• Title/Summary/Keyword: Finite Element Method, FEM

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Study on the Drawbead Expert Models (드로우비드 전문모델에 관한 연구)

  • 김준환
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2000.04a
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    • pp.26-29
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    • 2000
  • drawbead expert models are developed for calculating drawbead restraining force and drawbead-exit thinnings which are boundary conditions in FEM stamping simulation employing the linear multiple regression method by which the deviation of drawing characteristics between drawing test and mathematical model is minimized. In order to show the efficiency and accuracy of an expert drawbead model a finite element simulation of auto-body panel stamping is carried out. The finite element simulation shows that the expert drawbead model provides the accurate solution guarantees the stable convergence and the merit in the computation time.

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Finite element solutions of natural convection in porous media under the freezing process (동결과정을 포함한 다공층에서 자연대류에 대한 유한요소 해석)

  • Lee, Moon-Hee;Choi, Chong-Wook;Seo, Suk-Jin;Park, Chan-Guk
    • Proceedings of the KSME Conference
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    • 2000.04b
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    • pp.51-56
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    • 2000
  • The Finite Element Solutions Is reported on solid-liquid phase change in porous media with natural convection including freezing. The model is based on volume averaged transport equations, while phase change is assumed to occur over a small temperature range. The FEM (Finite Element Method) algorithm used in this study is 3-step time-splitting method which requires much less execution time and computer storage the velocity-pressure integrated method and the penalty method. And the explicit Lax-Wendroff scheme is applied to nonlinear convective term in the energy equation. For natural convection including melting and solidification the numerical results show reasonable agreement with FDM (Finite Difference Method) results.

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Effect of Process Parameters on Cylindrical Open Die Forging (FEM을 이용한 원형 자유단조의 공정인자 영향에 관한 연구)

  • 최성기;김원태;천명식;문영훈
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2003.05a
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    • pp.221-224
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    • 2003
  • In the open die forging process, it is difficult to optimize process parameters such as die shape, initial ingot size, feeding pitch, rotation angle and other process parameters in the operational environments. Therefore in this study, 3D finite element analysis has been performed to obtain optimal process condition for open die forging process. FEM analyses at various feeding pitches and rotation angles provide process conditions to make round bar having precise dimensional accuracy.

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Spectral Element Method for the Dynamic Behaviors of Plate (스펙트럴요소법을 이용한 평판의 동적거동해석)

  • 이상희;이준근;이우식
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 1996.04a
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    • pp.328-334
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    • 1996
  • Finite Element Method(FEM) is the most popularly used method in analyzing the dynamic behaviors of structures. But unless the number of finite elements is large enough, the results from FEM are somewhat different from exact analytical solutions, especially at high frequency range. On the other hand, as the Spectral Element Method(SEM) deals directly with the governing equations of structures, the results from this method cannot but be exact regardless of any frequency range. However, despite two dimensional structures are more general, the SEM has been applied only to the analysis of one dimensional structures so far. In this paper, therefore, new methodologies are introduced to analyze the two dimensional plate using SEM. The results from this new method are compared with the exact analytical solutions by letting the two dimensional plate be one dimensional one and showed the dynamic responses of two dimensional plate by including various waves propagated into x-direction.

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Analytical and higher order finite element hybrid approach for an efficient simulation of ultrasonic guided waves I: 2D-analysis

  • Vivar-Perez, Juan M.;Duczek, Sascha;Gabbert, Ulrich
    • Smart Structures and Systems
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    • v.13 no.4
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    • pp.587-614
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    • 2014
  • In recent years the interest in online monitoring of lightweight structures with ultrasonic guided waves is steadily growing. Especially the aircraft industry is a driving force in the development of structural health monitoring (SHM) systems. In order to optimally design SHM systems powerful and efficient numerical simulation tools to predict the behaviour of ultrasonic elastic waves in thin-walled structures are required. It has been shown that in real industrial applications, such as airplane wings or fuselages, conventional linear and quadratic pure displacement finite elements commonly used to model ultrasonic elastic waves quickly reach their limits. The required mesh density, to obtain good quality solutions, results in enormous computational costs when solving the wave propagation problem in the time domain. To resolve this problem different possibilities are available. Analytical methods and higher order finite element method approaches (HO-FEM), like p-FEM, spectral elements, spectral analysis and isogeometric analysis, are among them. Although analytical approaches offer fast and accurate results, they are limited to rather simple geometries. On the other hand, the application of higher order finite element schemes is a computationally demanding task. The drawbacks of both methods can be circumvented if regions of complex geometry are modelled using a HO-FEM approach while the response of the remaining structure is computed utilizing an analytical approach. The objective of the paper is to present an efficient method to couple different HO-FEM schemes with an analytical description of an undisturbed region. Using this hybrid formulation the numerical effort can be drastically reduced. The functionality of the proposed scheme is demonstrated by studying the propagation of ultrasonic guided waves in plates, excited by a piezoelectric patch actuator. The actuator is modelled utilizing higher order coupled field finite elements, whereas the homogenous, isotropic plate is described analytically. The results of this "semi-analytical" approach highlight the opportunities to reduce the numerical effort if closed-form solutions are partially available.

Finite Element Method Analysis of Eddy Current Array Probe According to Defects Variation of Steam Generator (배열와전류프로브를 이용한 증기발생기 세관의 결함 변화에 따른 유한요소해석)

  • Kim, Ji-Ho;Lee, Hyang-Beom
    • 한국정보통신설비학회:학술대회논문집
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    • 2009.08a
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    • pp.54-58
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    • 2009
  • In this paper, the ECT(eddy current testing) signal analysis of eddy current array probe for inspection of SG(steam generator) tube in NPP(nuclear power plant) using electromagnetic FEM(finite element method) was performed. To obtain the electromagnetic characteristics of probes, the governing equation was derived from Maxwell's equation, and the problem was solved by using the 3-dimensional FEM. The types of defects were FBH(flat bottomed hole) and OD groove, Spiral groove, natural defects(pitting, SCC, multiple SCC, wear). The depth of FBH defects were 20%, 40%, 60%, 80%, 100 of SG tube thickness, and it was assumed that the defects were located on the tube outside. And the operation frequency of 100kHz, 300kHz and 400kHz were used. Material of specimen was Inconel 600 which is usually used for SG tubes in NPP. The signal difference could be observed according to the variation of size and depth on FBH defects and operation frequencies. The results in this paper can be helpful when the ECT signals from EC array probe are evaluated and analyzed.

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Effects of piezoelectric material on the performance of Tonpilz transducer using finite element method (Tonpilz 트랜스듀서의 성능에 미치는 압전소재의 영향)

  • Seo, Jin-Won;Choi, Kyoon;Lee, Ho-Yong
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.26 no.4
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    • pp.139-144
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    • 2016
  • Effects of the shape and size of the piezoelectric materials on the performance of tonpilz transducers were studied with a computer simulation using a finite element method (FEM). The diameter and height of the donut-shaped piezoelectric ceramics head mass were changed as variables. And the effect of the stack number was also investigated. Finally, if the piezoelectric ceramics were changed to a piezoelectric single crystal having high piezoelectric constants, how the performances especially, the output power and the TVR transmittance were affected was simulated by FEM. As a result, the output of transducer could be increased to 10 times of PZT-4 with replacement of relaxor single crystal of the same size.

Finite Element Method Analysis of Safety Valve (안전밸브의 유한요소해석)

  • Lee, Jong-Sun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.13 no.9
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    • pp.3864-3868
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    • 2012
  • In this paper, a safety valve was modeled by using 3-dimensional designing program, Solidsworks after it was dismantled and measured. And 3-dimensional finite element analysis code, ANSYS was used to FEM analysis. Stress, strain and deformation were obtained when some amount of pressure was applied to the safety valve through FEM analysis.

A Finite Element Model for Bipolar Resistive Random Access Memory

  • Kim, Kwanyong;Lee, Kwangseok;Lee, Keun-Ho;Park, Young-Kwan;Choi, Woo Young
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.14 no.3
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    • pp.268-273
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    • 2014
  • The forming, reset and set operation of bipolar resistive random access memory (RRAM) have been predicted by using a finite element (FE) model which includes interface effects. To the best of our knowledge, our bipolar RRAM model is applicable to realistic cell structure optimization because our model is based on the FE method (FEM) unlike precedent models.