• Title/Summary/Keyword: Edge Beam

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Model Cut-edge Formed on Zinc Coated Steels by Laser Machining and Its Corrosion Behavior

  • Sakairi, Masatoshi;Kageyama, Akihiro;Kikuhchi, Tatsuya
    • Corrosion Science and Technology
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    • v.9 no.1
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    • pp.29-33
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    • 2010
  • Laser machining technique, which is used focusing pulse YAG laser beam irradiation was applied to form area ratio controlled model cut-edge on pre painted Zn coated steels. A corrosion behavior of formed model cut-edge was investigated by rest potential measurement in 1 mol $m^{-3}$ NaCl with and without 0.5 kmol $m^{-3}$ $H_3BO_4$/0.05kmol$m^{-3}$ $Na_2B_4O_7$. The rest potential showed almost constant value with fluctuations. The amplitude of fluctuations increased with exposed area of steel surface. White corrosion products of zinc oxide and simonkollite was formed after the experiments at the formed model cut-edge.

The analytical solution for buckling of curved sandwich beams with a transversely flexible core subjected to uniform load

  • Poortabib, A.;Maghsoudi, M.
    • Structural Engineering and Mechanics
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    • v.52 no.2
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    • pp.323-349
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    • 2014
  • In this paper, linear buckling analysis of a curved sandwich beam with a flexible core is investigated. Derivation of equations for face sheets is accomplished via the classical theory of curved beam, whereas for the flexible core, the elasticity equations in polar coordinates are implemented. Employing the von-Karman type geometrical non-linearity in strain-displacement relations, nonlinear governing equations are resulted. Linear pre-buckling analysis is performed neglecting the rotation effects in pre-buckling state. Stability equations are concluded based on the adjacent equilibrium criterion. Considering the movable simply supported type of boundary conditions, suitable trigonometric solutions are adopted which satisfy the assumed edge conditions. The critical uniform load of the beam is obtained as a closed-form expression. Numerical results cover the effects of various parameters on the critical buckling load of the curved beam. It is shown that, face thickness, core thickness, core module, fiber angle of faces, stacking sequence of faces and openin angle of the beam all affect greatly on the buckling pressure of the beam and its buckled shape.

Laser Beam Irradiation Strengthening for Weight Reduction of Automobile Bumper Beam (I) (자동차 범퍼빔 경량화를 위한 레이저 빔 조사 강화(I))

  • Suh, Jeong;Lee, Jae-Hoon;Oh, Sang-Jin;Lee, Moon-Yong;Lee, Gyu-Hyun
    • Transactions of the Korean Society of Automotive Engineers
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    • v.10 no.5
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    • pp.228-234
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    • 2002
  • The CO$_2$ laser beam irradiation strengthening of 35kgf/mm$_2$ grade steel sheet is investigated to reduce the weight of bumper beam. The increase of tensile strength is dominated by the number of fully penetrated melting lines. The optimal laser irradiation pattern is obtained by 3-point bending test of hat-type specimens. Laser should be irradiated not only on the center specimen densely in the width direction, but also on the edge densely in the longitudinal direction. Local laser strengthening may be effective for the weight reduction of automobile bumper beam.

Correction Method on Mismatched Posterior Edge of Medial and Lateral Tangential Fields for Three Fields Techniques in Breast Cancer (유방암 환자의 삼문 조사 시 내외측 접면 조사야의 Posterior Edge의 어긋남의 교정)

  • Kim Hun-Jung;Loh John JK;Kim Woo-Cheol;Park Sung-Young
    • Radiation Oncology Journal
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    • v.21 no.2
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    • pp.174-181
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    • 2003
  • Purpose: The target volume for the three field technique in breast cancer include the breast tangential and supraclavicular areas. The techniques rotating the gantry and couch angles, to match these two areas, will geometrically produce mismatching of the posterior edge between the medial and lateral tangential beams. This mismatch was confirmed by film dosimetry and three-dimensional computer planning. The correction methods of this mismatching were studied in this article. Materials and Methods: After the supraclavicular field was simulated using a half beam block and the medial and lateral tangential fields, by the rotation of the couch and gantry, we compared the following two methods to correct the mismatch. The first method was the rotation of coillmator until a line drawn on the posterior edge of tangential beams before the rotation of couch aligned the line drawn on the posterior edge after the rotation. The second method was the rotation of collimator according to the formula developed by the author as follows; Co=$2sin^{-1}${$sin\{theta}\{cdot}sin(C/2)$} (Co: collimator angle, $\theta$: angle between tangential beam and table, C: couch angle) Results: The film dosimetry showed the mismatching of posterior edges of the medial and lateral tangential fields prior to the rotation of collimator, while the posterior edges matched well after the rotation of collimator according to the formula. The three-dimensional computer plan also showed that the posterior edges matched well after the rotation of collimator accordingly. The DVH of the ipsilateral lung with the proper rotation of collimator angle was better than that without the rotation of collimator angle. Conclusion: The mismatching of the posterior edges of the medial and lateral tangential fields can be recognized on the three fileld technique in breast irradiation when the gantry and couch are simultaneously rotated and can be corrected with the proper rotation of the collimator angle. The radiation dose to the ipsilateral lung could be lowered with this technique.

Response of a completely free beam on a tensionless Pasternak foundation subjected to dynamic load

  • Celep, Z.;Guler, K.;Demir, F.
    • Structural Engineering and Mechanics
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    • v.37 no.1
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    • pp.61-77
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    • 2011
  • Static and dynamic responses of a completely free elastic beam resting on a two-parameter tensionless Pasternak foundation are investigated by assuming that the beam is symmetrically subjected to a uniformly distributed load and concentrated load at its middle. Governing equations of the problem are obtained and solved by paying attention on the boundary conditions of the problem including the concentrated edge foundation reaction in the case of complete contact and lift-off condition of the beam ina two-parameter foundation. The nonlinear governing equation of the problem is evaluated numerically by adopting an iterative procedure. Numerical results are presented in figures to demonstrate the non-linear behavior of the beam-foundation system for various values of the parameters of the problem comparatively by considering the static and dynamic loading cases.

Effect of beam slope on the static aerodynamic response of edge-girder bridge-deck

  • Lee, Hoyeop;Moon, Jiho;Chun, Nakhyun;Lee, Hak-eun
    • Wind and Structures
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    • v.25 no.2
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    • pp.157-176
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    • 2017
  • 2-edge box girder bridges have been widely used in civil engineering practice. However, these bridges show weakness in aerodynamic stability. To overcome this weakness, additional attachments, such as fairing and flap, are usually used. These additional attachments can increase the cost and decrease the constructability. Some previous researchers suggested an aerodynamically stabilized 2-edge box girder section, giving a slope to the edge box instead of installing additional attachments. However, their studies are limited to only dynamic stability, even though static aerodynamic coefficients are as important as dynamic stability. In this study, focus was given to the evaluation of static aerodynamic response for a stabilized 2-edge box girder section. For this, the slopes of the edge box were varied from $0^{\circ}$ to $17^{\circ}$ and static coefficients were obtained through a series of wind tunnel tests. The results were then compared with those from computational fluid dynamics (CFD) analysis. From the results, it was found that the drag coefficients generally decreased with the increasing box slope angle, except for the specific box slope range. This range of box slope varied depending on the B/H ratio, and this should be avoided for the practical design of such a bridge, since it results in poor static aerodynamic response.

Reverse Engineering of Compound Surfaces on the Machine Tool using a Vision Probe (비전 프로브를 이용한 기상에서의 복합곡면의 역공학)

  • 김경진;윤길상;초명우;권혁동;서태일
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2002.05a
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    • pp.287-292
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    • 2002
  • This paper presents a reverse engineering method for compound surfaces using vision system. A CNC machining center is used as a measuring station, which is equipped with slit beam generator and vision probe. Since obtained data using slit beam or laser scanner may have much data loss along the edge of compound surfaces, an algorithm is presented in this study to recover missing geometric data at such region. First, b-spline interpolation is applied to extract edge information of the surface, and as a next step, b-spline approximation is applied to recover the missing geometric data. Finally, b-spline skinning method is applied to regenerate the surface information. Appropriate simulation and experimental works are preformed to very the effectiveness of the proposed methods.

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Free vibration analysis of multiple open-edge cracked beams by component mode synthesis

  • Kisa, M.;Brandon, J.A.
    • Structural Engineering and Mechanics
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    • v.10 no.1
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    • pp.81-92
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    • 2000
  • This study is an investigation of the effect of cracks on the dynamical characteristics of a cantilever beam, having multiple open-edge transverse cracks. The flexibilities due to crack have been identified for several crack depths and locations. In the study the finite element method and component mode synthesis methods are used. Coupling the components is performed by a flexibility matrix taking into account the interaction forces. Each component is modelled by cantilever beam finite elements with two nodes and three degrees of freedom at each node. The results obtained lead to conclusion that, by using the drop in the natural frequencies and the change in the mode shapes, the presence and nature of cracks in a structure can be detected. There is some counter-evidence, however, that the effects due to multiple cracks may interact to make detection more difficult than for isolated cracks.

Force identification by using specific forms of PVDF patches

  • Chesne, Simon;Pezerat, Charles
    • Smart Structures and Systems
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    • v.15 no.5
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    • pp.1203-1214
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    • 2015
  • This paper deals with the experimental validation of the use of PVDF Patches for the assessment of spatial derivatives of displacement field. It focuses more exactly on the shear Force Identification by using Specific forms of PVDF patcHes (FISH) on beams. An overview of the theoretical approach is exposed. The principle is based on the use of the weak form of the equation of motion of the beam which allows the shear forces to be extracted at one edge of the sensor when this last has a specific form. The experimental validation is carried out with a cantilever steel beam, excited by a shaker at its free boundary. The validation consists in comparing the shear force measured by the designed sensor glued at the free edge and the directly measured force applied by the shaker. The sensor is made of two patches, called the "stiffness" patch and the "mass" patch. The use of both patches allows one to identify correctly the shear force on a large frequency domain. The use of only the stiffness patch is valid in the low frequency domain and has the advantage to have a frequency-independent gain that allows its use in real time.

Localization of Acoustic Sources on Wind Turbine by Using Beam-forming Techniques (빔-형성 기법을 이용한 풍력 터빈 음원의 국부화)

  • Lee, Gwang-Se;Shin, Su-Hyun;Cheong, Cheol-Ung;Jung, Sung-Soo
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.19 no.8
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    • pp.809-815
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    • 2009
  • The previous work(Cheong et al., 2006) where the characteristics of acoustic emissions of wind turbines has been investigated according to the methods of power regulation, has showed that the acoustic power of wind turbine using the stall control for power regulation is more correlated with the wind speed than that using the pitch control. In this paper, basically extending this work, the noise generation characteristics of large modern upwind wind turbines are experimentally indentified according to the power regulation methods. To investigate the noise generation mechanisms, the distribution of noise sources in the rotor plane is measured by using the beam-forming measurement system(B&K 7768, 7752, WA0890) consisting of 48 microphones. The array results for the 660 kW wind turbine show that all noise is produced during the downward movement of the blades. This result show good agreement with the theoretical result using the empirical formula with the parameters: the convective amplification; trailing edge noise directivity; flow-speed dependence. This agreement implies that the trailing edge noise is dominant over the whole frequency range of the noise from the 660 kW wind turbine using the pitch control for power regulation.