• 한국정밀공학회지
• /
• 제13권3호
• /
• pp.80-93
• /
• 1996

A 2-dimensional FEM/GEM program was developed under the plane strain assumption using linear line elements for analyzing stretch/draw forming operations of an arbitrarily shaped draw-die. FEM formulation adopted a new algorithm for solving force equilibrium as well as non-penetration condition simultaneously. Also, a rigid-viscoplastic material model with Hill's normal anisotropic yield condition and rate-sensitive hardening law is assumed, along with the Coulomb friction law in the contact regions. For the case of numerical divergence at nearly final forming stages, geometric force equilibrium method(GEM) is also introduced. The developed program was tested by simulating the forming processes of cylindrical punch/open die, and the drawing processes of automotive oilpan and hood inner panel in order to verify the usefulness and validity of FEM/GEM formulation. The numerical simulation verified the validity and robustness of developed program.

• 한국복합재료학회:학술대회논문집
• /
• 한국복합재료학회 2005년도 춘계학술발표대회 논문집
• /
• pp.176-179
• /
• 2005

Rotating annular disks are widely used in data storage devices such as CDs, DVDs(digital versatile disks), and HDs(hard disks) as well as in traditional industrial machines like sawing machines, turbines, brake disks. The exact stress distribution of rotating polar orthotropic disk is derived by solving directly the equilibrium equation instead of using stress function. Stress distributions for typical GFRP and CFRP disks are presented in addition to polycarbonate disk. The results show that the application of CFRP to rotating disk can increase the maximum allowable rotating speed but this may not be applicable to GFRP disk.

• 대한기계학회논문집A
• /
• 제20권6호
• /
• pp.1819-1826
• /
• 1996

This paper present the claculating method of optimum correction mass within permissible vibration linits for ratating machinery in two-plane field balancing. Basic technique of this method is based on influence coefficient method, and grphic vector composition that the resultant of two influence vectors obtained by trial mass have to be equilibrium with initial vibration vector in the each correction plane. Genetic algorithm which is a search algorithm based on the mechanism of natural selection and natural genetics is sued for vector composition, and SUMT method is used to objective function which seeks optimum correction mass for balancing a rotor.

• Structural Engineering and Mechanics
• /
• 제8권4호
• /
• pp.343-360
• /
• 1999

This work applies a structural analysis method based on an analytical solution from the Fourier series which transforms a half-range cosine expansion into a static solution involving plated structures. Two sub-matrices of in-plane and plate-bending problems are also formulated and coupled with the prescribed boundary conditions for these variables, thereby providing a convenient basis for a numerical solution. In addition, the plate connection are introduced by describing the connection between common boundary continuity and equilibrium. Moreover, a simple computation scheme is proposed. Numerical results are then compared with finite element results, demonstrating the numerical scheme's versatility and accuracy.

• 전산구조공학
• /
• 제9권1호
• /
• pp.133-139
• /
• 1996

이 논문은 원호형 곡선보의 면외 자유진동에 관한 연구이다. 곡선보 요소의 동적 평형방정식에 Timoshenko 이론을 적용하여 원호형 곡선보의 자유진동을 지배하는 상미분방정식을 유도하고 이를 수치해석하여 고유진동수를 산출할 수 있는 개략해법 중 하나인 수치해석기법을 개발하였다. 수치해석기법에서 미분방정식의 수치적분은 Runge-Kutta method를 이용하였고, 고유진동수의 결정은 Regular-Falsi method를 이용하였다. 실제 수치해석예에서는 회전-회전보, 고정-고정보에 대하여 시행하고 고유진동수에 미치는 무차원 변수들의 영향을 고찰하였다.

• 대한기계학회논문집
• /
• 제15권5호
• /
• pp.1530-1537
• /
• 1991

본 연구에서는 반무한 직선 계면균열의 상하면에 임의로 분포하는 어떠한 하 중에 대해서도 그 해석이 가능한 그린함수(Green's function)를 구하고자 한다. 이 를 위하여 반무한 직선 계면균열상의 임의의 한 점에 평면 집중하중이 작용하는 문제 와 비평면 집중전단하중이 작용하는 문제를 각각 택하였고, 이때 계면균열의 선단은 열려있다고 가정하였다. 이 문제를 풀므로써 균열선단부근의 응력성분을 결정하고 이로부터 그린함수의 의미를 지니는 응력강도계수에 대한 폐형해를 얻었다.

• Structural Engineering and Mechanics
• /
• 제57권6호
• /
• pp.1107-1124
• /
• 2016

Consistent finite strain Plate constitutive relations are derived based on a hyperelastic formulation for an isotropic material. Plate equilibrium equations under finite strain are derived following a static kinematic approach. Three Euler angles and four shear angles, based on Timoshenko beam theory, represent the kinematics of the deformations in the plate cross section. The Green deformation tensor has been expressed in term of a deformation tensor associated with the deformation and stretches of an embedded plate element. Buckling formulation includes the in-plane axial deformation prior to buckling and transverse as well as in-plane shear deformations. Numerical results for a simply supported thick plate under uni-axial compression force are presented.

• 한국안전학회지
• /
• 제15권2호
• /
• pp.103-110
• /
• 2000

This paper deal with the stability evaluation and suggestion of progressive failure slope in biotite granite area of Andong. Based on geological site investigation and field test, stability analysis of slope was performed in conjunction with limit equilibrium methods and stereographic projection. Additionally, initial design and construction procedure was critically evaluated. Series of the slope stability analysis reveals the detection of local wedge and plane failure under the current slope condition. It is additionally appeared that a certain synthetic behavior of circle and plane failure exists on the right spot where the overall failure's going in progress. In order to construct more stable slope based on the suitability for the real state of the slope circumstances, this study issues a solution to eliminate the primary factors which cause the instability, by means of the grade of weathering and RMR classification of rock mass.

• Structural Engineering and Mechanics
• /
• 제65권3호
• /
• pp.275-290
• /
• 2018

The hygrothermal stresses in sandwich plate with composite faces due to through the thickness gradient temperature and (or) moisture content are investigated. The layer-wise theory is employed for formulation of the problem. The formulation is derived for sandwich plate with general layer stacking, subjected to uniform and non-uniform temperature and moisture content through the thickness of the plate. The governing equations are solved for free edge conditions and 3D stresses are investigated. The out of plane stresses are obtained by equilibrium equations of elasticity and by the constitutive law and the results for especial case are compared with the predictions of a 3D finite element solution in order to study the accuracy of results. The three-dimensional stresses especially the free edge effect on the distribution of the stresses is studied in various sandwich plates and the effect of uniform and non-uniform thermal and hygroscopic loading is investigated.

• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 1996년도 봄 학술발표회 논문집
• /
• pp.182-189
• /
• 1996

The focus of this study is on the problem of the design of structure of undetermined topology. This problem has been regarded as being the most challenging of structural optimization problems, because of the difficulty of allowing topology to change. Conventional approaches break down when element sizes approach to zero, due to stiffness matrix singularity. In this study, a novel nonlinear Programming formulation of the topology Problem is developed and examined. Its main feature is the ability to account for topology variation through zero element sizes. Stiffness matrix singularity is avoided by embedding the equilibrium equations as equality constraints in the optimization problem. Although the formulation is general, two dimensional plane elasticity examples are presented. The design problem is to find minimum weight of a plane structure of fixed geometry but variable topology, subject to constraints on stress and displacement. Variables are thicknesses of finite elements, and are permitted to assume zero sizes. The examples demonstrate that the formulation is effective for finding at least a locally minimal weight.