• Journal of Advanced Marine Engineering and Technology
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• 제18권4호
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• pp.69-76
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• 1994

Thermal elasto-plastic analysis of axi-symmetric body by the finite element method is presented in this paper for analyzing the process of upset forming of circular section extruded bar. The example of calculation for upset forming of Nimonic extruded bar is also presented. It is shown that remeshing of quadrilateral finite element is necessary because the very highly distorted element by plastic deformation disturbs the calculation. Calculated values for nodal points in new mesh are obtained from nodal points of old mesh by linear interpolation method. The experimental results are compared with calculated values. The appearance of upsetupset forming obtained by experimental method is very similar to that obtained by calculations. So, it is proved that the thermal elasto-plastic analysis of axi-symmetric body by the finite element method is very useful for finding the optimum upsetting condition.

• 소성∙가공
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• 제12권6호
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• pp.550-557
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• 2003

In this study, a web-based system was developed by utilizing finite element method and virtual system designed using Virtual Reality Modeling Language (VRML). The simulation program for axi-symetric sheet forming is developed using finite flement method. The developed system consists of two modules, client module and server module. The client module was developed by using Active-X control. The input data for FEM calculation is transferred to the server module by using communication protocol. Then sever module performs several successive processes: input data generation, forming simulation, conversion of results to VRML format. After that, the results from the simulation can be visualized on the web browser in client computer. Besides, client module offers the capability to control and navigate on virtual forming machine and calculated result. By using this system simulation result can be investigated more realistically in virtual environment including forming machine.

• 한국정밀공학회지
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• 제13권9호
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• pp.165-173
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• 1996

The dimensional accuracy of a final product is mainly affected by elastic die deformation during the forging and elastic recovery after the ejection in cold forging process. The investigations on elastic recovery are not so much as those of elastic die deformation. The elastic recovery can be determined by using the elastic-plalstic finite element analysis, but, this method has some limits such as poor conver- gence and long computational time, etc. In this paper, a theoretical analysis for predicting the elastic recovery of a final product in axi-symmetric forging process by using the rigid-plastic finite element method is presented. The rigid-plastic finite element analysis of a cold forward extrusion process involving loading, ejecting process is accomplished by rigid-plastic FE code, DEFORM. The effect of elastic die deformation on the final product dimenmsion is also considered. The calculated elastic recovery is compared is compared with the analysis result of elastic-plastic FE code. ABAQUS.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.127-127
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• 2010

This study describes the optimal design of shield to improve the insulation performance of vacuum interrupter(VI). Axi-symmetric finite element routine including floating boundary condition for shields was applied to analyze electric potential and field distribution in VI. A ($\mu-\lambda$) Evolution Strategy(ES) is employed as optimization method. Three design variables of shield are selected for minimizing the maximum electric field strength in VI. Finally, optimal solution for shield is obtained and compared with the result of the prototype.

• 한국음향학회지
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• 제13권2호
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• pp.60-67
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• 1994

본 논문은 두 편으로 연결된 논문의 첫 논문으로 무한음향 매질내의 축대칭음향 변환기 음향특성 해석을 위한 유한요소법과 하이브리드형 무한요소법의 결합 알고리즘을 제시하고 이를 이용한 음향변환기의 방사 임피던스, 지향성 및 압전자간의 결합 효과에 대한 수치해석 결과를 제시하였다. 두번째 논문에서는 첫논문의 결과를 기초로 광대역 배역 변환기를 설계하고 설계된 변환가의 음향특성을 해석하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.102-104
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• 2001

This paper presents a numerical analysis of the eddy current testing for pipe with axi-symmetric defect according to frequency changes using the finite element method(FEM). The defects used in this analysis are inner and outer axi-symmetric type. In order to obtain the behaviors of the signals by changing the frequency, the defects with different depths are modeled and analyzed using FEM. It is important to choose proper frequency because of the effect of skin depth in eddy current testing. This paper describes signal characteristics of each defects as frequency is changed.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 B
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• pp.748-750
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• 2001

This paper describes numerical analysis of eddy current testing for tube with axi-symmetric defect using boundary element method. In this ECT(Eddy Current Testing) numerical analysis. BEM and FEM are used to compare their characteristics and results of ECT, respectively BEM is easier than FEM to design geometrically complex domain because in case of BEM, domain is divided into segments or elements, but in case of FEM, domain is divided into small finite triangular or quadrilateral elements. For this reason asymmetry defect is used for this BE numerical analysis. As a result, the similar result can be obtained through both numerical analyses, and BEM can be applied to the numerical analysis of ECT.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제23회 추계학술대회 논문집
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• pp.278-281
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• 2004

본 논문의 목적은 KSLV-1 KM 축소형 연소관의 변형을 예측할 수 있는 효과적인 해석방법을 제시하는 것을 목적으로 하며, 내압을 받는 F/W 복합재 연소관에 대한 구조해석과 실험을 수행하였다. 효과적인 연소관의 해석을 위해 돔 무위 기하학적 비선형성을 고려한 유한요소법의 3차원 적층 축대칭요소(layered axi-symmetric solid element)에 적용하였다. 유한요소 해석은 전처리 프로그램(HC2004)을 이용 연소관 돔 부위에서의 기하학적 비선형성을 고려하여 ANSYS로 해석을 수행 하였으며, 그 결과 전처리 시간 및 계산 소요시간이 짧았으며, 수압실험 결과 값과 비교, 검토하였다.

• 한국콘텐츠학회논문지
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• 제13권2호
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• pp.505-511
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• 2013

경사진 지형을 갖는 축대칭 지형에 적용이 가능한 경계처리기법을 개발하였다. 섬 지형의 경우 복잡한 지형으로 인하여 유한요소모형을 사용하여 파의 변형을 해석하는 것이 좋지만 해수와 접하는 섬의 단면이 연직이 아닌 경우에는 수심이 0이 되어 경계면을 적절하게 처리하기 어렵다는 단점이 있다. 본 연구에서는 장파에 대한 해석해를 활용하여 임의의 경사진 경계면에 적용가능한 경계처리기법을 개발하였다. 이를 위해 지배방정식으로 완경사 방정식을 사용하였으며 계산 영역을 해석해 영역과 수치해 영역으로 구분하여 해석해 영역에 기존의 해석해를 적용한 후 수치해와 결합하여 모델을 완성하였다. 유도된 해는 기존의 해석해와 비교하여 그 타당성을 검증하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 B
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• pp.831-833
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• 2000

In this paper, a numerical analysis algorithm of eddy current testing(ECT) for heat exchanger tube with axi-symmetric defects using finite element method(FEM) is presented. In the ECT FEM analysis, we used trianglular and rectangular elements for exact signal of ECT for variable shape of defects. This paper presents a systematic and efficient numerical analysis algorithm for ECT. We employ the LU decomposition and Cholesky method for solving the system matrix. This numerical analysis algorithm is effectively applied to heat exchanger tube with defects.