• Design & Manufacturing
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• 제7권1호
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• pp.34-39
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• 2013

The finite element method(FEM) presents some limitations when the mesh becomes highly distorted. For analysis of metal forming processes with large deformation, the conventional finite element method usually requires several remeshing operations due to severe mesh distortion. The new computational method developed in the recent years, usually designated by meshfree method, offers an attractive approach to avoid those time-consuming remeshing efforts. This new method uses a set of points to represent the problem domain with no need of an additional mesh. Also this new generation of computational method provides a higher rate of convergence than that of the conventional finite element methods. One of the promising applications of meshfree methods is the adaptive refinement for problems having multi-scale nature. In this study, an adaptive node generation procedure is proposed and also to illustrate the efficiency of proposed method, several numerical examples are presented.

• 동력기계공학회지
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• 제19권1호
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• pp.38-44
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• 2015

Various finite elements have been studied and developed to analyze a variety of structures in the finite element method(FEM). The transfer stiffness coefficient method(TSCM) is an effective algorithm for structural analysis but the structures which can be applied were limited. In this paper, a computational algorithm for the structural analysis of axisymmetric conical shells under axisymmetric loading is formulated using the finite element-transfer stiffness coefficient method(FE-TSCM). The basic concept of FE-TSCM is the combination of the modeling technique of FEM and the transfer technique of TSCM. The FE-TSCM has all the advantages of both FEM and TSCM. After carrying out the structural analysis of axisymmetric conical shells using FEM, FE-TSCM, and analytical method we compare the computational results of FE-TSCM with those of the other methods in terms of computational accuracy.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1993년도 추계학술대회 논문집
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• pp.206-211
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• 1993

The explicit scheme for finite element analysis of sheet metal forming problems has been widely used for providing practical solution since it improves the convergency problem,memory size and computational time especially for the case of complicated geometry and large element number. In the present work, a basic formulation for rigid-plastic explicit finite element analysis of plain strain sheet metal forming problems has been proposed. The effect of some basic parameters involved in the dynamic analysis has been studied in detail. A direct trial-and-error method is introduced to treat contact and friction. In order to show the validity and effectiveness of the proposed explicit scheme, computation are carried out for cylindrical punch stretching and the computational results are compared with those by the implicit scheme as well as with a commercial code. The proposed rigid-plastic explicit element method can be used as a robust and efficient computational method for analysis of sheet method forming.

• 한국전산구조공학회논문집
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• 제19권1호
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• pp.39-46
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• 2006

본 연구는 파 해석에 있어서 공간-시간 분할 개념을 도입하여 켈러킨 방법으로 해석하였다. 공간-시간 유한요소법은 오직 공간에 대해서만 분할하는 일반적인 유한요소법보다 간편하다. 비교적 큰 시간간격에 대해서 공간과 시간을 동시에 분할하는 방법을 제시하며 가중잔차법이 공간-시간 영역에서 유한요소 정식화에 이용되었다. 큰 시간 간격으로 인하여 문제의 해가 발산하는 경우가 동적인 문제에서 흔히 발생한다. 이러한 결점을 보완한 사각형 공간-시간 요소를 취하여 문제를 해석하고 해의 안정에 대해 기술하였다. 다수의 수치해석을 통하여 이 방법이 효과적 임을 알 수 있었다.

• 한국광학회:학술대회논문집
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• 한국광학회 1989년도 제4회 파동 및 레이저 학술발표회 4th Conference on Waves and lasers 논문집 - 한국광학회
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• pp.157-160
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• 1989

The most serious difficulty in using the finite element method is the appearance of the so-called spurious, nonphysical modes. We have proposed the finite element formulation of the variational expression in the three-component magnetic field based on Galerkin's method. In this approach, the divergence relation H is satisfied and spurious modes does not appear and finite-element solutions agree with the exact solutions.

• 동력기계공학회지
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• 제16권6호
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• pp.45-51
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• 2012

In this paper, the algorithm for the static analysis of an axisymmetric cylindrical shell by using the finite element-transfer stiffness coefficient method (FE-TSCM) is suggested. TE-TSCM combining both the modeling procedure of the finite element method (FEM) and the transfer procedure of the transfer stiffness coefficient method (TSCM) has the advantages of FEM and TSCM. After computational programs are made by both FE-TSCM and FEM for the stress analysis of the axisymmetric cylindrical shell, we compare the numerical results by FE-TSCM with those of FEM for two computational models in order to confirm the trust of FE-TSCM.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계학술대회논문집
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• pp.247-250
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• 2005

Underwater acoustic transducers are widely used for SONAR application, whose important design parameters are shapes, materials, dimensions and supporting structures. Practical design method of transducers consists of manufacturing, experiments and modifications so that It requires much time and expenses. In this study, an analytical method was developed for the Tonpilz type transducers using the commercial finite element analysis code ATILA which can solve the electro-mechanical coupling Problems. A finite element model was established including the transducer elements such as ceramic stack, head mass, tall mass, tensile bolt, and molding layers. The proposed model was verified and modified by comparing the in-air and in-water test results of prototypes. The developed analysis method will be effectively used for the sensitivity analysis of design parameters in transducer design process.

• 대한기계학회논문집A
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• 제32권1호
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• pp.54-62
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• 2008

In this paper the fretting wear of press-fitted specimens subjected to a cyclic bending load was simulated using finite element analysis and numerical method. The amount of microslip and contact variable at press-fitted and bending load condition in a press-fitted shaft was analysed by applying finite element method. With the finite element analysis result, a numerical approach was applied to predict fretting wear based on modified Archard's equation and updating the change of contact pressure caused by local wear with influence function method. The predicted wear profiles of press-fitted specimens at the contact edge were compared with the experimental results obtained by rotating bending fatigue tests. It is shown that the depth of fretting wear by repeated slip between shaft and boss reaches the maximum value at the contact edge. The initial surface profile is continuously changed by the wear at the contact edge, and then the corresponding contact variables are redistributed. The work establishes a basis for numerical simulation of fretting wear on press fits.

• 대한기계학회논문집A
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• 제20권7호
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• pp.2067-2077
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• 1996

In adaptive finite element analysis, r- and h-methods are generally used on the basis of a discretization error estimator. In this paper, an rh-method is proposed as a new adaptive method which can improve the adaptivity performance by using both of them. This suggested rh-method moves nodal coordinates of initially given model to adjust element discretization errors and thereafter performes the h-method tdo obtain the specified accuracy of finite element solutions. Numerical experiments for various plane problems were performed using 4-noded isoparametric quadrilateral elements. As a result, the rh-method has been shown to be an accurate and efficient adaptive analysis method to obtain as improved solution.

• 전산구조공학
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• 제11권1호
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• pp.179-190
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• 1998

두개의 케이블요소를 이용한 3차원 케이블망의 정적 비선형 유한요소해석기법을 제시한다. 먼저, 공간 트러스요소와 탄성현수선 케이블요소(elastic catenary cable element)의 접선강도행렬과 질량행렬을 유도하는 과정을 간략히 요약한다. 지점 변위를 일으키고 자중을 받는 케이블망의 초기평형 상태를 결정하기 위하여, Newton-Raphson 반복법에 근거한 하중증분법과 현수케이블요소를 적용하는 경우에 viscous damping을 고려한 dynamic relaxation법을 제시한다. 또한 초기의 정적평형상태를 기준으로 추가하중에 대한 케이블망의 정적 비선형해석을 수행한다. 지점변위와 외력을 받는 케이블 구조에 대하여 비선형해석을 수행하고, 해석결과들을 기존의 문헌의 결과와 비교, 검토하므로써 본 논문에서 제시한 이론 및 해석방법의 타당성을 입증한다.