• Title/Summary/Keyword: Element simulation

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Finite Element Analysis on the Energy Absorption Characteristics of Hybrid Structure (충격흡수용 복합부재의 에너지 흡수특성에 관한 유한요소해석)

  • 신현우
    • Transactions of the Korean Society of Automotive Engineers
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    • v.12 no.5
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    • pp.101-107
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    • 2004
  • Recently the objective of vehicle design was focused on the crash safety and the energy saving. For the energy saving vehicle structures must be light weight, but for the crash safety some energy absorbing elements must be added. In this paper hybrid structure which consists of a steel and a FRP was studied on the energy absorption characteristics under the impact load by finite element method. Test results of the other researchers were compared with that of computer simulation on this simple hybrid structure. Side rail of vehicle front structure was replaced with hybrid materials for the application of the vehicle structure. 35mph frontal crash simulation was performed with hybrid structure and with conventional steel structure. By the adoption of hybrid structure, the improvement of energy absorption characteristics and reduction of weight was observed under the frontal crash simulation.

Simulation of Charging Process in PTFE Electret (PTFE 일렉트렛트의 대전 과정 시뮬레이션)

  • Park, Geon-Ho;Kim, Sang-Jin;Sung, Nak-Jin;Bae, Duk-Kwun
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2005.05b
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    • pp.123-126
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    • 2005
  • In this study, the Thermally Stimulated Current(TSC) of corona charged PTFE is studied and the simulation of corona charging process is also calculated by Finite Element Method. The electrets which were formed by applying high voltages (DC ${\pm}5{\sim}{\pm}8$ [kV]) to PTFE, are used to measure TSC in the temperature range of $-100{\sim}+200$ [$^{\circ}C$] and then the Finite Element Method is performed to examine corona charging process using a obtained physical constants. As a result. it is confirmed that the charging negative corona is profitable as the applications are manufactured, because the time constant of negative corona is much larger than it of positive corona. And it is attempted to estimate the corona charging process in space using simulation.

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A Study on the Process Improvements of the Multi-stage Deep Drawing by the Rigid-plastic Finite Element Method (강소성 유한요소법을 이용한 다단계 디프드로잉의 공정개선에 관한 연구)

  • 전병희;민동균;김형종;김낙수
    • Transactions of Materials Processing
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    • v.3 no.4
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    • pp.440-453
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    • 1994
  • The multi-stage deep-drawing processes including normal-drawing, reverse-drawing, and re-drawing are analyzed by use of the rigid-plastic finite element method. Computational results on the punch/die loads and thickness distributions were compared with the experiments of the current drawing processes. Deep-drawing processes of the redesigned shell to improve the specific strength and stiffness were simulated with the numerical method developed. With varying several process parameters such as blank size, corner radii of tools, and clearances, the simulation results showed the improvements in reducing the forming loads. Also forming defects were found during simulation and appropriate blank size could be verified.

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Numerical study of wake structure behind a square cylinder at high Reynolds number

  • Lee, Sungsu
    • Wind and Structures
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    • v.1 no.2
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    • pp.127-144
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    • 1998
  • In this paper, the wake structures behind a square cylinder at the Reynolds number of 22,000 are simulated using the large eddy simulation, and the main features of the wake structure associated with unsteady vortex-shedding are investigated. The Smagorinsky model is used for parametrization of the subgrid scales. The finite element method with isoparametric linear elements is employed in the computations. Unsteady computations are performed using the explicit method with streamline upwind scheme for the advection term. The time integration incorporates a subcycling strategy. No-slip condition is enforced on the wall surface. A comparative study between two-and three-dimensional computations puts a stress on the three-dimensional effects in turbulent flow simulations. Simulated three-dimensional wake structures are compared with numerical and experimental results reported by other researchers. The results include time-averaged, phase-averaged flow fields and numerically visualized vortex-shedding pattern using streaklines. The results show that dynamics of the vortex-shedding phenomenon are numerically well reproduced using the present method of finite element implementation of large eddy simulation.

Improvement of the Representative Volume Element Method for 3-D Scaffold Simulation

  • Cheng Lv-Sha;Kang Hyun-Wook;Cho Dong-Woo
    • Journal of Mechanical Science and Technology
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    • v.20 no.10
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    • pp.1722-1729
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    • 2006
  • Predicting the mechanical properties of the 3-D scaffold using finite element method (FEM) simulation is important to the practical application of tissue engineering. However, the porous structure of the scaffold complicates computer simulations, and calculating scaffold models at the pore level is time-consuming. In some cases, the demands of the procedure are too high for a computer to run the standard code. To address this problem, the representative volume element (RVE) theory was introduced, but studies on RVE modeling applied to the 3-D scaffold model have not been focused. In this paper, we propose an improved FEM-based RVE modeling strategy to better predict the mechanical properties of the scaffold prior to fabrication. To improve the precision of RVE modeling, we evaluated various RVE models of newly designed 3-D scaffolds using FEM simulation. The scaffolds were then constructed using microstereolithography technology, and their mechanical properties were measured for comparison.

The Simulation of Corona Charging Process in Polytetrafluoroethylene Electret using Finite Element Method (유한요소법을 이용한 PTFE 일렉트렛트의 코로나 대전 과정 시뮬레이션)

  • 이수길;유재웅;박건호;김충혁;이준웅
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1994.05a
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    • pp.94-98
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    • 1994
  • In this study, the thermally stimulated current(TSC) of corona charged PTFE film was studied and the simulation of corona charging process was also calculated by finite element method. The electrets which were formed by appling high voltages(DC-5∼-8[kV]) to PTFE film were experimented to measure TSC in the temperature range of -100∼+200 [$^{\circ}C$] and then the finite element method was accomplished to examine corona charging process using a obtained physical constants. It is confirmed that the charging negative corona is profitable as the applications are manufactured because the time constant of negative corona is much larger than it of positive corona. And it is attempted to estimate the corona charging process in space using simulation.

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Investigation of bonding properties of Al/Cu bimetallic laminates fabricated by the asymmetric roll bonding techniques

  • Vini, Mohamad Heydari;Daneshmand, Saeed
    • Advances in Computational Design
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    • v.4 no.1
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    • pp.33-41
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    • 2019
  • In this study, 2-mm Al/Cu bimetallic laminates were produced using asymmetric roll bonding (RB) process. The asymmetric RB process was carried out with thickness reduction ratios of 10%, 20% and 30% and mismatch rolling speeds 1:1, 1:1.1 and 1:1.2, separately. For various experimental conditions, finite element simulation was used to model the deformation of bimetallic Al/Cu laminates. Specific attention was focused on the bonding strength and bonding quality of the interface between Al and Cu layers in the simulation and experiment. The optimization of mismatch rolling speed ratios was obtained for the improvement of the bond strength of bimetallic laminates during the asymmetric RB process. During the finite element simulation, the plastic strain of samples was found to reach the maximum value with a high quality bond for the samples produced with mismatch rolling speed 1:1.2. Moreover, the peeling surfaces of samples around the interface of laminates after the peeling test were studied to investigate the bonding quality by scanning electron microscopy.

Stochastic vibration analysis of functionally graded beams using artificial neural networks

  • Trinh, Minh-Chien;Jun, Hyungmin
    • Structural Engineering and Mechanics
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    • v.78 no.5
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    • pp.529-543
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    • 2021
  • Inevitable source-uncertainties in geometry configuration, boundary condition, and material properties may deviate the structural dynamics from its expected responses. This paper aims to examine the influence of these uncertainties on the vibration of functionally graded beams. Finite element procedures are presented for Timoshenko beams and utilized to generate reliable datasets. A prerequisite to the uncertainty quantification of the beam vibration using Monte Carlo simulation is generating large datasets, that require executing the numerical procedure many times leading to high computational cost. Utilizing artificial neural networks to model beam vibration can be a good approach. Initially, the optimal network for each beam configuration can be determined based on numerical performance and probabilistic criteria. Instead of executing thousands of times of the finite element procedure in stochastic analysis, these optimal networks serve as good alternatives to which the convergence of the Monte Carlo simulation, and the sensitivity and probabilistic vibration characteristics of each beam exposed to randomness are investigated. The simple procedure presented here is efficient to quantify the uncertainty of different stochastic behaviors of composite structures.

Finite Element Analysis for Forming Processes of $\OMEGA$ -Type Bellows Tubes (오메가형 벨로즈관의 성형공정을 위한 유한요소해석)

  • Lee, Junghoon;Kim, Naksoo;Jeon, Byunghee
    • Journal of the Korean Society for Precision Engineering
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    • v.14 no.10
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    • pp.85-90
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    • 1997
  • The study presents a computer-aided analysis and its design for the forming process of .OMEGA. -type bellows tubes. Finite element analysis was carried out to perform the process simulation. Bsed on the analytic results of various conditions, the forming conditions used for angled U-type bellows tubes were determined. The 3-D modeling was constructed by I-DEAS and the process simulation was constructed by PAM- STAMP. It is concluded that the difference of height between die and bellows during the forming process causes a non-uniform shape of the bellows and also influences .OMEGA. -shape. These results can be utilized for the process design.

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Influence of Modeling Errors in the Boundary Element Analysis of EEG Forward Problems upon the Solution Accuracy

  • Kim, Do-Won;Jung, Young-Jin;Im, Chang-Hwan
    • Journal of Biomedical Engineering Research
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    • v.30 no.1
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    • pp.10-17
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    • 2009
  • Accurate electroencephalography (EEG) forward calculation is of importance for the accurate estimation of neuronal electrical sources. Conventional studies concerning the EEG forward problems have investigated various factors influencing the forward solution accuracy, e.g. tissue conductivity values in head compartments, anisotropic conductivity distribution of a head model, tessellation patterns of boundary element models, the number of elements used for boundary/finite element method (BEM/FEM), and so on. In the present paper, we investigated the influence of modeling errors in the boundary element volume conductor models upon the accuracy of the EEG forward solutions. From our simulation results, we could confirm that accurate construction of boundary element models is one of the key factors in obtaining accurate EEG forward solutions from BEM. Among three boundaries (scalp, outer skull, and inner skull boundary), the solution errors originated from the modeling error in the scalp boundary were most significant. We found that the nonuniform error distribution on the scalp surface is closely related to the electrode configuration and the error distributions on the outer and inner skull boundaries have statistically meaningful similarity to the curvature distributions of the boundary surfaces. Our simulation results also demonstrated that the accumulation of small modeling errors could lead to considerable errors in the EEG source localization. It is expected that our finding can be a useful reference in generating boundary element head models.