• Journal of the KSME
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• v.34 no.7
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• pp.502-509
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• 1994

유한요소법은 1960년 Clough에 의하여 명명된 이래 구조역학적인 문제에 이용되어 오다가 오 늘날에는 공학적 문제를 해결하기 위한 가장 보편적인 도구가 되었다. 유한요소법의 사용이 이와 같이 보편화될 수 있었던 주요인은 컴퓨터의 발달과 무관하지 않겠지만 해석프로그램을 한 번 개발하면 동일한 특성의 다양한 구조물을 누구나 숩게 해석할 수 있는 범용성 때문으로 생각 된다. 그러나 유한요소법도 일종의 수치해법이기 때문에 수식화 방법과 해석하는 사람에 따라서 그 결과에 다소 차이가 생기는 것도 틀림없는 사실이다. 따라서 1980년대 초부터 학자들은 유 한요소법의 정확도 문제에 관심을 갖게 되었고 최근에는 누가 해석하든지 신뢰성 있는 동일한 결과를 얻을 수 있는 방법과 미리 해석결과의 정확도를 지정하여 입력시킬 때 이에 따른 결과를 얻기 위한 방법에 많은 연구를 하고 있다.

• Structural Engineering and Mechanics
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• v.57 no.6
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• pp.1143-1156
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• 2016

This paper presents a comparative study of finite element method (FEM) and analytical method for the plane problem of a layered composite containing an internal perpendicular crack in literature. The layered composite consists of two elastic layers having different elastic constants and heights. External load is applied to the upper elastic layer by means o a rigid punch and the lower elastic layer rests on two simple supports. Numerical simulations are realized by the world wide code ANYS software. Two dimensional analysis of the problem is carried out and the results are verified by comparison with solutions reported in literature. Main goal of the numerical simulation is to investigate the normal stress ${\sigma}_x$(0, y), stress intensity factors at the crack factor and the crack opening displacements.

• Smart Structures and Systems
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• v.4 no.4
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• pp.407-428
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• 2008

The nonlinear mechanics of cable vibration is caught either by analytical or numerical models. Nevertheless, the choice of the most appropriate method, in consideration of the problem under study, is not straightforward. A feedback control policy might even enhance the complexity of the system. Thus, in order to design a suitable controller, different approaches are here adopted. Devices mounted transversely to the cable in the two directions, close to one of its ends, supply the feedback control action based on the observation of the response in a few points. The low order terms of the control law are, at first, analyzed in the framework of linear models. Explicit analytic solutions are derived for this purpose. The effectiveness of high order terms in the control law is then explored by means of a finite element model(FEM), which accounts for high order harmonics. A suitably dimensional analytical Galerkin model is finally derived, to investigate the effectiveness of the proposed control strategy, when applied to a physical model.

• Advances in concrete construction
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• v.4 no.3
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• pp.173-194
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• 2016

This paper consists in a study of a new contructive sequence of road viaducts with Movable Scaffolding System (MSS) using numerical tools based on finite element method (FEM). Traditional and new sequences are being used in Spain to build viaducts with MSS. The new sequence permits an easier construction of one span per week but implies some other issues related to the need of two prestressing stages per span. In order to improve the efficiency of the new sequence by reducing the number of prestressing stages per span, two solutions are suggested in this study. Results show that the best solution is to introduce the 100% of the prestressing force at the self-supporting core in order to improve the road viaduct construction with movable scaffolding system by reducing execution time without increasing economic costs.

• Structural Engineering and Mechanics
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• v.61 no.3
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• pp.335-345
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• 2017

Free vibration analysis for continuous bridge under any number of vehicles is conducted in this paper. Calculation strategy for natural frequency and mode shape is proposed based on Euler-Bernoulli beam theory and numerical assembly method. Firstly, a half-car planar model is adopted; equations of motion and displacement functions for bridge and vehicle are established, respectively. Secondly, the undermined coefficient matrices for wheels, vehicles, intermediate support, left-end support and right-end support are derived. Then, the numerical assembly technique for conventional finite element method is adopted to construct the overall matrix of coefficients for whole system. Finally, natural frequencies and corresponding mode shapes are determined based on iterative method and overall matrix solution. Numerical simulation is presented to verify the effectiveness of the proposed method. The results reveal that the solutions of present method are exact ones. Natural frequencies and associate modal shapes of continuous bridge under different conditions of vehicles are investigated. The influences of vehicle parameters on natural frequencies are also demonstrated.

• Laser Solutions
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• v.11 no.3
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• pp.10-15
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• 2008

This study is aimed to analyse the laser glass bonding process numerically. Due to the viscoelastic behaviour of glass, the extremely large deformation of the frit seal is resulted continuously over the transition temperature, so that the thermal boundary condition be changed in the entire calculation process. The commercial FEM algorithm is restrictively able to remesh the large geometrical boundary shape and to adapt the boundary conditions simultaneously. According to our manual adaptation of increasing the laser line intensity to 700 mW/mm, it is possible to estimate the thermal glass bonding process under the fracture stress in principle. But it should be studied further in the case of high laser line intensity.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.4 s.97
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• pp.474-482
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• 2005

A theoretical method is presented to investigate the thermoelastic and dynamic response of functionally graded material (FGM) rectangular plates made up of metal and ceramic. The temperature is assumed to be constant in the plane of the plate and to vary in the thickness direction only. Material properties are assumed to be temperature-dependant, and vary continuously through the thickness according to a power law distribution in terms of the volume fraction of the constituents. The third order shear deformation theory (TSDT) to account for rotary inertia and transverse shear strains is adopted to formulate the theoretical model. The modal analysis technique is used to develop the analytic solutions of the dynamic problem. The effect of material compositions and temperature fields is examined. The present theoretical results are verified by comparing with those from finite element analysis by ANSYS.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.6
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• pp.580-586
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• 2011

This paper addresses the effect of transverse shear deformation and rotary inertia on the natural frequency of beams under axial loads. It has been reported in the author's paper using a finite element analysis that the Timoshenko effect in a rotating disk deceases and then increases again with increasing rotation speed. To validate the phenomenon, the simply-supported beams under uniform tension are selected in this study since they have exact solutions in vibration problem. The results show that the axial tension in beams would not make the Timoshenko effect decrease monotonically but could make the effect increase again unlike the results reported in the other studies for beams.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.11 s.176
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• pp.125-134
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• 2005

Recently, there have been reported on the results that the material life is reduced by fretting conditions and the initial crack made by low stress under fretting. The purpose of this paper is to show that the results of finite element analysis for the fretting contact problems of a flat rounded punch are nearly consistent with the theoretical solutions and to research that the results about effects of the contact zone according to geometries and mechanical properties of pad.

• International Journal of Precision Engineering and Manufacturing
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• v.3 no.1
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• pp.43-48
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• 2002

This paper describes an automated computer-aided engineering (CAE) system for three-dimensional structures. An automatic finite element mesh-generation technique, which is based on fuzzy knowledge processing and computational geometry techniques, is incorporated into the system, together with a commercial FE analysis code, and a commercial solid modeler. The system allows a geometry model of interest to be automatically converted to different FE models, depending on the physical phenomena of the structures to be analyzed, i.e., electrostatic analysis, stress analysis, modal analysis, and so on. Also, with the aid of multilayer neural networks, the present system allows us to obtain automatically a design window in which a number of satisfactory design solutions exist in a multi-dimensional design parameter space. The developed CAE system is successfully applied to evaluate an electrostatic micromachines.