• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2003년도 춘계학술발표대회 개요집
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• pp.210-212
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• 2003

Finite element analysis of welding processes, which entail phase evolution, heat transfer and deformation, is considered in this paper. Attention focuses on numerical implementation of the thermo-elastic-plastic constitutive equation proposed by Leblond et al in consideration of the transformation plasticity. Based upon the multiplicative decomposition of deformation gradient, hyperelastic formulation is employed for efficient numerical integration, and the algorithmic consistent moduli for elastic-plastic deformations including transformation plasticity are obtained in the closed form. The convergence behavior of the present implementation is demonstrated via a couple of numerical example.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1993년도 봄 학술발표회논문집
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• pp.207-212
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• 1993

In the construction of underground structures, it is critical to accurately predict the ground deformations during excavation. In this paper, a finite element procedure for the computation of solid displacement and fluid pore pressure during incremental excavation is presented based on Biot's theory. The numerical formulation is done using the virtual work principle. The proposed procedure is applied to some example problems with different excavation rates and permeabilities.

• 대한기계학회논문집
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• 제13권4호
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• pp.572-582
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• 1989

본 논문에서는 윗면에 균일한 압력을 받는 외팔보의 굽힘 변형과 고정 자유 지지된 무한길이 스트립의 폭 방향 굽힘변형을 위에 언급된 이론을 적용하여 살펴보고자 한다. 먼저 기본 지배방정식들을 요약하여 변형률의 1차항까지 나타내며 각 경우에 대해 변형을 중심선에 상대적인 단면의 변위와 단면의 회전 그리고 병진을 나타내며 각 경우에 대해 변형을 중심선에 상대적인 단면의 변위와 단면의 회전 그리고 병진을 나타내는 도심의 변위로 분해하고 도심에 상대적인 변위는 Michell에 의한 평판의 해와 St. Venant에 의한 봉의 해를 이용한다. 가정된 변위장으로부터 응력을 구한 다음 적절한 조건 하에서 국부평형방정식을 구하여 전체평형방정식을 유도한다. 또한 이로부터 각 단면의 회전과 중심선의 변위가 구해질 수 있음을 보인다.

• Journal of applied mathematics & informatics
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• 제5권3호
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• pp.811-818
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• 1998

A cylindrical elastic layer in finite deformation s con-sidered. The characteristics of the linear longitudinal wave and the nonlinear shear wave are investigated; the dependence of the later on the parameter of large deformation is given.

• Structural Engineering and Mechanics
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• 제66권5호
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• pp.665-676
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• 2018

In this study, a four-node quadrilateral partial mixed plate element with low degrees of freedom (dofs) is developed for static and free vibration analysis of functionally graded material (FGM) plates rested on Winkler-Pasternak elastic foundations. The formulation of the presented finite element model is based on a parametrized mixed variational principle which is developed recently by the first author. The presented finite element model considers the effects of shear deformations and normal flexibility of the FGM plates without using any shear correction factor. It also fulfills the boundary conditions of the transverse shear and normal stresses on the top and bottom surfaces of the plate. Beside these capabilities, the number of unknown field variables of the plate is only six. The presented partial mixed finite element model has been validated through comparison with the results of the three-dimensional (3D) theory of elasticity and the results obtained from the classical and high-order plate theories available in the open literature.

• 한국해양공학회지
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• 제11권4호
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• pp.7-22
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• 1997

A finite element analysis is performed for lateral buckling problems on the basis of a geometrically nonlinear formulation for a beam with small elastic strain but with possibly large rotations. The total Lagrangian formulation for a general large deformation, which involves finite rotations, is chosen and the exponential map is used to treat finite rotations from the Eulerian point of view. For lateral buckling, the point of vanishing determinant of the resulting unsymmetric tangent stiffness is traced to examine its relationship to bifurcation points. It is found that the points of vanishing determinant is not corresponding to bifurcation points for large deformations in general, which suggests that the present unsymmetric tangent stiffness is not an exact first derivative of internal forces with respect to displacement. This is illustrated through several numerical examples and followed by appropriate discussion.

• Structural Engineering and Mechanics
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• 제49권2호
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• pp.273-283
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• 2014

According to deformation features of pre-twisted bar, its elastic bending and torsion buckling equation is developed in the paper. The equation indicates that the bending buckling deformations in two main bending directions are coupled with each other, bending and twist buckling deformations are coupled with each other as well. However, for pre-twisted bar with dual-axis symmetry cross-section, bending buckling deformations are independent to the twist buckling deformation. The research indicates that the elastic torsion buckling load is not related to the pre-twisted angle, and equals to the torsion buckling load of the straight bar. Finite element analysis to pre-twisted bar with different pre-twisted angle is performed, the prediction shows that the assumption of a plane elastic bending buckling deformation curve proposed in previous literature (Shadnam and Abbasnia 2002) may not be accurate, and the curve deviates more from a plane with increasing of the pre-twisting angle. Finally, the parameters analysis is carried out to obtain the relationships between elastic bending buckling critical capacity, the effect of different pre-twisted angles and bending rigidity ratios are studied. The numerical results show that the existence of the pre-twisted angle leads to "resistance" effect of the stronger axis on buckling deformation, and enhances the elastic bending buckling critical capacity. It is noted that the "resistance" is getting stronger and the elastic buckling capacity is higher as the cross section bending rigidity ratio increases.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계학술대회논문집
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• pp.788-791
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• 2005

Nodal displacements are referred to the Initial configuration in the total Lagrangian formulation and to the last converged configuration in the updated Lagrangian formulation. This research proposes a relative nodal displacement method to represent the position and orientation for a node in truss structures. Since the proposed method measures the relative nodal displacements relative to its adjacent nodal reference frame, they are still small for a truss structure undergoing large deformations for the small size elements. As a consequence, element formulations developed under the small deformation assumption are still valid fer structures undergoing large deformations, which significantly simplifies the equations of equilibrium. A structural system is represented by a graph to systematically develop the governing equations of equilibrium for general systems. A node and an element are represented by a node and an edge in graph representation, respectively. Closed loops are opened to form a spanning tree by cutting edges. Two computational sequences are defined in the graph representation. One is the forward path sequence that is used to recover the Cartesian nodal displacements from relative nodal displacements and traverses a graph from the base node towards the terminal nodes. The other is the backward path sequence that is used to recover the nodal forces in the relative coordinate system from the known nodal forces in the absolute coordinate system and traverses from the terminal nodes towards the base node. One closed loop structure undergoing large deformations is analyzed to demonstrate the efficiency and validity of the proposed method.

• Structural Engineering and Mechanics
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• 제50권1호
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• pp.105-119
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• 2014

This study presents a steel container crane movement analysis and assessment based on structural health monitoring (SHM). The accelerometers are used to monitor the dynamic crane behavior and a 3-D finite element model (FEM) was designed to express the static displacement of the crane under the different load cases. The multi-input single-output nonlinear autoregressive neural network with external input (NNARX) model is used to identify the crane dynamic displacements. The FEM analysis and the identification model are used to investigate the safety and the vibration state of the crane in both time and frequency domains. Moreover, the SHM system is used based on the FEM analysis to assess the crane behavior. The analysis results indicate that: (1) the mean relative dynamic displacement can reveal the relative static movement of structures under environmental load; (2) the environmental load conditions clearly affect the crane deformations in different load cases; (3) the crane deformations are shown within the safe limits under different loads.

• 대한조선학회논문집
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• 제36권4호
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• pp.37-47
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• 1999

본 논문에서는 접수(water entry) 및 이수(water exit) 문제를 유동장의 지배방정식인 2차원 비압축성 Navier-Stokes방정식을 일반좌표계(generalized coordinate system)에서 유한체적법(Finite Volume Method)으로 이산화 하여 해석하였다. 강체의 접수 또는 이수 상황에서 발생하는 자유수면 변형에 대한 처리는 Level-Set[11]기법을 사용하였다. 수치계산결과에서 접수에 대한 유체충격력에 대한 계산결과는 쐐기(wedge)형과 flared-ship 단면의 실험결과[5]와 비교하였으며, 원형실린더의 이수문제에서는 시간에 따른 자유수면의 변형 및 유동장의 특징을 살펴보았다.