• 제목/요약/키워드: 유한 대형요소

검색결과 266건 처리시간 0.018초

극후판 Box Column의 Corner Joint 용접시 발생하는 Lamella Tearing에 관한 연구 (A Study of Lamella Tearing being Produced by Corner Joint Welding in Box Column of Ultra Thick Plate)

  • 방한서;김성주;김종명;장웅성;권영섭
    • 대한조선학회논문집
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    • 제36권4호
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    • pp.95-104
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    • 1999
  • 강 구조물의 대형화에 기인하여 대형 해양구조물, 선박, 교량 및 고층 구조물에서의 극후판의 사용이 지속적으로 증가하고 있으며, 이런 경향은 앞으로도 계속될 것으로 생각된다. 그러나, 극후판을 사용하여 구조물을 시공할 때, 층상균열의 발생이 보고되고 있으며 이것은 극후판의 두께방향 중심부를 따라 분포하는 황, 인등의 불순 개재물 및 용접에 기인하여 발생하는 구속 잔류응력에 의하여 발생하는 것으로 알려져 있다. 연속 주조공법에 의하여 제조되는 극후판의 제조공정의 특성상, 층상균열의 발생은 회피하기가 현실적으로 어려우며, 따라서, 본 논문에서는 강구조물의 층상균열 발생의 감소 방안으로서, 금속학적 측면보다는 용접강도 측면에서 유한요소법에 기초한 전산 프로그램을 사용하여 최적 개선부형상 및 용접순서를 선정하고자 한다.

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양방향 재하시험결과를 활용한 바렛말뚝의 하중전이특성 평가 (Evaluation of Load Transfer Characteristics of Barrette Pile Based on Bi-directional Loading Tests)

  • 박성완;임대성
    • 대한토목학회논문집
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    • 제29권2C호
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    • pp.41-49
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    • 2009
  • 구조물의 대형화와 재료비의 증가로 인해 다수의 기성말뚝을 대체할 수 있는 대형 현장타설말뚝의 사용이 증가하고 있다. 특히, 지하연속벽공법이 적용된 현장의 기초시공에 따른 시공성 및 경제성을 향상시키거나 토사층이 깊게 분포한 경우 공벽의 안정성을 확보하기 위한 기초형식으로 바렛말뚝의 사용이 증가하고 있는 실정이다. 본 논문에서는 국내 4개 현장을 대상으로 바렛말뚝을 시공하고 양방향 재하시험을 실시하여 말뚝의 지지력 및 침하특성을 고찰하였다. 또한 하중전이분석을 통하여 주면마찰력의 평가를 위한 ${\beta}$값을 분석하여 비교 평가하였고 3차원 유한요소해석을 통하여 양방향재하시험에 따른 경계면 효과와 하중-침하특성을 살펴보았다.

대형마찰용접을 이용한 로타샤프트 제조공정개발 (Process Development of Rotor Shaft using a Large Friction Welding)

  • 정호승;조종래;이낙규;박희천;최성규
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 2007년도 춘계학술대회 논문집
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    • pp.401-404
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    • 2007
  • Inertia welding is a solid-state welding process in which butt welds in materials are made in bar and in ring form at the joint face, and energy required for welding is obtained from a rotating flywheel. The stored energy is converted to frictional heat at the interface under axial load. The quality of the welded joint depends on many parameters, including axial force, initial revolution speed and energy, amount of upset, working time, and residual stresses in the joint. Inertia welding was conducted to make the large rotor shaft for low speed marine diesel engine, alloy steel for shaft of 140mm. Due to different material characteristics, such as, thermal conductivity and flow stress, on the two sides of the weld interface, modeling is crucial in determining the optimal weld geometry and parameters. FE simulation was performed by the commercial code DEFORM-2D. A good agreement between the predicted and actual welded shape is observed. It is expected that modeling will significantly reduce the number of experimental trials needed to determine the weld parameters.

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대형 해상풍력발전용 필라멘트 와인딩 복합재 타워의 동적 특성에 관한 연구 (Dynamic Characteristics Analysis of Filament-wound Composite Towers for Large Scale Offshore Wind-Turbine)

  • 한정영;홍철현;정재훈;문병영
    • 한국유체기계학회 논문집
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    • 제15권4호
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    • pp.55-60
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    • 2012
  • The purpose of this study is to investigate the buckling load of filament-wound composite towers for large scale wind-turbine using finite element method(FEM). To define material properties, we used both the effective property method and the stacking properties method. The effective properties method is to assume that composite consists of one ply. The stacking properties method is to assume that composite consists of some stacked plies. First, linear buckling analysis of the tower, filament-wounded with angles of [${\pm}30$] was carried out by two methods for composite material properties, the stacking method and the effective method. and FE analysis was performed for the composite towers according to filament winding angles of [${\pm}30$], [${\pm}45$], [${\pm}60$]. FE analysis results using the stacking properties of the composite were in good agreement with the results by the effective properties. The difference between FEM results by material properties methods was approximately 0~2.3% in buckling Analysis and approximately 0~0.6% in modal analysis. And above the angle of [${\pm}60$], there was a little change of buckling load.

온도분포 해석 해와 유한요소법을 이용한 대형 강판의 용접변형 해석 (Analysis of Welding Distortion of Large Steel Plate by Using Analytical Solution of Temperature Distribution and Finite Element Method)

  • 홍성빈;배강열;양영수
    • Journal of Welding and Joining
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    • 제32권4호
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    • pp.69-74
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    • 2014
  • Welding distortions of large steel structures had mainly been estimated with some simplified formula obtained by lots of experience and numerical analyses for small steel structures. However, the large structures would have different characteristics of distortion with welding because of their own stiffness coming from the size itself. Therefore, in order to find some measures for preventing welding distortion of large structure, it is requite in advance to precisely analysis thermal stress and distortion during welding of the structure. Numerical analysis for larger structure has been known to take large amount of calculation time and have a poor convergency problem during the thermo-elasto-plastic calculation. In this study, a hybrid method is proposed to analysis the thermal stress and distortion of a large steel plate with the finite element analysis by incorporating with temperature distribution of the plate calculated by an analytical solution. The proposed method revealed that the thermo-mechanical analysis for welding of the large structure could be performed with a good convergence and produced precise results with much reduced time consumption.

실험계획법을 이용한 대형트럭 조종성 향상을 위한 설계인자 최적조합에 관한 연구 (A Study on Optimal Combination of Design Parameters for Improving Handling Performance of a Large Truck Using Design of Experiments)

  • 문일동;이동환;오재윤
    • 대한기계학회논문집A
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    • 제28권6호
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    • pp.799-806
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    • 2004
  • This paper presents a scheme for finding an optimal combination of design parameters affecting on the handling performance of a large truck using design of experiments. The average of the sum of peak-to-peak roll angles at the first and second part of the double lane is used as an objective function for design of experiments. Six design parameters are selected from all possible parameters affecting on the handling performance. The table of orthogonal arrays is made by 27 times simulations. A computational model of a large truck is developed by MSC/NASTRAN and MSC/ADAMS, and verified the reliability of it with the results of vehicle tests performed in a double lane change course. It is used for the simulations. Analyses of variance and factor effect of the table of orthogonal arrays are performed. This paper proposes an optimal combination of those six design parameters for improving the handling performance of the large truck.

대형 풍력 발전용 필라멘트 와인딩 복합재 타워의 고유 진동수 해석에 관한 연구 (Modal Analysis of Filament-wound Composite Towers for Large Scale Wind-Turbine)

  • 홍철현
    • 한국해양공학회지
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    • 제25권2호
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    • pp.73-78
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    • 2011
  • The purpose of this study was to investigate the natural frequency of filament-wound composite towers for large scale wind-turbines using the finite element method (FEM). To define the material properties, we used both the effective property method and the stacking properties method. The effective properties method assumes that a composite consists of one ply. The stacking properties method assumes that a composite consists of several stacked plies. First, a modal analysis of the tower, filament-wound with angles of $[{\pm}30]$, was carried out using the two methods for composite material properties, the stacking method and effective method. Then, an FE analysis was performed for composite towers using filament winding angles of $[{\pm}30]$, $[{\pm}45]$, and $[{\pm}60]$. The FE analysis results using the stacking properties of the composite were in good agreement with the results from the effective properties method. The difference between the FEM and material properties methods was approximately 0~0.6%

대형 압력용기 제작을 위한 9Ni-4Co-0.3C 강의 드로잉공정 설계에 관한 연구 (Design of drawing process of 9Ni-4Co-0.3C steel to make a large pressure vessel)

  • 홍진태;이석렬;김경진;양동열;이경훈;최문선
    • 한국정밀공학회지
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    • 제22권12호
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    • pp.93-99
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    • 2005
  • In this work, computer-aided process design is carried out to develop an optimal preform of a pressure vessel. Knowledge-based rules are employed to design the preform, and they are formulated using the handbooks of plasticity theories. In the FE-analysis, a commercial finite element code, ABAQUS was employed. Axisymmetric deep drawing of a hemisphere-bottomed cup has been analyzed fur various combinations of die design parameters. The length of the land of die, the clearance between punch and die and the clearance between the blank holder and die are optimized to minimize the forming load. The results of the simulations are verified with the experiments which are scaled down to one tenth of the actual size.

대형트럭 프레임의 결합방법이 조종성능에 미치는 영향 (The Effects of the Mounted Method of Frame of a Large Truck on Handling Performance)

  • 문일동;오재윤;오석형
    • 한국정밀공학회지
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    • 제21권8호
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    • pp.112-119
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    • 2004
  • This paper develops a computer model of a cabover type large truck for estimating the effects of the mounted method of frame on handling performance. The computer model considers two mounted methods of frame; flange mounted and web mounted. Frame is modeled by finite elements using MSC/NASTRAN in order to consider the flexibility of frame. The reliability of the developed computer model is verified by comparing the actual vehicle test results with the simulation results. The actual vehicle test is performed in a double lane change course, and lateral acceleration, yaw rate, and roll angle are measured. To estimate the effects of the mounted method of frame on handling performance, simulations are performed with the flange mounted and web mounted frame. Simulation results show that the web mounted frame's variations of roll angle, lateral acceleration, and yaw rate are larger than the flange mounted frame's variations, especially in the high test velocity and the second part of the double lane course. Also, simulation results show that the web mounted frame's tendencies of roll angle, lateral acceleration, and yaw rate advance the flange mounted frame's tendencies, especially in the high test velocity and the second part of the double lane course.

마찰용접을 이용한 대형선박 터보챠저용 이종 로타샤프트 개발 (Development of Large Rotor Shaft for Marine Turbo Charger Using Friction Welding with Dissimilar Materials)

  • 문광일;전종원;정호승;조종래;최성규
    • 한국정밀공학회지
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    • 제33권4호
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    • pp.257-264
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    • 2016
  • Solid state joining techniques are increasingly applied in a wide range of industrial applications. Friction welding is a solid state welding technique that is used to join similar or dissimilar materials. In this study, friction welding was applied to rotor shaft composed of a disk and a shaft. The disk and shaft were manufactured by hot forging and rolling, respectively. The aim of the study was to predict the structural characteristics during hot forging and friction welding process for rotor shaft of turbo charger. The structural characteristics were determined by heat input and heat affected zone (HAZ) during a short cycle time. Thus, transient FE analysis for hot forging and friction welding was based on heat transfer. The results were used to predict structural characteristics during hot forging and friction welding processes. The prototype of rotor shaft was manufactured by the result-based process parameters.