepted : 2010.12.16
  • Published : 2011.02.01

Abstract

High temperature and stress are encounted in power plants and vehicle engines. Therefore, determination of the creep-fatigue life of a material is necessary prior to fabricating equipments. In this study, life design was determined on the basis of the lethargy coefficient for different temperatures, stress and rupture times. SP-Creep test data was compared with computed data. The SP-Creep test was performed to obtain the rupture time for X20CrMoV121 steel. The integration life equation was considered for three cases with various load, temperature and load-temperature. First, the lethargy coefficient was calculated by using the obtained rupture stress and the rupture time that were determined by carrying out the SP-Creep test. Next, life was predicted on the basis of the temperature condition. Finally, it was observed that life decreases considerably due to the coupling effect that results when fatigue and creep occur simultaneously.

Keywords

Coupling Effect;Creep-Fatigue;High Cr-Mo Steel;Integration Life Equation;Lethargy Coefficient

Acknowledgement

Supported by : 한국산업기술진흥원

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