• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 추계학술대회논문집
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• pp.708-713
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• 2000

Finite element analysis is frequently used to get dynamic characteristics of complex structures. Since the results often show differences from experimentally measured ones, updating of finite element models is performed to make the FE results agree with measured ones. Among several model updating methods, one is to use frequency response function data. This paper investigates characteristics of the model updating method using simulated and experimental data for a cantilever beam. Damping effect is included in FE models, and FRFs for rotational displacements are calculated from FRFs for translational displacements using interpolation.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2009년도 정기 학술대회
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• pp.425-428
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• 2009

This paper presents a sensitivity-based finite element (FE)-model update procedure for prestressed concrete (PSC) girder bridge model using vibration test results. Firstly, the stiffness parameters of the structure such as flexural rigidity of concrete and flexural rigidity of tendon are chosen as updating parameters. Next, the numerical frequencies of first two bending modes are calculated using a three-dimensional FE model which is established for the PSC girder. Then, the corresponding experimental frequencies which are obtained from forced vibration tests are selected. In order to perform the model update, the eigensensitivity-based method is employed. Finally, the effect of prestress-loss on the stiffness parameters is evaluated.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.1696-1701
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• 2007

This paper presents a micro-mechanical model of ductile fracture for the API X65 steel using the Gurson-Tvergaard-Needleman (GTN) model. Experimental tests and FE damage simulations using the GTN model are performed for smooth and notched tensile bars, from which the parameters in the GTN model are calibrated. As application, the developed GTN model is applied to simulate small-sized, single-edge-cracked tensile and bend bars, via three-dimensional FE damage analyses. Comparison of FE damage analysis results with experimental test data shows overall good agreements.

• International Journal of Railway
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• 제8권2호
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• pp.42-45
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• 2015

Alkali-silica reaction (ASR) is a chemical reaction in concrete that alkalis in cement react with reactive silica in aggregate in the presence of water. When ASR takes place, it produces gels that absorb water and expand. Swelling of ASR gels can damage concrete and cause cracking and volume expansion in concrete structure. In this paper, mechanical consequences of ASR on concrete are simulated by a finite element (FE) analysis. An FE model of concrete is built. The evolution of concrete mechanical properties subjected to ASR is achieved by FE analyses. The constitutive model of concrete is attained via the FE analysis. A case study is used to demonstrate the proposed method. The simulated results using the proposed model are in good agreement with the observations of concrete with ASR reported in the literature. The results can be used for a basic research to enhance durability of concrete slab tracks and concrete railway sleepers.

• 한국생산제조학회지
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• 제22권6호
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• pp.931-936
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• 2013

Recently, the use of large-electron-beam polishing for polishing complex metal surfaces has been proposed. In this study, the temperature induced by a large electron beam was predicted using the heat transfer theory. A finite element (FE) model of a continuous wave (CW) electron beam was constructed assuming Gaussian distribution. The temperature distribution and melting depth of an SUS304 sample were predicted by changing electron-beam polishing process parameters such as energy density and beam velocity. The results obtained using the developed FE model were compared with experimental results for verifying the melting depth prediction capability of the developed FE model.

• 대한토목학회논문집
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• 제32권4C호
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• pp.159-167
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• 2012

본 연구는 실내 모형말뚝 재하실험과 유한요소해석을 통해 모형말뚝 선단부 주변 흙의 변형률 거동을 비교 분석하였다. 모형말뚝의 하중을 모사하기 위해 LCM(load control method) 기법과 DCM(displacement control method) 기법을 소개하고, 이 중 수치해석에 타당한 기법을 제안하였다. 유한요소해석에 있어서 말뚝의 미끄럼 거동을 모사하기 위해 기존과는 달리 두 가지 경계면 요소를 사용하여 모형실험 결과와 비교하였다. 본 연구를 통해 비연관 흐름의 정도(degree of non-associated flow)가 수치해석 값 수렴에 중요한 요소임을 알 수 있었다. 또한 수치해석에 있어 대칭인 최대전단변형률 분포를 얻기 위해서는 새로이 개선된 유한요소망(finite element mesh)의 도입이 필요함을 알 수 있었다.

• The Journal of Advanced Prosthodontics
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• 제13권6호
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• pp.396-407
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• 2021

PURPOSE. Zirconia has exceptional biocompatibility and good mechanical properties in clinical situations. However, finite element analysis (FEA) studies on the biomechanical stability of two-piece zirconia implant systems are limited. Therefore, the aim of this study was to compare the biomechanical properties of the two-piece zirconia and titanium implants using FEA. MATERIALS AND METHODS. Two groups of finite element (FE) models, the zirconia (Zircon) and titanium (Titan) models, were generated for the exam. Oblique (175 N) and vertical (175 N) loads were applied to the FE model generated for FEA simulation, and the stress levels and distributions were investigated. RESULTS. In oblique loading, von Mises stress values were the highest in the abutment of the Zircon model. The von Mises stress values of the Titan model for the abutment screw and implant fixture were slightly higher than those of the Zircon model. Minimum principal stress in the cortical bone was higher in the Titan model than Zircon model under oblique and vertical loading. Under both vertical and oblique loads, stress concentrations in the implant components and bone occurred in the same area. Because the material itself has high stiffness and elastic modulus, the Zircon model exhibited a higher von Mises stress value in the abutments than the Titan model, but at a level lower than the fracture strength of the material. CONCLUSION. Owing to the good esthetics and stress controllability of the Zircon model, it can be considered for clinical use.

• Advances in Computational Design
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• 제2권4호
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• pp.333-348
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• 2017

Inspections of ancient metallic bridges have illustrated fatigue cracking in riveted connections. This paper presents a comparison between two alternative finite element (FE) models proposed to predict the fatigue strength of a single shear and single rivet connection. The first model is based on solid finite elements as well as on contact elements, to simulate contact between the components of the connection. The second model is built using shell finite elements in order to model the plates of the riveted connection. Fatigue life predictions are carried out for the shear splice, integrating both crack initiation and crack propagation lives, resulting from the two alternative FE models. Global fatigue results, taking into account several clamping stresses on rivet, are compared with available experimental results. Proposed comparisons between predictions and experimental data illustrated that the proposed two-stage model yields consistent results.

• Structural Engineering and Mechanics
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• 제13권3호
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• pp.261-276
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• 2002

A novel, 6-node, two-dimensional mixed finite element (FE) model has been developed to analyze laminated composite beams by using the minimum potential energy principle. The model has been formulated by considering four degrees of freedom (two displacement components u, w and two transverse stress components ${\sigma}_z$, $\tau_{xz}$) per node. The transverse stress components have been invoked as nodal degrees of freedom by using the fundamental elasticity equations. Thus, the present mixed finite element model not only ensures the continuity of transverse stress and displacement fields through the thickness of the laminated beams but also maintains the fundamental elasticity relationship between the components of stress, strain and displacement fields throughout the elastic continuum. This is an important feature of the present formulation, which has not been observed in various mixed formulations available in the literature. Results obtained from the model have been shown to be in excellent agreement with the elasticity solutions for thin as well as thick laminated composite beams. A few results for a cross-ply beam under fixed support conditions are also presented.

• 소성∙가공
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• 제33권1호
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• pp.50-54
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• 2024

In this paper, the process of extruding Cu-10Fe alloy using a finite element analysis (FEA) was theoretically analyzed. To achieve this, the dependence of strain rate and temperature of the alloy required for the extrusion process was secured by utilizing databases for Cu and Fe and the KHL model. For microstructure analysis, FE-SEM with EDS was used to distinguish the phases present in Cu-10Fe alloy. The mechanical characteristics of Cu-10Fe alloy were secured using the results of fitting the mechanical properties of Copper and Steel from the Deform database to the KHL model. The deformation behavior within the alloy during hot extrusion was analyzed, providing insights into effective stress, effective strain, effective strain rate, and temperature. It was observed that the strain distribution was non-uniform. These research findings contribute to an improved understanding of the hot extrusion process of Cu-10Fe alloy and can aid in predicting the mechanical properties of the material.