Transactions of the Korean Society of Mechanical Engineers A (대한기계학회논문집A)

The Korean Society of Mechanical Engineers (대한기계학회)
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Spherical Indentation Techniques for Creep Property Evaluation Considering Transient Creep

천이크리프를 고려한 구형압입 크리프 물성평가법

  • Lim, Dongkyu (Dept. of Mechanical Engineering, Sogang Univ.) ;
  • Lee, Jin Haeng (Reactor Mechanical Engineering Division, Korea Atomic Energy Research Institute) ;
  • Kim, Minsoo (Dept. of Mechanical Engineering, Sogang Univ.) ;
  • Lee, Hyungyil (Dept. of Mechanical Engineering, Sogang Univ.)
  • Received : 2013.03.12
  • Accepted : 2013.08.07
  • Published : 2013.11.01
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Abstract

Creep through nanoindentations has attracted increasing research attention in recent years. Many studies related to indentation creep tests, however, have simply focused on the characteristics of steady-state creep, and there exist wide discrepancies between the uniaxial test and the indentation test. In this study, we performed a computational simulation of spherical indentations, and we proposed a method for evaluating the creep properties considering transient creep. We investigated the material behavior with variation of creep properties and expressed it using regression equations for normalized variables. We finally developed a program to evaluate the creep properties considering transient creep. By using the proposed method, we successfully obtained creep exponents with an average error less than 1.1 and creep coefficients with an average error less than 2.3 from the load-depth curve.

기존 단축 크리프시험에서는 천이 크리프의 영향을 무시하고 정상상태 크리프만을 고려하기 때문에 실제 크리프 특성을 나타내지 못한다. 이에 본 연구에서는 천이크리프를 고려한 압입 크리프 물성평가법을 제시한다. 다양한 재료에 대해 구형압입시험 전산모사를 이용해 크리프 물성변화에 따른 거동을 살펴보고, 크리프 특성을 무차원 변수들의 회귀식으로 표현한다. 이를 토대로 천이크리프를 고려한 압입 크리프 물성평가 프로그램을 생성했다. 제시한 물성평가 프로그램을 통해 압입 하중-변위 곡선으로부터 크리프지수, 계수값들을 각각 1.1%, 2.3% 오차범위에서 예측할 수 있다.

Keywords

References

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