• Title/Summary/Keyword: Dynamic Finite Element Analysis

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A Numerical Analysis on Application of Laser Peening to Dissimilar Metal Welds in a Safety Injection Nozzle of Integral Reactor (일체형 원자로 안전주입 노즐 이종금속 용접부에 대한 레이저 피닝 적용의 수치 해석적 연구)

  • Seo, Joong-Hyun;Kim, Jong-Sung;Jhung, Myung-Jo;Ryu, Yong-Ho
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.36 no.6
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    • pp.599-608
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    • 2012
  • A numerical analysis has been performed through implicit dynamic finite element analysis using the commercial package, ABAQUS in order to investigate effect of laser peening on welding residual stress mitigation of dissimilar metal welds in a safety injection nozzle of integral reactor. The implicit dynamic finite element analysis are compared with the previous experimental results. By comparison, it is identified that the implicit dynamic finite element analysis is valid for residual stress mitigation via laser peening. Implicit static finite element residual stress analysis has been performed for the dissimilar metal welds subject to inner repair welding. The analysis results represent that both axial and hoop residual stresses are tensile on inner surface of safety injection nozzle due to inner repair welding. Also Parametric study has performed to investigate effect of laser peening variables such as maximum impact pressure, duration time of pressure, spot diameter and peening direction on the welding residual stress mitigation. As a result, it is found that laser peening has the preventive maintenance effect to mitigate mainly residual stresses of region near inner surface.

Ship Collision Analysis with Offshore Structure (선박과 해양 구조물의 충돌 해석)

  • Kim, Jong-Sung;Jung, Hyun;Ko, Jae-Yong
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2004.04a
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    • pp.169-176
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    • 2004
  • Offshore structure crossing navigation waterways must not only be designed to resist gravity, wind, and earthquake load, but also be capable of resisting ship and barge collision load. Current specifications for offshore structure design provide empirical relationships for computing impact loads generated during barge collision, however, these relationships are based on the limited experimental data. In this paper, the dynamic finite element analysis is used to computing force for vessel collision scenarios to offshore structures. Results obtained from the ANSYS/LS-DYNA are compared to AASHTO bridge design specifications.

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Impact Analysis of Short Fiber-Reinforced Metal Matrix Composites (단섬유 강화 금속 복합재의 충격 해석에 관한 연구)

  • 안국찬
    • Journal of the Korean Society of Safety
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    • v.9 no.3
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    • pp.3-12
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    • 1994
  • This study employed the Eshelby's equivalent inclusion method incorporated with mean field theory to investigate the Internal stress of short fiber-reinforced metal matrix composites during static loading and the dynamic finite element analysis by using alternative unit cell model to investigate the impact behaviors during the impact loading. Using the 2124 Al-SiC system as an example, the general effects of parameters such as fiber's aspect ratio, content and modulus were examined.

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A Comparative Study on Elastic-Plastic -Dynamci Analysis of Sheet Metal Forming (탄소성 동적해석시 해에 미치는 여러 인자들의 비교연구)

  • 박종진
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 1999.03b
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    • pp.245-248
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    • 1999
  • Explicit dynamic finite element analysis has been used widely in the field of sheet metal forming. However in using the analysis technique there are some parameters which are not clearly defined so that engineers may obtain inaccurate solutions In the present study parameters such as time step damping ratio penalty constant and punch speed were investigated on their influence to the solution behavior. Considered forming processes are plane stain bending by a punch and axisymmetric deep drawing.

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Moving Support Elements for Dynamic Finite Element Analysis of Statically Determinate Beams Subjected to Support Motions (지점운동을 받는 정정보의 동해석을 위한 동지점 유한요소 개발)

  • Kim, Yong-Woo;Jhung, Myung Jo
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.37 no.4
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    • pp.555-567
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    • 2013
  • A finite element formulation for a Rayleigh-damped Bernoulli-Euler beam subjected to support motions, which accompanies quasi-static rigid-body motion, is presented by using the quasi-static decomposition method. Moving support beam elements, one of whose nodes is coincident with the moving support, are developed to represent the effect of a moving support. Statically determinate beams subjected to support motions can be modeled successfully by using moving support elements. Examples of cantilever and simply-supported beams subjected to support motions are illustrated, and the numerical results are compared with the analytical solutions. The comparison shows good agreement.

Finite Element Analysis of Dynamic Deformation of Refrigerator's Lower Hinge during Drop Test (냉장고 낙하시 하힌지 동적변형 해석)

  • Hong, Seokmoo;Choi, Yong Chan;Eom, Seong-Uk;Kim, Hong Lae;Hyun, Hong Chul
    • Transactions of the KSME C: Technology and Education
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    • v.3 no.1
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    • pp.37-44
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    • 2015
  • In this paper dynamic deformation of lower hinge of refrigerator is simulated using dynamic finite element analysis while refrigerator is being dropped. The flow stress curves considering velocity dependency of hinge and lower packing material are determined through bending test and compression test at several dropping speeds. The determined material properties and flow stress from reverse engineering were used as input data for refrigerator's drop test using a dynamic finite element analysis software LS-DYNA. Additionally the result between CAE and 3D deformation measurement from real refrigerator drop test are compared and the result shows that the proposed analysis model is very useful to design lower hinge and lower packing endurable to the impulsive drop impact.

Investigation on the Effect of Laser Peening Variables on Welding Residual Stress Mitigation Using Dynamic Finite Element Analysis (동적 유한요소 해석을 통한 용접 잔류응력 이완에 미치는 레이저 피닝 변수의 영향 고찰)

  • Kim, Jong-Sung
    • Proceedings of the KWS Conference
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    • 2010.05a
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    • pp.84-92
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    • 2010
  • 현재 가동 중인 몇몇 가압 경수로 원전 안전 1등급 설비의 이종금속 용접부는 일차수응력부식균열(PWSCC : Primary Stress Corrosion Cracking) 발생의 세가지 조건(민감 재질, 부식 환경, 인장응력)을 동시에 충족하고 있다. 즉, 이종금속 용접부는 PWSCC에 민감한 재질인 Alloy 600 계열 합금으로 제작 또는 용접되어 있으며 고온 수화학 부식 환경 하에 놓여있다. 아울러 오스테나이트 스테인리스 강의 예민화 예방을 위한 용접 후열처리 미실시로 높은 인장 용접 잔류응력이 작용하고 있다. 이러한 이종금속 용접부의 특성상 PWSCC가 발생할 잠재성이 있을 뿐만 아니라 국내외적으로 Alloy 600 계열 합금으로 제작 및 용접된 가압 경수로 원전 안전 1등급 설비의 이종금속 용접부에 실제 PWSCC가 발생된 사례들이 다수 보고되고 있다. 운전 환경 및 재질 변화 없이 PWSCC 발생을 예방하기 위해서는 인장 잔류응력을 이완시켜 낮은 인장 또는 압축 응력화하여야 한다. 이러한 인장 잔류응력 이완방법들로는 PWOL(Pre-emptive Weld Overlay), 레이저 피닝(Laser Peening), MSIP(Mechanical Stress Improvement Process), 워터 제트 피닝(Water Jet Peening), IHSI(Induction Heating Stress Improvement) 방법들이 있는데 공정 시간이 짧고 열 에너지 원이 필요 없으며 전체적인 소성 변형을 야기시키지 않는 레이저 피닝을 본 연구의 대상 방법으로 한다. 본 연구에서는 동적 유한요소 해석을 통해 용접 잔류응력을 이완시키는 레이저 피닝의 효과를 검증하고 용접 잔류응력에 미치는 레이저 피닝 변수의 영향을 고찰하고자 한다. 내부 보수용접이 수행된 경수로 원전 가압기 노즐 이종금속 용접부에 레이저 피닝을 적용한 경우에 대해 상용 유한요소 해석 프로그램인 ABAQUS를 이용하여 동적 유한요소해석을 수행한 결과, 고온 수화학 일차수와 접하는 Alloy 600 계열 합금 내면에서의 인장 잔류응력이 상당히 이완됨을 확인하였다. 또한, 최대충격 압력이 증가할수록, 충격압력 지속시간이 증가할수록, 레이저 스팟 직경이 증가할수록 내표면 인장 잔류응력 이완 정도는 감소하나 이완되는 영역의 깊이는 증가함을 알 수 있다. 또한, 레이저 피닝 방향이 잔류응력 이완에 미치는 영향은 미미함을 알 수 있다.

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Simplified Nonlinear Dynamic Progressive Collapse Analysis of Welded Steel Moment Frames Using Collapse Spectrum (붕괴스펙트럼을 활용한 용접철골모멘트골조의 비선형 동적 연쇄붕괴 근사해석)

  • Lee, Cheol Ho;Kim, Seon Woong;Lee, Kyung Koo;Han, Kyu Hong
    • Journal of Korean Society of Steel Construction
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    • v.21 no.3
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    • pp.267-275
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    • 2009
  • This paper presents the behavior of column-removed double-span beams in welded steel moment frames and proposes a simplified nonlinear dynamic analysis method for the preliminary evaluation of progressive collapse potential. The nonlinear finite element analysis and the associated analytical study showed that the column gravity load and the beam span-to-depth ratio govern the maximum dynamic deformation demand of the double-span beams. Based on these results, the concept of a collapse spectrum, which describes the relationship between the gravity load parameter and the maximum chord rotation of the double-span beams, was newly proposed. A procedure for the application of the collapse spectrum to multi-story welded steel moment frames was then suggested. The inelastic dynamic finite element analysis results showed that the proposed method gives satisfactory prediction of the nonlinear progressive collapse behavior of welded steel moment frames.

Impact Response Behaviors of Laminated Composite Plates Subjected to the Transversely Impact of a Steel Ball (강구에 의한 횡방향 충격을 받는 적층복합판의 충격 응답 거동)

  • 김문생;김남식;박승범;백인환
    • Journal of Ocean Engineering and Technology
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    • v.7 no.2
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    • pp.44-56
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    • 1993
  • The purpose of this paper is to analyze the impact response behaviors of glass/epoxy laminated composite plates subjected to the transversely impact of a steel ball. For this purpose, dynamic finite element analysis based on the higher-order shear defomation plate theory is used to compute the contact forces, rebound velocity of a steel ball, and dynamic strain response histories. And low-velocity and high-velocity impact experiments were conducted to compare the results and compute the wave propagation velocities. The results obtained from impact experiments are in good agreement with those of dynamic finite element analysis. Also the wave propagation velocities obtained from high-velocity impact experiments and wave propagation theory agree well, and wave velocities were higher in the smaller radius of steel ball.

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Static/Dynamic Finite Element Analysis of Lightweight Suspension Part Fabricated by Application of phase Change Process (상변환 응용 경량 Suspension 부품의 정적/동적 유한요소해석)

  • 이정우;신현기;강충길
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2002.05a
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    • pp.848-851
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    • 2002
  • In the field of automobile industry, lightweight problems are very important in terms of reducing fuel and protecting environment. To satisfy these demands, the attempt to substitute aluminum automobile components for cast steel part has been actively carried out. To fabricate the aluminum automobile suspension part that has the same mechanical properties with cast steel part, design conditions such as shape and dimension of part shall be established. Therefore in this study, shape and dimension conditions of suspension part were proposed. Aluminum automobile suspension part was fabricated by semi-solid die-casting process under the obtained design conditions. Moreover to evaluate the possibility of application to the automobile component, stress and fatigue analysis were performed by using ABAQUS S/W and compared with those of conventional automobile suspension part.

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