• Title/Summary/Keyword: force polygon

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Analysis of the Three-Roll Power Spinning Process by using the Method of Force Polygon Diagram (힘다각형선도법을 이용한 세롤에 의한 파워스피닝공정의 해석)

  • Yoo, Dong-Jin
    • Journal of the Korean Society for Precision Engineering
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    • v.2 no.3
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    • pp.47-58
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    • 1985
  • The study is concerned with the analysis of the required loads and torque in the Three-Roll Power Spinning Process by using the Method of Force Polygon Diagram. Experiments are carried out using pure lead billets at room temperature. The radial force, the axial force and the torque occurring during the process are calculated theoretically and are compared with the experimental data. An approximate load distribution is known by the Force Polygon Diagram.

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Preliminary Structural Form Planning for Suspension Bridge According to Force Flow (힘의 흐름을 따르는 현수교의 초기 구조형태계획)

  • Kim, Namhee;Koh, Hyun-Moo
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.33 no.4
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    • pp.1315-1326
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    • 2013
  • Geometric form of a suspension bridge that uses load-sensitive cables takes on not only resisting loads but also becoming a visually sensible shillouette. This study has proposed a preliminary structural form planning for a suspension bridge following force flow by adopting the two possibilities of the graphic statics. First, the force polygon allows alternative load paths for the same loading condition. Second, a new structural form for the newly developed load path can be constructed using the reciprocal principle that exits between a structure space and the corresponding force polygon. Major structural form parameters that affect both structural and aesthetic aspecs are first identified. The relationships between structural forms and the corresponding force polygons are then investigated for the identified parameters. Upon the investigation, a stepwise process is developed for a preliminary structural form planning for a suspension bridge. The proposed structural form planning method is general that can be easily expanded to generate design alternatives of similar form-active structural systems. It is also expected that this method will be used as an educational tool to explain the interrelationships between structural forms and their force flows.

Development of Visual Tools for Strut-Tie Model (스트럿 타이 모델개발을 위한 시각화 도구 개발)

  • Kim, Nam-Hee;Hong, Sung-Gul;Yeo, Deok-Hyun
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2008.04a
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    • pp.596-601
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    • 2008
  • This paper presents how to develop visual design tools for construction of strut-and-tie models(S (STM). STMs have shown internal force flows for dimensioning and proportioning of D-regions of reinforced concrete structures. In order to select an appropriate strut-and-tie model some interactive graphic tools are necessary to help designers compare alternatives by changing the geometry of initial STM. This study proposes to use force polygons representing the equilibrium state of STM. The change of STM dynamically shows change of force magnitudes by force polygon. Once the geometry of STM is determined the detailing design process is required in the next procedure.

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The Virtual Environment Control using Real-time Graphic Deformation Algorithm (실시간 그래픽 디포메이션 알고리즘을 이용한 가상환경젱어)

  • 강원찬;김남오;최창주
    • The Transactions of the Korean Institute of Electrical Engineers D
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    • v.53 no.5
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    • pp.309-314
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    • 2004
  • In the established virtual-reality system, although it is possible to transact a faculty of sensation and graphic in a single PC, virtual object forcibly treated with rigid body for the reason of the huge amount of calculation, and the number of polygon is restricted. Furthermore, there is some difficulty in the financial aspect and a program field, because the existing virtual-reality system needs at least two workstations or super computers. In this study, the new force-reflecting algorithm called as "Proxy" and a finite element method of Hyperion are applied to this system in order to transact in real-time. Consequently, though the number of polygon, which brings about an obstacle is increased in the real-time graphic transaction, this system makes it possible to transact in the real-time, not being influenced by the size of the virtual object.

Equilibrium Stress Mode Determination of Tensegrity Structure by CAD (CAD를 이용한 텐세그리티 구조물의 평형응력모드 결정법)

  • Kim, Jae-Yeol
    • Journal of Korean Association for Spatial Structures
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    • v.12 no.2
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    • pp.81-88
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    • 2012
  • Cable dome structures are composed of cables-masts and the cables should be in pre-tension since a structure without pre-tension is not stable. Under the pretension, self equilibrium stress state is the main characteristic of a cable dome structure. In this paper, a new method based on the basic principle of closed force polygon for equilibrium system is proposed for the determination of self-equilibrium mode of cable dome structure. The proposed method which is called geometric method has the unique characteristic of visualization of the force mode needed for maintenance of self-equilibrium. The basic theory for a self equilibrium of structure is that the summation of forces at each joint without any external load should be zero. The simplicity of the method which involves only drawing close polygon with the aid of suitable CAD software has been illustrated by means of a example. The results compared with mechanical calculation and existed method and shows good agreement.

Body Impedance Control for Walking Stabilization of a Quadrupedal Robot (4족 보행 로봇의 걸음새 안정화를 위한 몸체 임피던스 제어)

  • Lee, Soo-Yeong;Hong, Ye-Seon
    • The Transactions of the Korean Institute of Electrical Engineers D
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    • v.49 no.5
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    • pp.257-263
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    • 2000
  • One of the basic assumptions in the static gait design for a walking robot is that the weight of leg should be negligible compared to that of body, so that the total gravity center is not affected by swing of a leg. Based on the ideal assumption of zero leg-weight, conventional static gait has been simply designed for the gravity center of body to be inside the support polygon, consisting of each support leg's tip position. In case that the weight of leg is relatively heavy, however, while the gravity center of body is kept inside the support polygon, the total gravity center of walking robot can be out of the polygon due to weight of a swinging leg, which causes instability in walking. Thus, it is necessary in the static gait design of a real robot a compensation scheme for the fluctuation in the gravity center. In this paper, a body impedance control is proposed to obtain the total gravity center based on foot forces measured from load cells of a real walking robot and to adjust its position to track the pre-designed trajectory of the corresponding ideal robot's body center. Therefore, the walking stability is secured even in case that the weight of leg has serious influence on the total gravity center of robot.

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Shape Effects on Aerodynamic and Pedestrian-level Wind Characteristics and Optimization for Tall and Super-Tall Building Design

  • Kim, Yong Chul;Xu, Xiaoda;Yang, Qingshan;Tamura, Yukio
    • International Journal of High-Rise Buildings
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    • v.8 no.4
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    • pp.235-253
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    • 2019
  • This paper reviews shape optimization studies for tall and super-tall building design. Firstly, shape effects on aerodynamic and response characteristics are introduced and discussed. Effects of various configurations such as corner modifications, taper, setback, openings, and twists are examined. Comprehensive comparative studies on various configurations including polygon building models, and composite type building models such as corner-cut and taper, corner-cut and taper and helical, and so on, are also discussed under the conditions of the same height and volume. Aerodynamic characteristics are improved by increasing the twist angle of helical buildings and increasing the number of sides of polygon buildings, but a twist angle of $180^{\circ}$ and a number of sides of 5 (pentagon) seem to be enough. The majority of examined configurations show better aerodynamic characteristics than straight-square. In particular, composite type buildings and helical polygon buildings show significant improvement. Next, shape effects on pedestrian-level wind characteristics around tall and super-tall buildings are introduced and discussed. Corner modification buildings show significant reductions in speed-up areas. On the other hand, setback and tapered models with wider projected widths near the ground show adverse effects on pedestrian-level wind characteristics.

Multi-response optimization of crashworthiness parameters of bi-tubular structures

  • Vinayagar, K.;Kumar, A. Senthil
    • Steel and Composite Structures
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    • v.23 no.1
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    • pp.31-40
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    • 2017
  • This article aims at presenting multi objective optimization of parameters that affect crashworthiness characteristics of bi-tubular structures using Taguchi method with grey relational analysis. To design the experiments, the $L_9$ orthogonal array has been used and based on that, the inner tubes have been fabricated by varying the three influence factors such as reference diameter, length difference and numbers of sides of the polygon with three levels, but all the outer cylinders have the same diameter and length 90 mm and 135 mm respectively. Then, the tailor made bi-tubular steel structures were subjected into quasi static axial compression. From the test results it is found that the crushing behaviors of bi-tubular structures with different combinations were fairly significant. The important responses (crashworthiness indicators) specific energy absorption and crush force efficiency have been evaluated from load - displacement curve. Finally optimal levels of parameters were identified using grey relational analysis, and significance of parameters was determined by analysis of variance. The optimum crashworthiness parameters are reference diameter 80 mm, length difference 0 mm and number of sides of polygon is 3, i.e., triangle within the selected nine bi-tube combinations.

Development of PC-Based 6DOF Force Display System (PC기반의 6자유도 촉각장치의 개발)

  • Shin, Suck-Doo;Kang, Won-Chan;Kim, Dong-Ok;Kim, Won-Bae;Kim, Young-Dong
    • The Transactions of the Korean Institute of Electrical Engineers D
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    • v.50 no.5
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    • pp.211-217
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    • 2001
  • In this paper, we have developed the 6 DOF force display system to be based on the single PC. The system is composed of the force display device, the force reflecting rendering algorithm and the high-speed controller. The previous systems had a problem, that must adopt high performance workstation or 2-PC in order to control the graphics speedily and stably. In this paper, it is possible to improve the problem as to develop its exclusive controller and new rendering algorithm. The proposed new rendering algorithm is based on the Proxy algorithm, which can convert information of the position, the velocity, and the haptic information into the force-data. Especially, as to use the proxy algorithm, we can construct dynamical virtual-environment with the elasticity, the viscosity, the mass, and the friction force. As the result of the experiment, we found that our system has much superior characteristics than some other haptic interfaces, because it can control of 30,000 polygon model constructed virtual object with 1[kHz] haptic interrupt cycle and 20[Hz] graphic interrupt cycle in the single PC based system.

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Study of the effect of varying shapes of holes in energy absorption characteristics on aluminium circular windowed tubes under quasi-static loading

  • Baaskaran, N;Ponappa, K;Shankar, S
    • Structural Engineering and Mechanics
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    • v.70 no.2
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    • pp.153-168
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    • 2019
  • In this paper, energy absorption characteristics of circular windowed tubes with different section shapes (circular, ellipse, square, hexagon, polygon and pentagon) are investigated numerically and experimentally. The tube possesses the same material, thickness, height, volume and average cross sectional area which are subjected under axial and oblique quasi-static loading conditions. Numerical model was constructed with FE code ABAQUS/Explicit, the obtained outcome of simulation is in good matching with the experimental data. The energy absorbed, specific energy absorption, crash force efficiency, peak and mean loads along with the collapse modes with their initiation point of simple and windowed tubes were evaluated. The technique for order of preference by similarity ideal solution (TOPSIS) approach was employed for assessing their overall crushing performances. The obtained results confirm that efficacy of crash force indicators have improved by introducing windows and tubes with pentagonal and circular windows achieves the maximum ranking about 0.528 and 0.517, it clearly reveals the above are best window shapes.