• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.16 no.7 s.112
• /
• pp.712-719
• /
• 2006

This paper is concerned with the comparison of substructure synthesis methods based on global and local coordinates. The substructure synthesis methods based on the global coordinates were first proposed for the dynamic analysis of complex structure and the substructure synthesis method based on the local coordinates was proposed to solve the dynamic problem of tree-like structure. However, the conceptual difference between two methods in solving the dynamic problem has never been explained. In this paper, a structure consisting of two beams is considered to show the conceptual difference of two methods. The dynamic formulation shows the characteristics and differences of two methods explicitly. The procedure for choosing proper substructure modes in each method is also explained in detail. In addition, the advantage of the substructure synthesis method based on the local coordinate system is discussed based on the numerical example. Numerical examples show how two methods are applied to the addressed problem.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.14 no.4
• /
• pp.810-817
• /
• 1990

본 연구에서는 국부질점 좌표계(natural convected coordinate system)를 이 용하여 변형을 묘사하는 대변형을 고려한 탄소성 증분수식을 유도하고 또 이에 해당하 는 유한 요소 방정식을 구하였다. 국부 질점 좌표계를 사용함으로써 변형도 성분이 나 구성 방정식의 성분들에 대한 좌표 변환 과정을 생략하도록 한다. 재료는 수직 이방성으로 가정하였다. 이 수식화의 타당성을 검증하기 위하여 원형 격막의 정수압 벌징을 해석하고 해석 결과는 실험 결과와 이미 발표된 실험 및 해석 결과와 비교하여 타당성을 검증하였다.

• Computational Structural Engineering
• /
• v.9 no.1
• /
• pp.33-45
• /
• 1996

A general stiffener element which includes transverse shear deformation is formulated using the p-version finite element method. Hierarchic C/sup o/-shape functions, derived from Integrals of Legendre polynomials, are used to define the assembled stiffness matrix of the stiffener with respect to the local reference frame is transformed to the plate reference system by applying the appropriate transformation matrices in order to insure compatibility of displacements at the junction of the stiffener and plate. The transformation matrices which account for the orientation and the eccentricity effects of the stiffener with respect to the plate reference axes are used to find local behavior at the junction of the stiffener and the relative contributions of the plate and stiffener to the strength of the composite system. The results obtained by the p-version finite element method are comared with the results in literatures, especially those by the h-version finite element analysis program, MICROFEAP-II.

• Journal of Power System Engineering
• /
• v.7 no.4
• /
• pp.49-54
• /
• 2003

스프링은 가장 널리 이용되어지고 있는 기계요소이다. 본 논문에서는 원추형 코일스프링의 강성을 구하기 위하여, 빔요소를 이용한 유한요소법을 사용하였다. 가상일의 법칙을 이용하였고, 코일스프링의 하중벡터를 압축 분포하중으로 대체하였다. 하중의 증가에 의한 절점에서의 변위는 유한요소법를 이용하여 계산하였다. 단계법으로 결점의 변위를 중첩하여 전체 강성행렬을 구하였다. 유한요소법에 의한 해석치는 실험치와 잘 일치하였다. 본 논문에서 제시한 프로그램을 사용하여, 스프링 강성과 응력을 예측할 수 있을 것으로 사료된다.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2011.04a
• /
• pp.231-234
• /
• 2011

본 논문은 교량의 안전진단을 위한 각 부재의 명명체계에 따라 직선형 교량모델의 각 부재에 대한 솔리드 객체의 고유번호를 일괄적으로 부여하기 위한 방법론을 제시한다. 개발된 방법론은 크게 3 단계의 프로세스로 이루어진다. 먼저, 부재의 종류별로 구분된 레이어로부터 각 부재에 대한 솔리드 객체의 도심을 추출하고, 이를 시점과 종점으로 이루어진 교축방향을 축으로 한 국부좌표계에 대해 변환한다. 이후 교축방향으로 정렬되는 객체를 식별하여 그룹핑하고 이를 교축 및 교축의 직각방향으로 순서로 정렬한다. 마지막으로 각 그룹 내 세그먼트들을 교축방향으로 정렬한다. 개발된 방법론에 따른 시범 응용모듈을 개발하였으며, 트러스 구조와 서로 다른 모델 좌표계를 가진 시범 교량모델을 대상으로 추출된 그룹의 개수와 각 객체의 명칭을 원래의 모델과 비교하여 그 적용성을 검토하였다.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.14 no.5
• /
• pp.1129-1137
• /
• 1990

Based on the formulation which incorporates large deformation and anisotropy, an elastic-plastic finite element code is developed with membrane element to include the contact treatment. For the analysis of the general sheet metal forming process with contact condition, the treatment of contact is considered by employing the successive skew coordinate system. Three kinds of sheet metal forming processes with contact conditions are analyzed; stretching of a square diaphragm with a hemispherical punch, deep drawing of a circular cup and deep drawing of a square cup. Then the computational results are compared with the experiment. The computed loads and the distribution of the thickness strain are in good agreement with the experiment for all cases. However, the computational results of the thickness strain show the effect of bending can not be ignored in the deep drawing process whereas the effect of bending is negligible in stretching.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.37 no.9
• /
• pp.837-842
• /
• 2009

The efficient dynamic modeling of a satellite with flexible solar arrays is established by using the component mode synthesis technique. A flexible satellite model can be defined as the assembly of two sub-structures, central body and solar array. The reduced models of each substructure, which are expressed in each local frame, are coupled with respect to the satellite reference frame. The dynamic modeling method is applied to the numerical example of a satellite with a single solar array, and is verified by investigating the transfer function results with considering the solar array rotation.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.6 no.2
• /
• pp.121-131
• /
• 1986

The stiffness matrix of circularly curved frame elements including the warping effects is formulated by the solutions of vlasov's differential equations, and the procedure for the elastic static analysis of curved girder systems by the displacement method is presented. The validity of this method has been demonstrated by comparing the analysis results with other solutions. And if the tangential lines of the two frame element axes connected at any nodal point coincide, the transformation to the global coordinate system can be omitted when we analyze the structures consisting of circularly curved elements. The theory introduced in this thesis can be applied with sufficient accuracy to the structures built up with horizontally circular curved frame elements which have closed or open cross sections and are symmetric to the axis perpendicular to the plane of the curvature, such as prestressed concrete box girder bridges.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.13 no.6
• /
• pp.1092-1103
• /
• 1989

본 논문에서는 기존의 금속성형의 유한요소해석에서 사용한 바 있는 기하적경 계조건을 직접 유한요소방정식에 대입하는 방법들을 비교검토하고 3차원박판성형에 적용하기 위하여 개선된 방법을 개발하였다.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.23 no.2
• /
• pp.198-209
• /
• 1999

This study reports the selection of dependent variables for momentum equations in general curvilinear coordinates. Catesian, covariant and contravariant velocity components were examined for the dependent variable. The focus of present study is confined to staggered grid system Each dependent variable selected for momentum equations are tested for several flow fields. Results show that the selection of Cartesian and covariant velocity components intrinsically can not satisfy mass conservation of control volume unless additional converting processes ore used. Also, Cartesian component can only be used for the flow field in which main-flow direction does not change significantly. Convergence rate for the selection of covariant velocity component decreases quickly as with the increase of non-orthogonality of grid system. But the selection of contravariant velocity component reduces the total mass residual of discretized equations rapidly to the limit of machine accuracy and the solutions are insensitive to the main-flow direction.