서지주요정보
크리프 변형재료에서 손상을 고려한 모드 I 정지균열의 응력장 해석 = Analysis of the stationary mode I crack in creeping solids coupled with damage
서명 / 저자 크리프 변형재료에서 손상을 고려한 모드 I 정지균열의 응력장 해석 = Analysis of the stationary mode I crack in creeping solids coupled with damage / 김진영.
발행사항 [대전 : 한국과학기술원, 2002].
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소장정보

등록번호

8013294

소장위치/청구기호

학술문화관(문화관) 보존서고

DME 02003

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리뷰정보

초록정보

A crack tip stress field coupled with damage of stationary mode I crack is studied by mathematical and numerical methods. The damage effect is incorporated into the power-law creep constitutive equation by using the strain equivalence principle and the evolution of the cumulative damage is described by the multi-axial Kachanov-Rabotnov kinetic equation. Based on the regular perturbation approach the interaction between crack and damage has been investigated in case of small damage region around the crack tip. Taking a dimensionless coefficient as a perturbation parameter, which characterizes the concerned damage scale, a series of asymptotic solution is obtained with the zeros order approximation being the HRR type of solution. According to the solution, in the small region around a crack tip the HRR type singularity still dominates the solution with damage effect as only a perturbation. In case of large damage in the region very near the crack tip, numerical procedure do not work so easily because of the localization of damage. Thus, analytical procedures is employed to obtain the locally asymptotic structure of the solution that applies to the regime very near the crack tip. Within this regime the damage effect dominates the local zone. A coordinate perturbation approach is used to deal with the asymptotic behavior of crack tip stress field. And eigenvalues which represent the crack tip singularity are obtained with variation of material constants. According to the solution, stress vanish with coordinate r approaches zero due to damage relaxation to them. Consequently no stress singularity occurs and stress approach zero according to r(5-2 where s is a positive eigenvalue larger than 2. Eigenvalue shows a large dependency on the creep exponent and damage constants. Since global analytical solution is actually impossible to attain for this problem, finite element method is used. For this purpose, finite element program which can perform the structural analysis with viscoplastic constitutive equation having arbitrary scalar and tensor state variables is developed and FEM program is used to investigate the crack tip stress field with damage coupling. In analysis, CCP type specimen is considered. According to result, at the crack tip stress vanish and then increase with the increasing of r and finally they reach their corresponding maximum at some position from the crack tip. After that stresses decrease with the increase of r approximately according to the law predicted by HRR solution. The damage distribution on the other hand, shows its maximum value at the crack tip and apart from the crack tip, mesovolume element of the medium persist in a small damage state. As the time continues to increase the damage constantly accumulates in the crack tip region.

서지기타정보

서지기타정보
청구기호 {DME 02003
형태사항 x, 120 p. : 삽도 ; 26 cm
언어 한국어
일반주기 부록 : A, 미소손상문제에서 수식유도에 사용된 함수. - B, 과대손상문제에서 수식유도에 사용된 함수
저자명의 영문표기 : Jin-Young Kim
지도교수의 한글표기 : 이순복
지도교수의 영문표기 : Soon-Bok Lee
학위논문 학위논문(박사) - 한국과학기술원 : 기계공학전공,
서지주기 참고문헌 : p. 53-59
주제 크리프
손상역학
균열
응력특이성
유한요소해석
creep
damage mechanics
crack
stress singularity
FEM
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