• Title/Summary/Keyword: 응력확대계수

Search Result 607, Processing Time 0.024 seconds

A Study on the Effect of Micro Defect on Stress Intensity Factor of Through-Crack by Boundary Element Method (경계요소법을 이용한 관통균열의 응력확대계수에 미치는 미소결함의 영향에 관한 연구)

  • Seong, Gi-Deuk;Yang, Won-Ho;Jo, Myeong-Rae
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.24 no.3 s.174
    • /
    • pp.560-566
    • /
    • 2000
  • Many researchers have dealt with the problems of fracture mechanics. Generally, these researches are concerned with crack in isotropic material without other micro defects. Actual structure, however, may contain micro defects as well as crack in manufacture processing or operation. If it contains mi defects near a crack, some different characteristics will be appear in fracture behaviors of the crack. This study examines the effect of the micro defect on stress intensity factor of center slant crack rectangular plate subjected to uniform uniaxial tensile stress. In this study, boundary element method(BEM) is used for analysis in stress intensity factor(SIF).

공구파손의 파괴역학적 해석에 관한 기초적 연구

  • 이태세
    • Proceedings of the Korean Society of Precision Engineering Conference
    • /
    • 1992.04a
    • /
    • pp.33-37
    • /
    • 1992
  • 구조물과 기계부품에 부하를 주는 하중은 여러가지 종류가 있고, 이에 따르는 파괴의 형식도 여러가지가 있다. 그중에서도 연강압연용 로울러, 베어링 레일등은 집중 압축하중을 받는데 이들 부재의 파괴사고가 빈번히 일어나고 잇다. 압축에 의한 파괴 중 frectting, 피팅등과 같은 마모 현상은 두 재료의 표면이 서로 미끌어질때 일어나며, 이것이 공구나 기계부품의 성능과 수명을 저하시키는 주원인이 되며, 이러한 궁구나 기계 부품을 수리 또는 교환을 하기위한 인적, 경제적 손실은 막대하다. 본 연구에서는 금형등 공구의 마모편이 발생되는 마지막 과정인 크렉의 성장을 고찰하기 위하여 Sub-surface크랙 모델을 설정하여 2차원 유한요소 법으로 경계층 근방에 크랙이 존재하는 반무한 평면에 집중하중이 작용할때의 응력확대계수를 해설하였는데, 일반화된 해석법으로 혼합모드에서의 응력확대계수를 결정하였다.

Stress Intensity Factor Analysis of Nozzle Considering Pressure and Heat Transfer on Crack Face (균열면에 작용하는 내압과 열전달의 영향을 고려한 노즐부의 응력확대계수 해석)

  • Jeong, Min-Jung;Kim, Yeong-Jin;Gang, Gi-Ju;Beom, Hyeon-Gyu;Pyo, Chang-Ryul
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.24 no.9 s.180
    • /
    • pp.2252-2258
    • /
    • 2000
  • In order to investigate the effect of nozzle on stress concentration in pressure vessels, three dimensional finite element analyses were performed. The results were compared with those for corresponding two dimensional axisymmetric finite element analyses. A three dimensional finite element model with a surface crack was also designed to evaluate the effect of internal pressure and heat transfer on crack face, and the resulting stress intensity factors from the finite element analyses were compared with those for ASME Sec. XI and Raju-Newman's stress intensity factor solution. As a result, the validity of currently available stress intensity factor solutions for a surface crack was reviewed in the presence of geometrical complexity, heat transfer and internal pressure.

Determination of $k_1$in Elliptic Crack under General Ioading Conditions (타원균열에 작용하는 일반적인 하중에서의 응력확대계수 계산)

  • An, Deuk-Man
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.21 no.2
    • /
    • pp.232-244
    • /
    • 1997
  • In this paper weight function theory is extended to the determination of the stress intensity factors for the mode I in elliptic crack. For the calculation of the fundamental fields Poisson's theorem and Ferrers's method were employed. Fundamental fields are constructed by single layer potentials with surface density of crack harmonic fundamental polynimials. Crack harmonic fundamental polynimials up to order four were given explicitly. As an example of the application of the weight function theory the stress intensity factors along crack tips in nearly penny-shaped elliptic crack are calculated.

The Computation of Stress Intensity Factor of the Crack on the Surface of the Pin Joint (핀으로 연결된 결합부분의 표면에 위치한 균열의 응력확대계수 계산)

  • 정동수;이기수
    • Proceedings of the Korean Society of Precision Engineering Conference
    • /
    • 1996.11a
    • /
    • pp.921-927
    • /
    • 1996
  • The purpose of this study is to compute the stress intensity factors of various conditions in the cracked p! ate. The stress intensity factor of pin-loaded cracked plate is investigated using the finite element method. This paper is divided into the two parts. The first part is the contact analysis, and the second is to compute the stress intensity factors. In the contact analysis, the iterative method is used, and convergence of this method is presented. In the computation of the stress intensity factors of plate, the length of crack, clearance, and angle are considered

  • PDF

Analyses of Stress Intensity Factors for Slant Crack Emanation from Circular Inclusion by Boundary Element Method (경계요소법에 의한 원형함유물에서 파생되는 경사균열의 응력확대계수 해석)

  • Park, Sung-Oan;Hwang, Soon-Won
    • Journal of the Korean Society of Manufacturing Technology Engineers
    • /
    • v.7 no.5
    • /
    • pp.72-84
    • /
    • 1998
  • In order ot study the influence of a circular inclusion on a stress field near a crack tip, mutual interference of a slant crack and the circular inclusion is analyzed of a bimaterial inclusion. As the crack emanates at the equivalent slant crack angle the correction factors FⅠ and FⅡ for the inclusion wit small Young's modulus were found to decrease as the inclusion radius increased. The correction factors for inclusion with large Young's modulus increase as the inclusion radius increases at the equivalent radius of the inclusion, the correction factors decrease as the slant crack angle increases for the aspect ratio $\frac{c}{W}$ = 0.1 irrespective of the Young's modulus. For $\frac{c}{W}$ greater than 0.2, they increase as the slant crack angle increases. There is no influence of stress mutual interfce after crack emanates beyond the inclusion radius.

  • PDF

Stress Intensity Factor Analysis for Surface Crack in Inhomogeneous Materials (비균질재료의 표면균열에 대한 응력확대계수 해석)

  • 김준수;이준성
    • Proceedings of the Korean Society of Precision Engineering Conference
    • /
    • 2002.10a
    • /
    • pp.816-819
    • /
    • 2002
  • Accurate stress intensity factor analyses and crack growth rate of surface-cracked components in inhomogeneous materials are needed for reliable prediction of their fatigue lift and fracture strengths. This paper describes an automated system for analyzing the stress intensity factors of three-dimensional (3D) cracks in inhomogeneous materials. 3D finite element method (FEM) was used to obtain the stress intensity factor for subsurface cracks and surface cracks existing in inhomogeneous materials. To examine accuracy and efficiency of the present system, the stress intensity factor for a semi-elliptical surface crack in a plate subjected to uniform tension is calculated, and compared with Raju-Newman's solutions. Then the system is applied to analyze cladding effect of subsurface cracks in inhomogeneous materials. The results were compared with those surface cracks in homogeneous materials. It is clearly demonstrated from these analyses that the stress intensity factors for subsurface cracks are less than those of surface cracks.

  • PDF

An Inspection on Stress Intensity Factor of Center Crack Tip by Superposition Method (중첩법에 의한 중앙 크랙 선단의 응력확대계수에 관한 검증)

  • 한문식;조재웅;이양섭
    • Transactions of the Korean Society of Automotive Engineers
    • /
    • v.11 no.2
    • /
    • pp.172-181
    • /
    • 2003
  • In this study, the stress intensity factor of center crack tip is calculated by the superposition method when it is surrounded by symmetrically distributed small cracks. The values of stress intensity factors of center crack tips are compared with those of the center crack tips calculated by the superposition method. These compared errors are influenced by the locations of distributed small cracks. These errors are inspected. When small cracks overlap and approach near the center crack tip, the effect of interaction caused by these cracks becomes noticeable and these errors become larger. In case of multiple distributed small cracks except this case, the stress intensity factor of the center crack tip is easily calculated by the superposition method.

Mode I and Mode II Stress Intensity Factors for a Surface Cracked in TiN/Steel Under Hertzian Rolling Contact (Hertzian 접촉하중시 TiN/Steel의 표면균열에 대한 모드 I과 모드 II 응력확대계수)

  • Kim, Byeong-Su;Kim, Wi-Dae
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.25 no.8
    • /
    • pp.1163-1172
    • /
    • 2001
  • The two dimensional problem of a layered tribological system(TiN/Steel) containing a vertical surface breaking crack and subject to rolling contact is considered in this study. Using finite elements and stress extrapolation method, a series of preliminary models are developed. Preliminary results indicate that the extrapolation technique is valid to determine Modes I and II stress intensity factors for cracks. In the case of TiN/Steel medium, KI and KII were determined for variations in crack length, layer thickness, and load location. The results show that KII reaches maximum values when the contact is adjacent to the crack where Mode I stresses are compressive. KII values decrease with decreased crack length and significantly decrease for reduced layer thickness.

Effect of Residual Stress on Fatigue Characteristics at the Welds of Stainless Steel (스테인리스강 용접부의 잔류응력이 피로특성에 미치는 영향)

  • 권종완;양현태
    • Transactions of the Korean Society of Machine Tool Engineers
    • /
    • v.10 no.5
    • /
    • pp.110-117
    • /
    • 2001
  • In the weldments, the crack propagation rate is changed due to the residual stress. The crack propagation rate is high in the region with the residual stress. However it shows the same behavior with the base metal in the region that does not include the residual stress. The fatigue crack growth rate for the material with residual stresses can be predicted more precisely by using the effective stress ratio. The difference between experimental results and prediction results seems to be due to the redistribution of the residual stresses and microstructural change.

  • PDF