• Title/Summary/Keyword: 유한요소 해석

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Evaluation on Flexural Performance of Precast Decks with Ribbed Joint by FEM (유한요소해석에 의한 요철형 이음단면을 갖는 프리캐스트 바닥판의 휨성능 평가)

  • Oh, Hyun-Chul;Chung, Chul-Hun;Kang, Myoung-Gu;Park, Se-Jin;Shin, Dong-Ho
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.20 no.1
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    • pp.85-94
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    • 2016
  • In this study, a non-linear FEM model is presented to predict the static flexural performance of precast bridge decks with ribbed joint and is verified with previous experiment results through comparison. The several theory of material properties were applied to each mechanical properties in FEM model and FEM model's input variables were determined through experiment result and parametric study. The FEM results showed good accuracy in predicting the structural performance of the specimens and FEM model's average error rate was 5%. Also, each specimen's cracking aspect and failure mode can be predicted through FEM's plastic strain distribution. Thus, this FEM model can be used effectively for predicting the ultimate behavior and parametric study to development of design formula for joint.

Derivation of Elastic Stress Concentration Factor Equations for Debris Fretting Flaws in Pressure Tubes of Pressurized Heavy Water Reactors (가압중수로 압력관 이물질 프레팅 결함의 탄성 응력집중계수 수식 도출)

  • Kim, Jong Sung;Oh, Young Jin
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.38 no.2
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    • pp.167-175
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    • 2014
  • If volumetric flaws such as bearing pad fretting flaws and debris fretting flaws are detected in the pressure tubes of pressurized heavy water reactors during in-service inspection, the initiation of fatigue cracks and delayed hydrogen cracking from the detected volumetric flaws shall be assessed by using elastic stress concentration factors in accordance with CSA N285.8-05. The CSA N285.8-05 presents only an approximate formula based on linear elastic fracture mechanics for the debris fretting flaw. In this study, an engineering formula considering the geometric characteristics of the debris fretting flaw in detail was derived using two-dimensional finite element analysis and Kinectrics, Inc.'s engineering procedure with slight modifications. Comparing the application results obtained using the derived formula with the three-dimensional finite element analysis results, it is found that the results obtained using the derived formula agree well with the results of the finite element analysis.

Behavior of Geotextile Tube by Plane Strain Analysis and 3-Dimensional Finite Element Method (평면변형해석과 3-D FEM 기법을 통한 지오텍스타일 튜브의 거동해석)

  • 신은철;오영인
    • Journal of the Korean Geotechnical Society
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    • v.19 no.5
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    • pp.233-241
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    • 2003
  • Geotextile tube is hydraulically filled with dredged materials and has been applied to coastal protection and scour protection, dewatering method of slurry, and isolation of contaminated material. Recently, geotextile tube technology is no longer alternative construction technique but suitable desired solution. In this paper, the numerical analysis was performed to investigate the behavior of geotextile tube with various properties of geotextile sheet and hydraulic pumping conditions. Numerical analysis was executed to compare with the results from the large-scale field model tests, and also with those of plane strain analysis and 3-D FEM analysis. A geotextile tube was modeled using the commercial finite element analysis program ABAQUS and the one-quarter of tube was modeled. Behavior of geotextile tube during the hydraulic pumping procedure was analyzed by comparing the large-scale field model test and numerical analysis. The shape variation and maximum tube height between the numerical analysis results and large-scale filed test results are turned out to be in a good agreement.

A Optimal 3D FE Model for Evaluation of Peening Residual Stress Under Angled Multi-impacts (다중경사충돌시 피닝잔류응력 평가를 위한 최적의 3차원 유한요소모델)

  • Hyun, Hong-Chul;Kim, Tae-Hyung;Lee, Hyung-Yil
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.36 no.2
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    • pp.125-135
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    • 2012
  • The FE model for shot peening often assume that shots impact vertically on the engineering parts to generate compressive residual stresses. However, the shots obliquely impact on the surface in actual peening. In this work, we propose a 3D finite element (FE) model for evaluation of residual stress under angled shot peening. Using the FE model for angled multi-impact, we examine the effects of factors such as impact angle, impact pattern and the number of shots. Plastic deformation of shot is also considered. To validate the model, we then compare the FE solution with experimental result by X-ray diffraction (XRD). The proposed model will be a base of 3D multi-impact FE model with diverse impact angles.

Finite Element Analysis of the Electromagnetic System Considering the Rotational Hysteresis Characteristics (회전 히스테리시스 특성을 고려한 전자계의 유한요소 해석)

  • 홍선기;김홍규;정현교
    • Journal of the Korean Magnetics Society
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    • v.7 no.2
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    • pp.109-116
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    • 1997
  • This paper describes an implementation of the rotational hysteresis analysis using the finite element method and a vector hysteresis model. The vector hysteresis model is extended from the magnetization-dependent Preisach model. The magnetization of each element is calculated for a given history of the rotating field. The lagging angle and the magnitude of the magnetization for an applied field are evaluated. The experimental results show that the magnetization characteristics of the magnetic materials under the rotating field can be analyzed accurately by the proposed method.

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A Study on the Ultimate Strength and Behavior of Circular Section Subjected to Cross-Sectional Distortion (뒤틀림변형을 받는 관형단면의 극한강도 및 거동에 관한 연구)

  • Kim, Woo Bum
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.14 no.1
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    • pp.83-91
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    • 1994
  • An efficient method was developed to determine the ultimate strength for the segment subjected to cross-sectional distortion. Cumulative data based on the finite element analysis were used to perform the multi-regression analysis. A moment-thrust-curvature relationship of short segment was obtained with mathematical forms in the nonlinear range. The extensive parametric study was performed to generate the ultimate strength for the various segments. The result was compared with the experimental result which was not included in the database. The proposed method gives an essential tool for the nonlinear analysis of beam-column.

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Inverse Estimation of Fatigue Life Parameters for Spring Design Optimization (스프링 최적설계를 위한 피로수명 파라미터의 역 추정)

  • Kim, Wan-Beom;An, Da-Wn;Choi, Joo-Ho
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.345-348
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    • 2011
  • 구조요소의 설계에서 유한요소해석은 매우 효과적인 방법이다. 이 방법은 시험 수행에 드는 시간과 비용을 줄여준다. 그러나 공정 과정과 환경에 의하여 생기는 입력 물성치들의 변화 때문에 우리는 유한요소해석의 결과를 전적으로 믿어서는 안 된다. 따라서 유한요소해석의 신뢰성을 증명하는 것은 매우 중요하다. 본 연구에서는 현장에 축적된 피로 수명 시험 데이터를 바탕으로 유한요소해석을 이용하여 피로수명 파라미터를 역 추정 하는 연구를 수행하였다. 베이지안 접근법을 이용하여 불확실성 피로 수명 파라미터의 사후분포를 구하였고, 마코프체인몬테카를로(Markov Chain Monte Carlo) 기법을 이용하여 역 추정된 파라미터의 샘플 데이터를 생성하였다. 얻어진 샘플 데이터를 기반으로 새로운 형상의 스프링에 대한 피로 수명을 예측한다. 신뢰성 기반 형상 최적화(RBDO)는 서스펜션 코일 스프링의 요구수명을 만족시키기 위하여 수행된다. 또한 크리깅 근사 모델은 유한요소해석의 연산 량 감소를 위해 이용한다.

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Assessment of the Internal Pressure Fragility of the Wolsung Unit 1 Containment Building using Nonlinear Finite Element Analysis (비선형 유한요소 해석을 이용한 월성1호기 격납건물의 내압취약도 평가)

  • Hahm, Dae-Gi;Choi, In-Kil;Lee, Hong-Pyo
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.653-656
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    • 2010
  • 월성 1호기 격납건물에 대하여 극한내압하중에 대한 확률론적 취약도 평가를 수행하였다. 격납건물 성능의 불확실성은 가동중 검사 결과를 통해 얻어진 재료 물성치 중앙값과 텐던 긴장력 중앙값을 적용하여 고려하였다. 격납건물은 개구부를 고려하여 3차원 유한요소로 모델링하였으며, 확률론적 취약도 평가를 위하여 대규모의 비선형 유한요소 해석 모델을 적용하기에 적합한 효율적인 취약도 평가 기법을 개발하였다. 월성 1호기 격납건물에 대한 취약도 평가 결과, 벽체 중단부가 극한내압발생으로 인한 방사능물질 누출에 가장 취약한 것으로 나타났으며, 중앙값 성능은 약 55psi, 고신뢰도 저파괴 파괴확률값인 HCLPF(High Confidence Low Probability of Failure)는 약 29psi를 나타내었다.

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Prediction of Dynamic Characteristics of Small DC Motor (소형 직류 모터의 동특성 예측)

  • Kim, Kug-Weon;Ahn, Tae-Kil
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.7 no.2
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    • pp.107-112
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    • 2006
  • In this paper, described is a research on the modal analysis of small DC motor by finite element method fer the vibration reduction. An impact test is performed to obtain the natural frequencies and modal shapes of DC motor, which valuate the usefulness of the finite element analysis model. From the study, we show that this finite element analysis model can be applicable for designing a new motor with improvement in vibration characteristics. As an example, a shape modification of DC motor is performed and its vibration characteristics is discussed in comparison with those of original shape.

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