• 대한기계학회논문집
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• 제16권5호
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• pp.829-837
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• 1992

본 연구에서는 열간박판압연공정에서의 소성유동, 롤압력, 온도분포를 예측하 기 위한 새로운 방법을 제안하고 있다. 제안된 방법은 유한요소 수식화에 바탕을 두 고 있으며 박판의 소성유동과 온도판의 소성유동과 롤-박판 접촉면에서의 롤압력을 예 측하기 위하여 Hwang등이 제안한 벌칙 강소성 유한요소 수식화기법을 제시하였으며 제 안된 방법에 대한 해의 정확도는 문헌에서의 이론해와 시뮬레이션 결과를 비교하여 확 인하였다. 또한 박판에서의 온도장, 속도장과 롤에서의 온도장의 연계해석을 위한 반복계산방법이 제안되었다. 제안된 방법들을 이용하여 다양한 공정에 대한 시뮬레 이션을 수생하였으며 다양한 공정조건에 대한 롤-박판 시스템의 열적특성과 롤간극에 서 박판의 유동특성을 조사하였다.

• Coupled systems mechanics
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• 제4권4호
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• pp.365-383
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• 2015

Strip footing is an important type of shallow foundations and is commonly used beneath the walls. Analysis of shallow foundation involves the determination of stresses and deformations. Element free Galerkin method, one of the important mesh free methods, is used for the determination of stresses and deformations. Element free Galerkin method is an efficient and accurate method as compared to finite element method. The Element Free Galerkin method uses only a set of nodes and a description of model boundary is required to generate the discrete equation. Strip footing of width 2 m subjected to a loading intensity of 200 kPa is studied. The results obtained are agreeing with the values obtained using analytical solutions available in the literature. Parametric study is done and the effect of modulus of deformation, Poisson's ratio and scaling parameter on deformation and stresses are determined.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2000년도 추계학술대회 논문집
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• pp.42-48
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• 2000

This paper is concerned with a simulation-based process design for the tension levelling of metallic strips based on the elasto-plastic finite element analysis with reduced integration and hourglass control. The tension levelling process is performed to elongate the strip plastically in combination of tensile and bending strain by a controlled manner so that all longitudinal fibers in the strip have an approximately equal amount of length and undesirable strip shapes are corrected to the flat shape. The analysis deals with a method for calculating the quantitative level of the curl to investigate the roll arrangements and intermesh suitable to elimination of the curl. The analysis provides the information about the intermesh effect on the amount, the tension effect and distribution of the strain as well as the stress in order to determine the amount of elongation for correction of the irregular shape. The desired elongation is referred to determine the number of work rolls and the value of tension. Especially, the analysis investigates tile effect of the mesh size in the non-steady state finite element analysis on the amount and distribution of the strain.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2002년도 금형가공 심포지엄
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• pp.266-273
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• 2002

Milli-structure components are classified as a component group whose size is between macro and micro scales, that is, about less than 20mm and larger than 1mm. The bending of these components of thin sheets has a typical phenomenon of bulk deformation because of the forming size. The recent trend towards miniaturization causes an increased demand for parts with very small dimensions. The conceptual miniature bending process enables the production of such parts with high productivity and accuracy. The stress values of the flow curve decrease with miniaturization, which means that coarse grained materials show a higher resistance against deformation, when the grain size is in the range of the sheet thickness. In this paper, a new numerical approach is proposed to simulate intergranular milli-structure in forming by the finite element method. The grain element and grain boundary element are introduced to simulate the milli-structure of strip in the bending. The grain element is used to analyze the deformation of individual grain while the grain boundary element is for the investigation on the movement of the grain boundary. Also, the result of the finite element analysis is confirmed by a series of milli-sized forming experiments.

• 한국재난정보학회 논문집
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• 제11권4호
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• pp.534-541
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• 2015

본 연구는 양단이 단순지지된 조건을 갖는 다층 원통쉘을 해석하는 방법을 제시하였고, 3차원 응력 특성을 규명한 것이다. 지배방정식은 편미분방정식을 상미분방정식으로 변환을 가정한 유한요소 개념을 이용하여 유한대판법 해석법을 이용하여 수치해서하였다. 특히 단순지지 조건을 갖는 3차원 다층원통쉘에 대해서는 시행함수로서 삼각함수로 구성되는 보의 고유함수로 구성되는 경우에 대해 해석하였다. 층 재료는 강재 또는 콘크리트로하고 층두께, 원통길이 등 파라메터를 다양하게 변화시켜 다층원통쉘에 미치는 영향을 검토한다.

• 대한조선학회지
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• 제16권3호
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• pp.1-8
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• 1979

Various approaches to the analysis of stiffened plating in ship structures have been proposed by a number of researchers. Among them, the finite element method is known to be the most powerful method. However, for many parts of ship's structure having simple geometry and boundary conditions, the F.E.M. is often extravagant and unnecessary. In this paper, the authors have attempted to introduce the finite strip method which was proposed by Y.K. Cheung to avoid the difficulties involved in F.E.M. The results of calculations on the displacements and stresses in various plates with or without stiffeners were satisfactory, which shows the F.S.M. is useful for structural analysis of ship's plating.

• Structural Engineering and Mechanics
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• 제12권3호
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• pp.313-328
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• 2001

A multi-span bridge has the peak value of resultant girder moment or membrane stress at the interior support. In this paper, the spline finite strip method (FSM) is modified to obtain the more appropriate solution at the interior support where the peak values of solution exist. The modification has been achieved by expressing the shape function with non-periodic B-splines which have multiple knots at the boundary. The modified B-splines have the useful feature for interpolating the curve with sudden change in curvature. Moreover, the modified spline FSM is very efficient in analyzing multi-span box girder bridges, since a bridge can be modeled by an assembly of strips extended along the entire bridge length. Numerical examples of the bridge analysis have been performed to verify the efficiency and accuracy of the new spline FSM.

• 소성∙가공
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• 제25권2호
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• pp.130-135
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• 2016

Rolled products often have residual stresses or strip waves that are beyond the customer’s tolerance. To resolve this problem, skin-pass rolling is widely used during post-processing of such products. Because a short contact length compared to the strip width is a characteristic of skin-pass rolling, several numerical analyses have been previously conducted based on a two-dimensional approach. In the current study, a series of simulations was conducted using numerical analysis of three-dimensional elastic-plastic finite element method.

• 소성∙가공
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• 제25권2호
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• pp.136-140
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• 2016

Although the finite element method is a good tool to analyze skin-pass rolling, it is hard to be applied in the field because of its long calculation time. In the current study, simple numerical models were developed for the prediction of roll force and residual stress profiles along the strip width. These models are based on finite element analysis and a coupled solution of Sims’ equation and Hitchcock’s formula. The results indicate that plastic strains can be represented as in simple equations of the deformed roll profile and the initial thickness of the strip.

• Structural Engineering and Mechanics
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• 제8권3호
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• pp.233-242
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• 1999

In the present study, the elasto-plastic analysis of prismatic plate structures subjected to pure bending is carried out using the finite strip method. The end cross-sections of the structure are assumed to remain plane during deformation, and the compatibility along corner lines is ensured by choosing proper displacement functions. The effects of both the initial geometrical imperfections and residual stresses due to fabrication are included in the combined geometrically and materially nonlinear simulation. The von-Mises yield criterion and the Prandtl-Reuss flow theory of plasticity are applied in modelling the elasto-plastic behavior of material. Newton-Raphson iterations are carried out as the rotation of the end cross sections of the structure is increased step by step. The parameter representing the overall axial strain of structure is adjusted constantly during the iteration process in order to eliminate the resulting overall axial force on any cross-section of the structure in correspondence with the assumption of zero axial force in pure bending. Several numerical examples are presented to validate the present method and to investigate the effects of some material and geometrical parameters.