내열합금 구조품에서의 국부적 소성변형과 이중후방응력 경화 모델

Localized Plastic Deformation in Heat-Resistant Alloy and Combined Two-Back Stress Hardening Model

  • 윤수진 (국방과학연구소 1기술연구본부 5부) ;
  • 이상연 (국방과학연구소 1기술연구본부 5부) ;
  • 박동창 (국방과학연구소 1기술연구본부 5부) ;
  • 윤현걸 (국방과학연구소 1기술연구본부 5부)
  • 투고 : 2011.05.03
  • 심사 : 2011.09.08
  • 발행 : 2011.10.30

초록

본 논문에서는 유한요소해석을 통해 연소시험 과정 중 발생한 내열 구조품의 파단현상이 분석되었다. 구조 불안정성은 소성변형으로 인한 것으로 이는 급격한 열하중의 변화에서 비롯된 것이다. 한편 소성변형 국부화 현상을 이해하기 위해 구성방정식에 연속체 파손변수가 포함되었으며 또한 Armstrong-Frederick과 Phillips 경화식을 이용, 이중후방응력 구성방정식이 제안되었다. 따라서 본 모델은 광범위한 소성변형거동을 해석할 수 있는 토대를 마련하였다. 수치해석을 통해 소성변형 집중 현상은 지배적인 후방응력의 전개에 의존하는 것으로 나타났다. 또한 물체 내에서의 파손 현상은 소성변형 집중을 가속화하는 것으로 밝혀졌다.

In the present work, FEM analyses are carried out to investigate the fractures occurred within the structural part in the course of combustion experiment. The loss of structural integrity stems from the localized deformation and the damage induced due to a severe change in the thermal load. Moreover, the two-back stress evolution model is proposed using the Armstrong-Frederick and the Phillips' rules to depict the plastic deformation, and the continuum damage mechanics is also incorporated into the present model. It is noted that the present model is able to formulate a wide range of constitutive description with ease. The numerical results depicts that a severe strain localization and damage evolution can be obtained depending on the dominant back stress.

키워드

참고문헌

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