• 제목/요약/키워드: 응력계수

Search Result 2,234, Processing Time 0.023 seconds

A Study on Stress Concentration Factor at Fillet Welded Joint (필렛용접이음부의 응력집중계수에 관한 연구)

  • S.W. Kang;W.I. Ha;J.S. Shin;J.S. Jae
    • Journal of the Society of Naval Architects of Korea
    • /
    • v.33 no.3
    • /
    • pp.1-7
    • /
    • 1996
  • The stress concentration factor gives the significant effect the fatigue strength of welded joints. The model used herein is the type of the load carrying fillet welded cruciform joint with full or partial penetration. In order to obtain the stress concentration factor at the weld toe of fillet joint, the reasonable element size of the toe part is investigated and the stress analysis for the series models by FEM under tensile load is performed. On the basis of the calculation results, the estimated formulae for the stress concentration factor(Kt) at weld toe part of the fillet welded joint, which the effect of toe radius, flank angle and other parameters are taken into account, is derived.

  • PDF

Stress Intensity Factors of Center Cracked Laminated Composites under Uniaxial Tension (단순인장을 받는 복합 적층재 중앙균열의 응력확대계수)

  • 김성호;오재협;옹장우
    • Transactions of the Korean Society of Mechanical Engineers
    • /
    • v.15 no.5
    • /
    • pp.1611-1619
    • /
    • 1991
  • 본 연구에서는 Hilton과 Sih의 경우를 확장 적용하여 Fig. 1(b)와 같이 탄성 층 내부에 존재하는 중앙균열선단의 응력확대계수 산출을 위하여 균열부위를 제외하고 는 섬유층과 레진층이 완전히 접착되었다고 가정한 모델을 다음과 같이 설정하였다. 중앙균열을 내재하고 있는 복합재료의 역학적 거동을 해석하기 위하여, 접착레진을 주 로하는 층(resin rich layer)을 중심으로 하여 상하 각1개의 섬유 (fiber)층과 균질한 특성을 갖는 복합재료의 층으로 단순화 하였으며, 이러한 단순화는 적층재에서의 균열 주위의 국부응력을 해석하기 위한 것으로서 복합재료는 레진층이나 섬유층에 비하여 매우 두꺼우므로 반무한체로 이상화 하였다. 선형탄성 이론에 의하여 혼합 경계조건 문제(mixed boundary value problem)로 부터 제2종 Fredholm적분방정식(fredholm int- egral equation of a second kind)을 유도하였으며 수치해석적인 방법에 의하여 응력 확대계수를 구하였다.

A Study on the Determination and Characteristics of Stress Intensity Factors and Stress Singularities for V-notched Cracks in Dissimilar Materials (이종재료간 V-노치균열의 응력특이성과 응력강도계수의 특성 및 결정에 관한 연구)

  • 조상봉;윤성관
    • Transactions of the Korean Society of Mechanical Engineers
    • /
    • v.16 no.10
    • /
    • pp.1890-1899
    • /
    • 1992
  • In bonded structures, there are V-notched cracks in dissimilar materials and the stress concentration of these V-notched cracks causes to occur interface cracks in dissimilar materials Therefore the strength evaluation of V-notched cracks in dissimliar materials seems to be important. The stress fields of a V-notched cracks is known as .sigma.$_{ij}$ .var. K $r_{p-1}$,where K is the stress intensity factor and p-1 is the stress singularity. When the distance, r, approaches to 0 at the stress fields of V-notched cracks, the stresses become infinites by two more stress singularities of p-1 and p-1 is no more -0.5. Stress singularities and stress intensity factors for V-notched cracks in dissimilar materials are treated and discussed. The Newton-Raphson method which is an efficient numerical method for solving a non-linear equation is used for solving stress sigularities. And stress intensity factors are solved by the collocation method using the Newton-Raphson and least squares method. The effects of stress intensity factors and stress singularities on stress fields of V-notched cracks in dissimilar materials are studied by using photoelasic isochromatic frings patterns obtained from computer graphics.s.

Reliability Analysis of Tripod Support Structure for Offshore Wind Turbine using Stress Concentration Factor (응력집중계수를 이용한 해상풍력터빈 트라이포드 지지구조물의 신뢰성해석)

  • Lee, Sang Geun;Kim, Dong Hyawn
    • Journal of Korean Society of Coastal and Ocean Engineers
    • /
    • v.28 no.2
    • /
    • pp.92-100
    • /
    • 2016
  • Reliability analysis of tripod support structure for offshore wind turbine was performed. Extreme distribution function of peak response due to wind and wave loads was estimated by applying peak over threshold(POT) method. Then, stress based limit state function was defined by using maximum stress of support structure which was obtained by multiplying beam stress and concentration factor. The reliability analysis result was compared when maximum stress was calculated from shell element. Reliability index was evaluated using first order reliability method(FORM).

Fatigue Crack Propagation Characteristics in HAZ of A106 Gr B Steel Pipe Weldments (A106 Gr B강 배관용접부의 잔류응력해석 및 피로균열성장특성)

  • 김철한;배동호;김복기;조선영;홍정균;이범노
    • Proceedings of the KWS Conference
    • /
    • 1999.05a
    • /
    • pp.237-240
    • /
    • 1999
  • In this study, residual stresses of the weldment were calculated by finite element analysis(FEA) and experiment. And, the crack closure behaviour and fatigue crack growth characteristics in field of residual stress of A106 Gr B steel pipe weldment were investigated under various stress ratio. Obtained results are as follows. I) $K_{op}$ was independent of $K_{max}$, and load ratio in fatigue crack growth. 2) In variation of load ratio, the scatter band of crack growth curve was reduced by half considering crack closure. and 3) Neglecting crack closure behaviour, actual fatigue crack growth rate can be underestimated' and Actual fatigue crack growth rate can be overestimated by $K_{res}$, in tensile residual stress field.

  • PDF

Stress Intensity Factor Measurement of Inclined Crack in Tensile Plates by Use of Photoelasticity (광탄성법을 이용한 인장판의 경사균열 응력확대계수 측정)

  • Baek, Tae-Hyun;Lee, Chun-Tae;Kim, Young-Chul
    • Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
    • /
    • v.5 no.2
    • /
    • pp.215-222
    • /
    • 2015
  • This paper presents the measurement of stress intensity factors of inclined cracks by use of photoelasticity. The distributions of isochromatics near a crack tip of the specimen loaded by uniaxially tensile load are used for analysis. Accuracy and reliability is enhanced by twice multiplying and sharpening the measured isochromatics using digital image processing. Photoelastic results are compared with those obtained by finite element method. Good agreement between them shows that the photoelastic analysis is reliable.

Calculation of Stress Intensity Factor in a Rotor with a Breathing Crack (개폐균열을 갖는 회전체에서의 응력확대계수 계산)

  • 전오성;이종원;엄윤용;은희준
    • Transactions of the Korean Society of Mechanical Engineers
    • /
    • v.15 no.5
    • /
    • pp.1417-1425
    • /
    • 1991
  • 본 연구에서는 파괴역학적 개념을 도입하여 수평 회전체에 존재하는 횡방향 개폐균열의 모형을 설명하고 균열거동을 분석하였으며, 균열의 깊이, 회전속도 및 회 전방향에 따른 균열선단에서의 응력확대 계수를 계산하고 그 특성을 분석하였다.

Effect of Stress-Dependent Modulus and Poisson's Ratio on Rutting Prediction in Unbound Pavement Foundations (도로기초의 Rutting 예측에 미치는 응력의존 탄성계수와 포와송비의 영향)

  • Park, Seong-Wan
    • Journal of the Korean Geotechnical Society
    • /
    • v.23 no.3
    • /
    • pp.15-24
    • /
    • 2007
  • This paper will present a simple approach (or predicting layer deformation of unbound pavement materials with stress-dependent material properties. The approach is based on an uncoupled formulation in which the resilient and deformation response of unbound materials are considered separately. As a result, an uncoupled approach incorporating a resilient stiffness and Poisson's ratio model is able to simulate field measured deformation in pavement foundations. In addition, a sensitivity analysis is conducted to identify the significant factors in the stress-dependent modulus and Poison's ratio model. The predicted trends of deformation from this analysis are presented and discussed.

Rheological Characteristics of Polyaniline Suspension as an Electrorheological Fluid (전기유변유체로서의 폴리아닐린 현탁액의 유변학적 특성)

  • 권무현
    • The Korean Journal of Rheology
    • /
    • v.7 no.3
    • /
    • pp.203-210
    • /
    • 1995
  • 전기장 하에서 폴리아닐린/미네랄 오일 현탁액의 유변학적 특성에 관한 실험적인 연 구를 큐엣 셀 형태의 레오미터를 사용하여수행하였다. 폴리아닐린 현탁액은 전기장을 가해 줄 때 점도가 크게 상승하는 현상을 보였고 부피분율과 전기장의 3/2승에 비례하는 동적 항 복응력을 나타내었다. 작은 변형 진폭의 동적 상태 실험을 통하여 저장계수와 손실계수를 변형진폭, 변형의 구동 주파수 및 전기장의 함수로 나타내었다. 저장계수는 전기장을 증가시 킬 때 증가하나 손실계수(5wt%)는 약한 전기장 의존성을 보였다. 낮은 응력을 가해줄때의 크립과 회복곡선은 초기의 순간적인 변형 증가와 지연되는 변형 그리고 회복 불가능한 영구 적 변형으로 구성되어진다. 탄성 한계 항복응력은 전기장의 세기가 증가함에 따라 증가하였 다. 매우 작은 변형에서는 응력과 변형사이의 선형적 관계를 보여 고체와 유사한 거동을 나 타내었다.

  • PDF

A Study on Determination of Stress Intensity Factors for the Interface Crack in Dissimilar AnisotropicMaterials (이방성 이종재료의 접합계면 균열에 대한 응력확대계수 결정에 대한 연구)

  • 이갑래;조상봉;최용식
    • Transactions of the Korean Society of Mechanical Engineers
    • /
    • v.15 no.3
    • /
    • pp.887-897
    • /
    • 1991
  • 본 연구에서는 이와 같은 배경에서, Fig. 1(f)와 같이 가장 일반적인 이방성 재료가 접합된 경우의 응력확대계수를 명확히 정의하고, 수치해석법으로 구할 수 있는 외삽식을 제안한다. 또한, 탄성문제의 수치해석 방법으로 적은 요소의 분할로써 고 정밀도의 수치해석 결과를 얻을 수 있는 경계요소법(boundary element method:BEM), 특히 저자들이 개발한 복합재료에 대한 2차원 경계요소법 프로그램을 이용하여 이방성 이종재료 접합계면 균열의 응력확대계수를 해석하고, 복합재료내의 섬유방향에 대한 접합계면 균열의 정성적 거동을 고찰하고자 한다.