• Steel and Composite Structures
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• 제30권4호
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• pp.305-313
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• 2019

Creating different cutout shapes in order to make doors and windows, reduce the structural weight or implement various mechanisms increases the likelihood of buckling in thin-walled structures. In this study, the effect of cutout shape and geometric imperfection (GI) is simultaneously investigated on the critical buckling load and knock-down factor (KDF) of composite cylindrical shells. The GI is modeled using single perturbation load approach (SPLA). First, in order to assess the finite element model, the critical buckling load of a composite shell without cutout obtained by SPLA is compared with the experimental results available in the literature. Then, the effect of different shapes of cutout such as circular, elliptic and square, and perturbation load imperfection (PLI) is investigated on the buckling behavior of cylindrical shells. Results show that the critical buckling load of a shell without cutout decreases by increasing the PLI, whereas increasing the PLI does not have a great impact on the critical buckling load in the presence of cutout imperfection. Increasing the cutout area reduces the effect of the PLI, which results in an increase in the KDF.

• Journal of Mechanical Science and Technology
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• 제18권5호
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• pp.808-813
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• 2004

The stress analysis on orthotropic composite cylindrical shells with one circular or one elliptical cutout subjected to an axial force is carried out by using an analytical and experimental method. The composite cylindrical shell governing equation of the Donnell's type is applied to this study and all results are presented by the stress concentration factor. The stress concentration factor is defined as the ratio of the stress on the region around a cutout to the nominal stress of the shell. The stress concentration factor is classified into the circumferential stress concentration factors and the radial stress concentration factors due to the cylindrical coordinate of which the origin is the center of a cutout. The considered loading condition is only axial tension loading condition. In this study, thus, the maximum stress is induced on perpendicular region against axial direction, on the coordinate. Various cutout sizes are expressed using the radius ratio, (equation omitted), which is the radius of a cutout over one of the cylindrical shell. Experimental results are obtained using strain gages, which are attached around a cutout of the cylindrical shell. As the result from this study, the stress concentration around a cutout can be predicted by using the analytical method for an orthotropic composite cylindrical shell having a circular or an elliptical cutout.

• Steel and Composite Structures
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• 제28권3호
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• pp.319-329
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• 2018

The field around additional cutout of the floor beam web in orthotropic bridge deck was subjected to high stress concentration, especially the weld toe between floor beam and U shaped rib and the free edge of the additional cutout. Based on different considerations, different geometrical parameters of additional cutout were proposed in European, American and Japanese specifications, and there remained remarkable differences among them. In this study, considering influence of out-of-plane deformation of floor beam web and U shaped rib, parameter analysis for additional cutout under typical load cases was performed by fine finite element method. The influence of additional cutout shape and height to the stress distribution around the additional cutout were investigated and analyzed. Meanwhile, the static and fatigue test on this structure details was carried out. The stress distribution was consistent with the finite element analysis results. The fatigue property for additional cutout height of 95mm was slightly better than that of 61.5 mm.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.1177-1182
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• 2006

This paper is concerned with the vibration analysis of a simply-supported rectangular plate with a circular cutout. Even though there have be en many methods developed for the free vibration of the rectangular plate with a rectangular cutout., very few research has been carried out for the rectangular plate with a circular cutout. In this paper, a new methodology called independent coordinate coupling method, which was developed to save the computational effort for the free vibration analysis of rectangular plate with a rectangular cutout, is applied to the case of circular cutout. The independent coordinate coupling method employs the global coordinate system for the plate and the local coordinate system for the cutout. In the case of the rectangular plate with a circular cutout, the global coordinate system is the Cartesian co ordinate system and the local coordinate system is the polar coordinate system. By imposing the compatibility condition, the relationship between the global coordinates and the local coordinates is derived. This equation is then used for the calculation of the mass and stiffness matrices resulting in eigenvalue problem. The numerical results show the efficacy of the proposed method.

• 한국소음진동공학회논문집
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• 제16권6호
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• pp.643-650
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• 2006

This paper is concerned with the vibration analysis of a simply-supported rectangular plate with a circular cutout. Even though there have been many methods developed for the free vibration of the rectangular plate with a rectangular cutout, very few research has been carried out for the rectangular plate with a circular cutout. In this paper, a new methodology called independent coordinate coupling method, which was developed to save the computational effort for the free vibration analysis of rectangular plate with a rectangular cutout, is applied to the case of circular cutout. The independent coordinate coupling method employs the global coordinate system for the plate and the local coordinate system for the cutout. In the case of the rectangular plate with a circular cutout, the global coordinate system is the Cartesian coordinate system and the local coordinate system is the polar coordinate system. By imposing the compatibility condition, the relationship between the global coordinates and the local coordinates is derived. This equation is then used for the calculation of the mass and stiffness matrices resulting in eigenvalue problem. The numerical results show the efficacy of the proposed method.

• Structural Engineering and Mechanics
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• 제77권2호
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• pp.245-259
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• 2021

In this research, the influence of the laminate stacking sequence on thermal stress distribution in symmetric composite plates with a quasi-square cutout subjected to uniform heat flux is examined analytically using the complex variable technique. The analytical solution is obtained based on the thermo-elastic theory and the Lekhnitskii's method. Furthermore, by employing a suitable mapping function, the solution of symmetric laminates containing a circular cutout is extended to the quasi-square cutout. The effect of important parameters including the stacking sequence of laminates, the angular position, the bluntness, the aspect ratio of cutout, the flux angle and the composite material are examined on the thermal stress distribution. It is found out that the circular shape for cutout may not necessarily be the optimum geometry for all stacking sequences. The finite element analysis results are used to validate the analytical solution.

• 한국소음진동공학회논문집
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• 제21권6호
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• pp.506-513
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• 2011

This paper is concerned with a study on the control effect of the MR damper using the cutout piston. The MR damper has passive damping force by the oil pressure and controllable damping force by the magnetic effect. As the velocity of the MR damper's piston increases the passive damping force increases and the ratio of the controllable damping force to the total damping force is decreased. Consequently, the control performance of the MR damper is reduced according to the increase of the velocity. In this paper, the cutout piston concept is applied to the MR damper to improve MR damper's control performance by reducing the passive damping effect. The MR damper with the cutout piston has been designed and manufactured and its hydraulic and electromagnetic analysis has been performed to predict its performance. The control performances of the MR damper with the cutout piston are verified through the comparison of experiment results and simulation results.

• Steel and Composite Structures
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• 제29권1호
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• pp.39-51
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• 2018

Position of a circular or elliptical cutout within an orthotropic plate has great influence on its buckling behavior. This paper aims at finding the optimal position (both location and orientation) of a single circular/elliptical cutout, within an orthotropic rectangular plate, that maximizes the critical buckling load. We consider linear buckling of simply supported orthotropic plates under uniaxial edge loads. To obtain the optimal positions of the cutouts, we have employed a MATLAB optimization routine coupled with buckling computation in ANSYS. Our results show that the position of the cutout that maximizes the buckling load has great dependence on the material properties, laminate configurations, and the geometrical parameters of the plate. These optimal results, for a number of plate geometries and cutout sizes, are reported in this paper. These results will be useful in the design of perforated orthotropic plates against buckling failure.

• International Journal of Ocean System Engineering
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• 제1권2호
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• pp.95-101
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• 2011

Perforated plates with cutouts (or holes) are widely used in structural members. These cutouts provide stress concentration in plates. Extensive studies have been carried out on stress concentration in perforated plates, which consider cutout shapes, boundary conditions, bluntness of cutouts, and more. This study presents stress concentration analyses of perforated plates with not only various cutouts and bluntness but also different cutout orientations. Especially, the effect of cutout orientation on stress concentration is emphasized since structural members have become more complicated recently. To obtain stress concentration patterns, a finite element program, ANSYS, is used. For the designated goal, three parameters are considered as follows: the shapes of polygonal cutouts (circle, triangle, and square), bluntness (a counter measure of radius ratio, r/R), and rotation of cutouts (${\theta}$). From the analyses, it is shown that, in general, as bluntness increases, the stress concentration increases, regardless of the shape and rotation. A more important finding is that the stress concentration increases as the cutouts become more oriented from the baseline, which is the positive horizontal axis (+x). This fact demonstrates that the orientation is also a relatively significant design factor to reduce stress concentration. In detail, in the case of the triangle cutout, orienting one side of the triangle cutout to be perpendicular to the applied tensile forces is preferable. Similarly, in the case of the square cutout, it is more advantageous to orient two sides of square cutout to be perpendicular to the applied tensile force. Therefore, at the design stage, determining the direction of a major tensile force is required. Then, by aligning those polygon cutouts properly, we can reduce stress concentration.

• 한국콘텐츠학회논문지
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• 제11권6호
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• pp.67-75
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• 2011

본 논문에서는 비디오 입력으로부터 UCC 제작에 적합한 컷아웃 애니메이션을 생성하기 위한 방법을 제안한다. 본 논문의 시스템은 관절 구조 캐릭터를 기반으로 하여 사용자가 쉽게 관절 캐릭터를 생성할 수 있는 인터페이스를 제공하며 비디오 입력으로부터 생성된 관절 캐릭터의 동작 정보를 추출한다. 실제 컷아웃 애니메이션과 같이 보이도록 종이 효과 렌더링, 그림자 렌더링을 적용하여 관절 캐릭터의 애니메이션을 생성하였다. 본 논문의 시스템을 이용하여 사용자는 여러 가지 비디오 입력으로부터 다양한 캐릭터 동작을 가진 컷아웃 애니메이션을 생성할 수 있었다.