• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.8
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• pp.1889-1900
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• 1995

In this study, a large deflection analysis of a plane frame composed of a thin-walled tube in investigated. When bent, a thin-walled tube is usually controlled by local buckling and subsequent bending collapse of the section. So load resistance reaches the yield level in a thin-walled rectangular tube. This relationship can be divided into three regimes : elastic, post-buckling and crippling. In this paper, this relationship is theoretically presented to be capable of describing nonlinearities and a stiffness matrix is derived by introducing a compound beam-spring element. A numerical analysis uses a constant incremental energy method and the solution is obtained by modifying stiffness matrix at elastic/inelastic stage. This analytical results, load-deflection paths show a good agreement with the test results.

• Journal of the Society of Naval Architects of Korea
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• v.45 no.2
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• pp.186-191
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• 2008

A lot of equipments installed in ships must be isolated for relaxing the shock, vibration and noise using the elastic mounts. Most of the elastic mounts are made of the rubber, however it is not easy to design the effective rubber mount. Because, in general, the rubber has a non-linear constitutive characteristics especially for a large deformation. So, there are many difficulties to estimate the accurate structural response of rubber which is the basis of the shape design of the mounts. In this study, the detailed non-linear viscoelastic large deformation finite element analysis method was dealt with. And to verify validity of the present analysis scheme, the results were compared with experiments.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.5
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• pp.1129-1137
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• 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 KSME
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• v.26 no.2
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• pp.96-101
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• 1986

유한요소해석과 관련하여 그 분야와 과정을 소개하고 각각에 대하여 현재 연구의 중점방향과 예상되는 장래 집중연구 과제등을 기술하였다. 특히 공통적 기하학적 자료베이스에서부터 해 법자체와 나아가서 이들 결과의 설계응용의 자동화 또는 전문가 시스템화의 종합적인 방향이 장래 전문적인 제품설계의 방향으로 될 것을 주장하였다. 구분적인 연구는 사용자 편의의전. 후처리 프로그램, 대변형 비선형문제, 비선형 재료문제, 비선형 동적문제, 유한요소 모델링 기법, 설계와의 연계등에서 큰 진전이 있을 것으로 보고 이를 중심으로 기술하였다.

• Journal of the Korea Institute of Military Science and Technology
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• v.2 no.2
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• pp.148-156
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• 1999

The thermal postbuckling and vibration characteristics of cylindrical composite panel subject to thermal loads are analyzed using finite elements. The von-Karman nonlinear displacement-strain relation based on the layerwise theory is applied to consider large deflections due to thermal loads. Cylindrical arc-length method is used to take into account the snapping phenomena. Thermal snapping and vibration characteristics are investigated for various structural parameters such as thickness ratio, shallowness angle and boundary conditions. The present results show that thermal snapping changes the mode shapes as well as static deformations.

• Journal of Korean Association for Spatial Structures
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• v.10 no.2
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• pp.61-68
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• 2010

The collapsing accidents of pipe greenhouses in the farmhouse have been increased duo to heavy snow load. However, the study on exact structure analysis to prevent the collapse of pipe greenhouses is rare and the damage of the farmhouse is annually repeated. The method of existing structure analysis is basically made of linear elastic analysis based on the micro displacement. But the actual stiffness of the pipe greenhouse is significantly weaker than the stiffness of buildings and the load acting on the greenhouses gets to become relatively bigger. It means that the geometry shape of greenhouses changes so that the relation of strain-displacement gets to indicate a nonlinear behavior. Therefore, this study is performed to evaluate the structural safety so as to prevent the collapse of pipe greenhouses, which are the single-span greenhouse(farmhouse guidance shape, G) and multi-span greenhouse(farmhouse supply shape, 1-2W), by performing the large-displacement analysis considering nonlinear effects.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.22 no.6
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• pp.527-532
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• 2009

In this paper simulations for the impact into ceramics and/or metal materials have been discussed. To model discrete nature for fracture and damage of brittle materials, we implemented cohesive-law fracture model with a node separation algorithm for the tensile failure and Mohr-Coulomb model for the compressive loading. The drawback of this scheme is that it requires a heavy computational time. This is because new nodes are generated continuously whenever a new crack surface is created. In order to reduce the amount of calculation, parallelization with MPI library has been implemented. For the high-speed impact problems, the mesh configuration and contact calculation changes continuously as time step advances and it causes unbalance of computational load of each processor. Dynamic load balancing technique which re-allocates the loading dynamically is used to achieve good parallel performance. Some impact problems have been simulated and the parallel performance and accuracy of the solutions are discussed.

• Computational Structural Engineering
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• v.11 no.4
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• pp.321-330
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• 1998

막구조의 초기형상을 결정하기 위하여 막요소의 기하학적 비선형을 고려한 평형방정식을 유도하고, 등장력곡면(equally stressed surface)을 결정하기 위한 알고리즘을 정식화한다. 막구조는 대변형에 의한 기하학적 비선형성을 포함하고, 막구조의 특성상 초기장력에 의한 초기변형을 고려해야 하므로, 본 논문에서는 막구조와 같은 인장구조물의 비선형 수치해석을 수행하기 위한 해석기법으로써, 동적이완법(Dynamic Relaxation Method)에 대한 해석알고리즘을 적용하고, 이 방법에 의해 수행한 해석결과를 검토함으로써 막구조 해석에 적용 가능한 수치해석기법을 제시하고, 수치해석에 대한 예를 통해 본 해석법의 타당성을 검증한다.

• Journal of Korean Society of Steel Construction
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• v.13 no.6
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• pp.661-672
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• 2001

The present study is concerned with the arc-length method in the investigation of the large deflection behavior of spatial structures with composite materials. This study should be able to trace the main equilibrium path by automatically varying the arc-length size of individual solution steps with the variation of the curvature of the nonlinear equilibrium path. A quasi-elastic method is used for the solution for viscoelastic analysis of the reticulated spatial structures. Elastic modulus of composite materials is defined by micro mechanical materials modeling method and nonlinear equilibrium path is traced with various load types. To demonstrate the effectiveness of the present strategies, numerical examples of reticulated spatial truss is given and compared with solutions using other methods.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.6
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• pp.503-508
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• 2007

In this study, the aeroelastic response and stability of bearingless rotors are investigated using a large deflection beam theory. The outboard main blade, flexbeam, and torque tube are all assumed to be an elastic beam undergoing arbitrary large displacements and rotations. The finite element equations of motion obtained from Hamilton's principle. Two-dimensional quasi-steady strip theory is used to evaluate aerodynamic forces. In hover, the modal approach method based on coupled rotating natural modes is used for the stability analysis. In forward flight, the nonlinear periodic blade steady response is obtained by integrating the full finite element equation in time through a coupled trim procedure with a vehicle trim. The results of the full finite element analysis using the large deflection beam theory are compared with those of a previously published modal analysis using the moderate deflection-type beam theory.