• Title, Summary, Keyword: FEM

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Study of FEM with integrated antenna (안테나를 집적한 FEM에 대한 연구)

  • Kim Jun-Kyu;Kang Sung-Won;Cheon Chang-Yul
    • 한국정보통신설비학회:학술대회논문집
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    • pp.189-192
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    • 2006
  • 본 논문에서는 안테나와 미국 PCS대역(1.85GHz-1.99GHz) FEM(Front End Module)을 결합하여 하나의 패키지로 구현하는 것을 연구하였다. FEM의 크기를 고려하여 안테나의 크기를 작게 만들고 단말기에 내장하기 위해 PIFA(Planar Inverted F Antenna)형식의 안테나를 선택하였다. 안테나의 지지를 위해 비유전율 2의 캐리어를 사용하였고, 안테나와 FEM간의 상호 간섭을 막기 위해 도체로 차폐시켰다. 유한요소법(Finite Element Method)로 모의 실험을 하여 안테나를 설계하고 실제 제작하여 모의 실험결과와 비교하였다. 제작한 안테나를 FEM과 결합, 기판을 제작하여 FEM의 이득을 측정하였다.

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Iterative coupling of precise integration FEM and TD-BEM for elastodynamic analysis

  • Lei, Weidong;Liu, Chun;Qin, Xiaofei;Chen, Rui
    • Structural Engineering and Mechanics
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    • v.67 no.4
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    • pp.317-326
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    • 2018
  • The iterative decomposition coupling formulation of the precise integration finite element method (FEM) and the time domain boundary element method (TD-BEM) is presented for elstodynamic problems. In the formulation, the FEM node and the BEM node are not required to be coincident on the common interface between FEM and BEM sub-domains, therefore, the FEM and BEM are independently discretized. The force and displacement converting matrices are used to transfer data between FEM and BEM nodes on the common interface between the FEM and BEM sub-domains, to renew the nodal variables in the process of the iterations for the un-coincident FEM node and BEM node. The iterative coupling formulation for elastodynamics in current paper is of high modeling accuracy, due to the semi-analytical solution incorporated in the precise integration finite element method. The decomposition coupling formulation for elastodynamics is verified by examples of a cantilever bar under a Heaviside-type force and a harmonic load.

FEM Modeling Automation of Machine Tools Structure (공작기계 구조물의 전산 모델링 자동화)

  • Lee, Chan-Hong;Ha, Tae-Ho;Lee, Jae-Hak
    • Journal of the Korean Society for Precision Engineering
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    • v.29 no.10
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    • pp.1043-1049
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    • 2012
  • The FEM analysis of machine tools is the general analysis process to evaluate machine performance in the industry for a long time. Despite advances in FEM software, because of difficult simplicity of CAD drawing, little experience of joints stiffness modeling and troublesome manual contact area divide for bindings, the industry designers think the FEM analysis is still an area of FEM analysis expert. In this paper, the automation of modeling process with simplicity of drawing, modeling of joints and contact area divide is aimed at easy FEM analysis to enlarge utilization of a virtual machine tools. In order to verify the effects of modeling automation, a slant bed type model with tilting table is analyzed. The results show FEM modeling automation method only needed 45 minutes to complete the whole modeling process, while manual modeling method requires almost one month with 8200 calculations for coordinate transformations and stiffness data input.

Comparative Study of LEM and SSR-FEM on Stability of Reinforced Soil Slope (보강토사면의 안정성에 대한 LEM과 SSR-FEM의 비교연구)

  • Kim, Young-Min;Kang, Seong-Gwi
    • Journal of the Korean Geosynthetics Society
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    • v.8 no.1
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    • pp.11-18
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    • 2009
  • This paper presents a comparative study of reinforced soil slope by using LEM and SSR-FEM. Current analysis methods for reinforced soil wall are based on LEM. SSR-FEM assumes a reduction of soil strength by a factor to reach a critical state prior to failure based on continuum mechanics. In this study the comparisons are concerned with the factor of safety and the potential failure surface in reinforced soil wall. We investigated the stability of the reinforced soil wall with a slope of $60^{\circ}$ by LEM and SSR-FEM. The comparisons indicated good performance of the SSR-FEM on stability analysis of reinforce soil wall.

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Optimization technique using the eXtended FEM (X-FEM 을 이용한 최적설계 기법)

  • Huh, Jae-Sung;Akira, Tezuka;Kwak, Byung-Man
    • Proceedings of the KSME Conference
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    • pp.1870-1875
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    • 2003
  • Optimization has been used in many engineering problems and must be one of the essential components during design process now. It is the process of maximizing the performance called an objective function of a system while satisfying some constraints, so finite element method is generally required in order to obtain these values during optimization. However, there are some difficulties to obtain them by means of FEM, where the changes of design variables cause the distortion and the regeneration of mesh that may result in inaccuracy and inefficiency. In order to overcome this problem, this paper proposed an alternative that the eXtended FEM introduced and developed by Ted Belytschko was applied to the optimization process because the key points of the X-FEM lie in that the discontinuity can be represented independently on the mesh by a function called in an enrichment function.

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X-FEM Based Shape Design Sensitivity Analysis of Crack Propagation Problems (균열진전 문제의 X-FEM 기반 형상 설계민감도 해석)

  • Moon, Min-Yeong;Ahn, Seung-Ho;Cho, Seon-Ho
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.697-700
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    • 2011
  • 본 논문에서는 X-FEM을 사용하여 혼합모드 하중 상태에서의 이차원 선형탄성체의 균열문제에 대한 형상 설계민감도 해석을 수행하였다. X-FEM이란 균열과 같은 특수한 해를 근사하는 방법으로써, 확장함수를 도입하여 FEM의 한계를 극복하는 방법론이다. X-FEM 하에서 해를 근사하는 데 쓰이는 확장함수들은 불연속성과 특이성을 포함하고 있어 물리적 영역에 의존한다. 이는 설계민감도 해석을 수행하는 과정에서 그러한 의존성을 고려해주는 것이 필요하다. 따라서 본 논문에서는 X-FEM 기반의 형상 설계민감도 해석해를 제안하고자 한다. 식의 유도는 전 미분 공식에 기초하고 있으며, 형상함수의 설계변분에 대한 의존성에 관한 항을 추가시켰다. 또한, 균열 주위의 국부적인 공간에서의 확장된 자유도에 설계속도를 가한다. 이에 대한 몇 가지 수치 예제를 통하여 개발된 방법론의 타당성을 확인하였다.

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Deformation analysis of Tool and Tool holder for Micromachining by FEM (FEM을 이용한 Micromachining용 Tool 및 Tool holder의 변형해석)

  • Min, Kyung-Tak;Jang, Ho-Su
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.9 no.1
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    • pp.87-92
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    • 2010
  • Micromachining technology using a ultra-precision micromachining system is widely applied in the fields of optics, biotechnology and analytical chemistry, etc. specially in microfabrication of fresnel lens, light guide panels of TFT-LED and PDP ribs with micro-patterns, machining errors have an effect on the performance of those products. The deflection of tool and tool holder is known to be one of the very important factors that is due to machining errors in micromachining. The deflections of diamond tool and tool holder used in micro-grooving are analysed by FEM. We analysed by FEM. With an linearity valuation of FEM, deflection of tool and tool holder is calculated by using the data of cutting force which is acquired from micro-V groove machining experiments in micromachining system.

Analysis of Signal Propagation in Nonlinear Optical Fiber using SS-FEM with Sparse Matrix (희귀행렬 SS-FEM에 의한 비선형 광섬유의 전송신호 해석)

  • Jeong, Baek-Ho;Lee, Ho-Jun
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.49 no.1
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    • pp.52-58
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    • 2000
  • Signal propagation in nonlinear optical fiber is analyzed numerically by using SS-FEM (Split-Step Finite Element Method). By adopting cubic element function in FEM, soliton equation of which exact solution was well known, has been solved. Also, accuracy of numerical results and computing times are compared with those of Fourier method, and we have found that solution obtained from using FEM was very relatively accurate. Especially, to reduce CPU time in matrix computation in each step, the matrix imposed by the boundary condition is approximated as a sparse matrix. As a result, computation time was shortened even with the same or better accuracy when compared to those of the conventional FEM and Fourier method.

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Study on Torque Analysis of Micro-Electromagnetic Clutch by Using FEM (FEM을 이용한 Micro-Electromagnetic Clutch 토크해석)

  • Piao Changhao;Cho Chongdu;Kim Myunggu;Pan Qiang
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.54 no.2
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    • pp.60-65
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    • 2005
  • This study tries to analyzes the static friction torque that generated in a micro-electromagnetic clutch by using FEM. For the purpose of design change and optimization of the micro-electromagnetic clutch, the static friction torque prediction is very important. We construct the axi symmetric FEM model for analyze the static friction torque and the real material properties are substituted to the FEM model. For a test, predicted static friction torque is compared with experimental one to discuss the rationality of torque analysis process. The analytical result agrees well to experimental data. explaining the validity of the mathematical process and FEM model.

Tuning Fork Analysis using FEM and BEM (FEM과 BEM을 사용한 소리굽쇠 분석)

  • Jarng, Soon-Suck;Lee, Je-Hyeong;Park, Yeun-Young
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.401.2-401
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    • 2002
  • An unconstrained tuning fork with a 3-D model has been numerically analyzed by Finite Element Method (FEM) and Boundary Element Method (BEM). The first three natural frequencies were calculated by the FEM modal analysis. Then the change of the modal frequencies was examined with the variation of the tuning fork length and width. (omitted)

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