• Title/Summary/Keyword: Curved-DOEs

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Development of Al Bumper Back Beam by Using Curvature Extrusion Process (곡률압출공정을 이용한 알루미늄 Bumper Back Beam 개발)

  • Lee, Sang-Kon;Jo, Young-June;Kim, Byung-Min;Park, Sang-Woo;Oh, Kae-Hee
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.33 no.5
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    • pp.502-507
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    • 2009
  • Curvature extrusion process has several advantages in comparison to the conventional extrusion and bending process. In the curvature extrusion, the extruded part is directly bent during extrusion. Therefore, it does not need additional bending process after extrusion. In the curvature extrusion process, it is possible to produce curved extruded products that have a constant or various curvatures. It is essential that we predict the curvatures of the extruded product to meet the required curvatures. This paper proposed a theoretical model that can predict the curvature of extruded product produced by the curvature extrusion process. Using the proposed model the movement of guide tool that causes the bending of extruded product was controlled to produce the required curved automotive Al bumper back beam. The effectiveness of the proposed prediction model and the movement of guide tool were verified by the FE analysis and curved extrusion experiment.

Bending analysis of doubly curved FGM sandwich rhombic conoids

  • Ansari, Md I.;Kumar, Ajay;Bandyopadhyaya, Ranja
    • Structural Engineering and Mechanics
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    • v.71 no.5
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    • pp.469-483
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    • 2019
  • In this paper, an improved mathematical model is presented for the bending analysis of doubly curved functionally graded material (FGM) sandwich rhombic conoids. The mathematical model includes expansion of Taylor's series up to the third degree in thickness coordinate and normal curvatures in in-plane displacement fields. The condition of zero-transverse shear strain at upper and lower surface of rhombic conoids is implemented in the present model. The newly introduced feature in the present mathematical model is the simultaneous inclusion of normal curvatures in deformation field and twist curvature in strain-displacement equations. This unique introduction permits the new 2D mathematical model to solve problems of moderately thick and deep doubly curved FGM sandwich rhombic conoids. The distinguishing feature of present shell from the other shells is that maximum transverse deflection does not occur at its center. The proposed new mathematical model is implemented in finite element code written in FORTRAN. The obtained numerical results are compared with the results available in the literature. Once validated, the current model was employed to solve numerous bending problems by varying different parameters like volume fraction indices, skew angles, boundary conditions, thickness scheme, and several geometric parameters.

Finite element modeling of rolled steel shapes subjected to weak axis bending

  • Saliba, Najib G.;Tawk, Issam;Gergess, Antoine N.
    • Steel and Composite Structures
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    • v.29 no.2
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    • pp.161-173
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    • 2018
  • Point bending is often used for cambering and curving structural steel girders. An analytical solution, applicable in the elasto-plastic range only, that relates applied loads to the desired curve was recently developed for inducing horizontal curves using four-point bending. This solution does not account for initial residual stresses and geometric imperfections built-in hot-rolled sections. This paper presents results from a full-scale test on a hot-rolled steel section curved using four-point bending. In parallel, a numerical analysis, accounting for both initial geometric imperfections and initial residual stresses, was carried out. The models were validated against the experimental results and a good agreement for lateral offset and for strain in the elasto-plastic and post-plastic ranges was achieved. The results show that the effect of initial residual stresses on deformation and strain is minimal. Finally, residual stresses due to cold bending calculated from the numerical analysis were assessed and a revised stress value for the service load design of the curved girder is proposed.

Distribution of Wheel Loads on Curved Steel Box Girder Bridges (곡선 강상자형교의 윤하중 분배)

  • Kim, Hee-Joong;Lee, Si-Young
    • Journal of the Korean Society of Hazard Mitigation
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    • v.8 no.1
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    • pp.9-14
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    • 2008
  • In the case of horizontally curved bridges, the use of curved composite box girder bridges are increased due to its functionality and for aesthetical reason. As it compared with the open section, the steel box girder bridges have advantages to resistant of distortion and corrosion. In practice the grid analysis is conducted by utilizing only the cross beam. Since the stiffness of the concrete slab is not included in the grid analysis, the cross beam is induced the distribution of the live load. In this study the affects of the radius of curvature, the number of diaphragm and cross beam to the load distribution of the curved steel box girder bridge was investigated by applying the finite element method. The results indicate that the curvature of curved bridge had a large affect of the load distribution and as the curvature was increased the load distribution factor was increased. A single diaphragm at the center of girder is important role for the load distribution effects and structural stability, but additional diaphragm did not affect it as much. The affects of the cross beam to the load distribution were investigated and its influence was minor. It can be safely concluded that the addition of cross beam does not aid the purpose of the live load distribution. And the stiffness of concrete slab for the load distribution effects should be concerned in the design of curved steel box girder bridges.

Development of a pipeline robot like foxtail (강아지풀 형상을 닮은 관내 주행로봇 개발)

  • Choi, Yong-Ho;Yang, Hyun-Suk;Park, No-Chul
    • Proceedings of the KSME Conference
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    • 2007.05a
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    • pp.1167-1172
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    • 2007
  • Generally inpipe robot needs force above standing for contacting robot to pipe. If the environment of the pipe-inside does not change, there is not a problem. But if the pipe radius change, or occur the obstacle which it does not intend, problem gets. So it uses a different system and must know an environment change, and changing the shape or a form of the robot. The research uses the flexible leg and is the robot which is adapted to the environment change of the pipe. The advantage of this robot is possible to move when it does not need to recognize a change of environment of pipe. Leg is bend with one direction. When it moves part that there are legs effect of leg direction the robot is moved with only one direction. If friction between legs and pipe is sufficient, not only verticality pipe moving, but also curved pipe moving. Also the obstacle of the pipe inside occurs and the diameter of the pipe inside changes, this robot can move if it does not use another system or device.

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Spacing of Intermediate Diaphragms Horizontally Curved Steel Box Girder Bridges considering Bending-distortional Warping Normal Stress Ratio (곡선 강박스 거더의 휨-뒤틀림 응력비에 따른 중간 다이아프램 간격)

  • Lee, Jeong-Hwa;Lee, Kee-Sei;Lim, Jeong-Hyun;Choi, Jun-Ho;Kang, Young-Jong
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.16 no.9
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    • pp.6325-6332
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    • 2015
  • Although distortions of horizontally curved box girder are more susceptible than which of the straight girder due to curvature effect, current domestic design standards does not present spacing of intermediate diaphragms for the curved box girder. In this study, parametric studies for straight and curved box girder considering distortional warping normal stresses based on linear finite element analysis were carried out. Single span curved girders were chosen for analysis based on current domestic bridge data with 1-6 of solid intermediate diaphragms, 0-30 degree of subtended angle, 30m and 60m of span length and 2-3m of flange width and web height. The adequate spacing of diaphragms for the box girder were suggested considering subtended angles and bending and distortional warping normal stress ratios with 5%, 10%, 15% and 20%. The analysis results were also compared to a current design standard and suggested spacing of diaphragm were evaluated.

On the Analysis of Vertical-axis Wind Rotor (수직축 풍력발전기의 해석에 관하여)

  • ;;Lee, Chung-Oh
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.3 no.2
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    • pp.60-67
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    • 1979
  • Aerodynamic forces acting on a curved blade are computed theoretically taking into account the variation of wind speed over the blade to investigate the performance of a vertical axis wind rotor. It is shown that the rotor does not self start at the rated wind speed without a supplementary starting device and that most of the power output is contributed by the central portion of the rotor, and the use of spoilers for limiting the maximum rotational speed is needed for safety. It is also shown that provision of skew angle to the blade does not improve the starting characterstics and only reduces the maximum power output. The effects of geometric variables such as skew angle, blade solidity and ratio of the rotor height to diameter are also discussed.

A STUDY OF SUBDIVISION METHOD TO THREE AND FIVE SIDED FACES BASED ON REGULAR POLYGON

  • Muraki, Yuta;Konno, Kouichi;Tokuyama, Yoshimasa
    • Proceedings of the Korean Society of Broadcast Engineers Conference
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    • 2009.01a
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    • pp.551-556
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    • 2009
  • 3-D CAD (Computer Aided Design) system is an indispensable tool for manufacturing. A lot of engineers have studied for the methods to generate a curved surface on an N-sided shape, which is the basic technology of 3-D CAD systems. This surface generation, however, has three problems on the case of long and narrow shapes: the resultant surface is distorted, the surface is not continuous to adjacent surfaces, or additional user inputs are required to generate the surface. Conventional methods have not yet solved these problems at the same time. In this paper, we propose the method to generate internal curves that divide a long and narrow shape into regular N-sided sections so as to divide the shape into an N-sided section and four-sided ones. Our method controls the shape of internal curves by dividing an N-sided long and narrow shape into an N-sided section and four-sided ones, and solves distortion of the generated curved surface. In addition, each of the generated sections is interpolated with G1-continuous surfaces. This process does not require any user's further input. Therefore, the three problems mentioned above will be solved at the same time.

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Forming Analysis of A5083 Thick Plate for Moss Spherical LNG Tank and Prediction of Springback (알루미늄 후판을 이용한 Moss Spherical 타입의 LNG탱크 곡면 성형해석 및 스프링백 예측)

  • Yoon, J.H.;Jeon, H.W.;Lee, J.H.;Kim, B.M.
    • Transactions of Materials Processing
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    • v.21 no.5
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    • pp.305-311
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    • 2012
  • One of the main methods of building LNG tankers uses the Moss spherical tank design since it can be precisely analyzed with respect to reliability and safety of construction by stress analysis. Aluminum alloy 5083 is generally used in the Moss spherical tank design for the wall in constructing the LNG tanker. This aluminum alloy does not have low temperature brittleness, but has good corrosion resistance, good weldability, and excellent material properties for the application. The Moss spherical tank is constructed with several sections of A5083 thick plate with curved surfaces, which are welded together. It is essential to predict the amount of springback for the deformed thick plates in design to insure a reliable construction because the structure needs to be assembled into a perfect sphere. Unless the initial construction meets the design, there are additional processing costs for reworking to meet the specifications as well as a cost penalty paid to a consumer. In this paper, FE analyses were conducted to predict the amount of springback for various forming conditions and forming processes. The various forming processes were evaluated with respect to reducing springback and compared with the conventional forming process used for curved surfaces of thick Al plate.

Effect of Crosswind on Derailment of Railway Vehicles Running on Curved Track at Low Speed

  • Hosoi, Takahiro;Tanifuji, Katsuya
    • International Journal of Railway
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    • v.5 no.2
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    • pp.93-101
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    • 2012
  • Owing to the lightening of railway vehicles and increased operation speeds, the reduction of running safety in the presence of crosswind is becoming an important problem. In particular, the running safety tends to decrease when vehicles run on curved track. When a crosswind acts on a vehicle negotiating a curve from the outer side, flange climbing can occur. In this study, a full-vehicle model was constructed using the multi-body simulation software SIMPACK, and a simulation of a bogie vehicle with two-axle trucks negotiating a curve was carried out to examine the running safety under the condition where a crosswind acts on the vehicle from the outer side of the curve. As a result, it was verified that the derailment coefficient of the first wheelset becomes large in the exit transition curve and the coefficient of the third wheelset does in the entrance transition curve, and this trend becomes pronounced at low operation speeds in the presence of a stronger crosswind. It was also shown that the critical derailment coefficients obtained by modified Nadal's formula considering the effect of attack angle become close to the actual derailment coefficients at the timing that flange climbing occurs.