• Title, Summary, Keyword: FEM

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Simulation of Dynamic Interaction Between Maglev and Guideway using FEM (FEM을 이용한 자기부상열차/궤도 동적 상호작용 시뮬레이션)

  • Han Hyung-Suk;Kim Dong-Sung;Lee Jong-Min;Kang Heung-Sik
    • Proceedings of the KSR Conference
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    • pp.363-368
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    • 2004
  • Maglev vehicles, which are levitated and propelled by electromagnets, often run on elevated guideways comprised of steel, aluminum and concrete. Therefore, an analysis of the dynamic interaction between the Maglev vehicle and the guideway is needed in the design of the critical speed, ride, controller design and weight reduction of the guideway. This study introduces a dynamic interaction simulation technique that applies FEM. The proposed method uses FEM to model the elevated guideway and the Maglev vehicle, which is different from conventional studies. Because the proposed method uses FEM, it is useful to calculate the deformation of the elevated guideway, the dynamic stress, and the motion of the vehicle. By applying the proposed method to an urban transit Maglev vehicle, UTM01, the dynamic response is simulated according to velocity increase and can be reviewed again. From the result of the study, we concluded that FEM simulation of the dynamic interaction between the maglev vehicle and the guideway is possible.

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An adaptive X-FEM and its application to shape optimization (적응 확장 유한요소기법과 형상최적설계로의 응용)

  • Yu, Yong-Gyun;Huh, Jae-Sung;Tezuka, Akira;Kwak, Byung-Man
    • Proceedings of the KSME Conference
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    • pp.538-543
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    • 2007
  • A procedure is proposed to generate optimal grid with minimal user intervention while keeping a prescribed level of accuracy, using an adaptive X-FEM and applied to shape optimization. In spite of various advantages of X-FEM, however, there are several obstacles for practical applications. Because of using a uniform background mesh and additional degree of freedoms for enrichment, an X-FEM is usually computationally more expensive than traditional finite element method. Furthermore, there are often accuracy problems. For an automatic procedure of optimal mesh generation, an h-adaptive scheme and a posteriori error estimation obtained by a post-processing process are utilized. The procedure is shown by 2-D shape optimization examples.

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A study on Mechanical Performance Evaluation of Cement Paste Using Foaming Agent by Micro FEM Analysis (Micro FEM 해석에 의한 기포제 혼입 시멘트 페이스트의 역학적 성능 평가에 관한 연구)

  • Kim, Bo-Seok;Woo, Young-Je;Lee, Han-Seung
    • Proceedings of the Korean Institute of Building Construction Conference
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    • pp.55-56
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    • 2015
  • This study is corroborated as a fundamental resource to develop structural lightweight paste containing silica fume as a part of cement. Paste using foaming agent is generated much foam and decreased density of paste. This study is measured at 0.8% of foaming agent dosage but over 0.8% of foaming agent dosage raise density of paste because of interconnection with foam. Also, FEM analysis using SEM image is confirmed correspondence of between Elastic modulus of experiment and FEM analysis.

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Studies on the Cooling Performance of Front End Module for Pedestrian Protection (보행자 보호용 프론트 엔드 모듈(FEM)의 냉각성능에 관한 연구)

  • Shin, Yoon-Hyuk;Kim, Sung-Chul
    • Transactions of the Korean Society of Automotive Engineers
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    • v.20 no.6
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    • pp.67-72
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    • 2012
  • Novel Front End Module(FEM) with improved pedestrian protection is very important to reduce the severity of pedestrian injury. The FEM needs to have enough space from hood to absorb the energy from any pedestrian collision. In this study, the cooling performance of the FEM to cool the engine was investigated under 25% height reduction. The results indicated that the cooling performance analysis was about 86% level compared to that of the conventional FEM. Also, good qualitative agreement between CFD predictions and experimental measurements was found. This FEM needs the cooling performance enhancement for changed air flow path at the frontal part of vehicle. Therefore, we showed an improved performance using air guide setup and shape modification under the high load condition.

Application of computational technologies to R/C structural analysis

  • Hara, Takashi
    • Computers and Concrete
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    • v.8 no.1
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    • pp.97-110
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    • 2011
  • In this paper, FEM procedure is applied to the static and dynamic analyses of R/C structures. Simple R/C shell structure is solved by using FEM procedures and the experimental evaluations are performed to represent the applicability of FEM procedure to R/C structures. Also, R/C columns are analyzed numerically and experimentally. On the basis of these results, FEM procedures are applied to the R/C cooling tower structures assembled by huge R/C shell structure and a lot of discrete R/C columns. In this analysis, the parallel computing procedures are introduced into these analyses to reduce the computational effort. The dynamic performances of R/C cooling tower are also solved by the application of parallel computations as well. From the numerical analyses, the conventional FEM procedures combined with computational technologies enables us to design the huge R/C structures statically and dynamically.

A Study on a Composite Laminate Pull-through Joint

  • Kwon, Jeong-Sik;Kim, Jin-Sung;Seo, Bum-Kyung;Lee, Soo-Yong
    • International Journal of Aeronautical and Space Sciences
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    • v.18 no.1
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    • pp.63-69
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    • 2017
  • In this paper, composite laminate pull-through resistance was analyzed using the FEM method and compared with test results. 2D and 3D simplified FEM models, a nonlinear analysis, and a progressive failure analysis utilizing three composite laminate failure theories Maximum Stress, Maximum Strain, and Tsai-Wu were used to predict the FEM results with the test results. The load and boundary conditions of the test were applied to the FEM to simulate the test. A composite laminate pull-through test (ASTM D7332 Proc. B) was designed with a special fixture to collect more precise data. The test results were compared with the FEM analysis results.

A Study on the Improvement of the Steel Pylon Base Design Using Nonlinear FEM Analysis (비선형 FEM 해석을 이용한 기존 강재 주탑기부 설계의 개선방안 연구)

  • Jung, Soo-Hyung;Park, Sung-Woo
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.18 no.1
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    • pp.19-30
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    • 2014
  • In this study nonlinear FEM analysis for steel pylon base of a cable supported bridge is performed in order to compare the results of Akashi-Kaikyo bridge's design specification established in 1970. Due to convenience of its application, the Akashi grand bridge's design specification has been applied to the base design of cable stayed bridges. It has been using linear spring in order to model prestressed high tensioned bars between steel pylon bottom plates and the base concrete. However, the results of nonlinear FEM analysis revealed that the Akashi-Kaikyo bridge's design specification has various problems in the analysis of the steel pylon base. And the steel pylon base has various complex members connecting with each other, and it is main member to resist against the wind load or the earthquake load. Therefore, the nonlinear FEM analysis has to be conducted in order to predict the behavior of steel pylon base exactly. Also, the nonlinear FEM analysis is more reasonable for the load and resistant factor design.

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.

Improved Vibration Vector Intensity Field for FEM and Experimental Vibrating Plate Using Streamlines Visualization (유선 가시화를 이용한 FEM과 실험에 의한 진동판에 대한 개선된 진동 벡터 인텐시티장)

  • Fawazi, Noor;Jeong, Jae-Eun;Oh, Jae-Eung
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.22 no.8
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    • pp.777-783
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    • 2012
  • Vibration intensity has been used to identify the location of a vibration source in a vibrating system. By using vectors representation, the source of the power flow and the vibration energy transmission paths can be revealed. However, due to the large surface area of a plate-like structure, clear transmission paths cannot be achieved using the vectors representation. Experimentally, for a large surface object, the number of measured points will also be increased. This requires a lot of time for measurement. In this study, streamlines representation is used to clearly indicate the power flow transmission paths at all surface plate for FEM and experiment. To clearly improve the vibration intensity transmission paths, streamlines representation from experimental works and FEM computations are compared. Improved transmission paths visualization for both FEM and experiment are shown in comparison to conventional vectors representation. These streamlines visualization is useful to clearly identify vibration source and detail energy transmission paths especially for large surface plate-like structures. Not only that, this visualization does not need many measured point either for experiment or FEM analysis.

Forced Vibration Analysis of Plate Structures Using Finite Element-Transfer Stiffness Coefficient Method (유한요소-전달강성계수법을 이용한 평판 구조물의 강제진동해석)

  • 최명수
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.13 no.2
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    • pp.99-107
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    • 2003
  • The finite element method(FEM) is the most widely used and powerful method for structural analysis. In general, in order to analyze complex and large structures, we have used the FEM. However, it is necessary to use a large amount of computer memory and computation time for solving accurately by the FEM the dynamic problem of a system with many degree-of-freedom, because the FEM has to deal with very large matrices in this case. Therefore, it was very difficult to analyze the vibration for plate structures with a large number of degrees of freedom by the FEM on a personal computer. For overcoming this disadvantage of the FEM without the loss of the accuracy, the finite element-transfer stiffness coefficient method(FE-TSCM) was developed. The concept of the FE-TSCM is based on the combination of modeling technique in the FEM and the transfer technique in the transfer stiffness coefficient method(TSCM). The merit of the FE-TSCM is to take the advantages of both methods, that is, the convenience of the modeling in the FEM and the computation efficiency of the TSCM. In this paper, the forced vibration analysis algorithm of plate structures is formulated by the FE-TSCM. In order to illustrate the accuracy and the efficiency of the FE-TSCM, results of frequency response analysis for a rectangular plate, which was adopted as a computational model, were compared with those by the modal analysis method and the direct analysis method which are based on the FEM.