• Title/Summary/Keyword: plate equation

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Evaluation of Corrosion Thickness Loss of Temporary Steel Members Exposed to A Subway Construction Site (지하철 공사현장 환경하의 가시설 강재의 부식두께감소량 추정)

  • Kim, In Tae;Jeon, Sang Hyuck;Hur, Jung Ok;Cheung, Jin Hwan
    • Journal of Korean Society of Steel Construction
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    • v.21 no.3
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    • pp.301-310
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    • 2009
  • Steel has been widely used as a material in temporary structures. Corrosion attack often reduces the long-term durability of temporary steel members that are not protected from corrosion. In designing temporary steel structures, it is difficult to evaluate their long-term durability, since the thickness loss of steel members is not clear. In this study, laboratory and field exposure corrosion tests were performed on structural steel plate specimens, and the loss of thickness of specimens that were exposed to a subway construction site for 11 months and of specimens that were exposed to environments with controlled humidity and calcium chloride for six months were measured. Finally, a thickness loss equation was formulated based on the environmental conditions and the testing periods.

The Simulation and Experiment of Flexible Media with High Exit Velocity (고속의 출구속도를 가지는 유연매체의 거동해석 및 실험)

  • Hong, Sung-Kwon;Jee, Jung-Geun;Jang, Yong-Hoon;Park, No-Cheol;Park, Young-Pil
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2006.05a
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    • pp.380-383
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    • 2006
  • The media transport system is used in a printer, a ATM(Automated Tellor Machine), and so on. The media transport system has many problems through miniaturization and rapid transportation of these machines. In the paper feeding mechanism, it is important to feed the sheet without jamming under any conditions. To avoid sheet jamming, first we need to predict the behavior of the sheet exactly. In this paper, the analysis of media behavior is based on J. Stolte's studies. In all of OA machines, a flexible beam or plate is pushed from the channel. The motion may be constrained by guides. This leads to a transient and geometrically nonlinear problem. The behavior of paper is simulated by dynamic elastica theory. The shape of guide is represented by parametric cubic curve. But J. Stolte's studies did not considered contact condition between sheet and guide. So Klarbring's Model. will be applied. And the analysis of flexible media has to include aerodynamic effect for more exact behavior analysis, because the flexible media can be deformed drastically by a little force. Therefore aerodynamic force must be applied to the governing equation. Lastly, the simulation of this model is performed, and the experiment is performed for verification of this model. The experimental results of low exit velocity are consistent with the simulation results, however experimental results of high exit velocity do not agree well with analytical results. The reason is that there may be other effects like nip Phenomena

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Drying of Red Ginseng by Flat-Plate Solar Collector (평면식(平面式) 태양열집열기(太陽熱集熱機)를 이용(利用)한 홍삼건조(紅蔘乾燥))

  • Chang, Kyu-Seob;Kim, Sang-Dal;Hong, Soon-Keun;Yoon, Han-Kyo
    • Applied Biological Chemistry
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    • v.25 no.3
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    • pp.111-118
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    • 1982
  • A closed solar collector drying system by water exchange was evaluated for the drying of ginseng. The thermal efficiency of solar collector, drying efficiency, drying characteristics and product quality were investigated. The drying period was reduced by one-thirds in comparison with typical method. The maximum and minimum thermal efficiency of the solar collector during drying period were 14.42%, and 4.73%, respectively. The drying efficiency of solar collector and control system showed 28.34%, and 13.45%, respectively; net drying efficiency being 14.8%. The drying rate curve of red ginseng showed only falling rate period, and its equation was $Y=50.7023t.^{-0.4138}$ The brown color intensity of red ginseng was higher in solar collector drying system than in typical method, and reductivity by diphenyl picryl hydrazil solution in red ginseng extract showed similar result to brown color intensity.

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$J_{1C}$ and J-integral Behavior of Low-Carbon Steel using Double Edge Tension Specimen (양쪽 크랙 인장시험편을 이용한 저탄소강의 $J_{1C}$ 및 J적분 거동)

  • 고성위
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.21 no.2
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    • pp.151-156
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    • 1985
  • In this paper, the plane stress fracture toughness of cold rolled 4.5mm thick SS41 steel plate was investigated for various crack ratios respectively in case of base metal, normalized and annealed heat-treated specimens using the method of J-integral. The specimen geometry used was double edge tension (DET) specimen. The experiments were performed on an Instron machine and all the crack lengths were measured by travelling microscope. The plane stress fracture toughness obtained by the method of Rice equation was J sub(1C)=22.8kgf/mm for the base metal, j sub(1C)-24.7kgf/mm for the normalized specimen and J sub(1C)=26.9 kgf/mm for the annealed. The J-integral computed at the limit load was found unsuitable for fracture toughness determination, because of large variation depending on the crack ratio.

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Flow Characteristics inside a Throttle Valve Used to Control the Intake Air Flow in Engines (엔진의 흡기 공기량 조절용 스로틀 밸브에서의 유동 특성)

  • Kim, Sung-Cho;Kim, Cheol
    • Transactions of the Korean Society of Automotive Engineers
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    • v.7 no.8
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    • pp.91-98
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    • 1999
  • This paper describes the air flow characteristics inside the throttle valve. Tow-dimensional steady incompressible Navier-Strokes equation are solved numerically with embedding the conceopt of the artificial compressibility and adopting the Baldwin-Lomax turbulence model. With varying the valve opening angles(the Reynolds number )such as 15$^{\circ}$(5000) , 45$^{\circ}$(3000) , 75$^{\circ}$(7000) and 90$^{\circ}$(10000), respectively. tow cases, with a valve shaft and without one, are analysed. The pressure loss between the entrance and exit is severe at 15$^{\circ}$, 100 times as larger as that of 90$^{\circ}$ case, which also depends much on the existece of the valve shaft. The counter rotating vortices are formed over the valve plate with the shaft at only 75$^{\circ}$. They are smally and very large scale in front and back of the valve shaft , respectively. The velocity profiles of 15$^{\circ}$ and 90$^{\circ}$ at the exit are almost symmetric to the horizontal center line, however, the symmetricity is no longer maintained at 45$^{\circ}$ and 75$^{\circ}$ , and in addition, the flow at 75$^{\circ}$ is enforced a lot below center line. The pressure distribution on the walls is largely changed near the valve shaft, and its magnitude becomes great as the valve angle decreases.

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Thrust Force Characteristics Analysis of Linear Induction Motor Considering Airgap variation for Railway Transit (공극변화를 고려한 철도차량용 선형 유도전동기 특성 연구)

  • Lee, Byung-Song
    • Proceedings of the KSR Conference
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    • 2008.06a
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    • pp.1903-1908
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    • 2008
  • This paper presents a characteristics of linear induction motor considering airgap variation for railway transit in order to achieve high performance of the vehicle. The operating principle of a LIM(Linear induction motor) is identical to a rotary induction motor. Space-time variant magnetic fields are generated by the primary part across the airgap and induce the electro-motive force(EMF) in the secondary part, a conducting sheet. This EMF generates the eddy currents, which interact with the airgap flux and so produce the thrust force known as Loren's force. Even though the operating principal is exactly same as a rotary motor, the linear motor has a finite length of the primary or secondary parts and it causes static and dynamic end-effect which is the discontinuous airgap flux phenomenon. This end-effect causes the deterioration of the system performance, especially in high-speed operation. Another problem is that construction tolerance restricts the minimum airgap in order to prevent a collision between the primary part and the secondary reaction plate. More over, as the airgap length is getting smaller, the attraction force between the primary part and secondary parts is getting larger dramatically and the attraction force would be another friction against propulsion. Therefore, it is necessary to figure out the characteristics of linear induction motor considering airgap variation in order to achieve high performance of the vehicle. The dynamic model of LIM taking into account end-effects is derived. Then the modified mechanical load equation considering the effect of the attraction and thrust force according to the airgap variation is analyzed. The simulation results are presented to show the effect of the LIM according to the airgap variation.

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Analysis of Laminated Composite Skew Plates with Uniform Distributed Load by Finite Difference Method (유한차분법에 의한 등분포 상재하중하 적층 복합재 경사판 해석)

  • Park, Weon Tae;Choi, Jae Jin;Chang, Suk Yoon
    • Journal of Korean Society of Steel Construction
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    • v.12 no.3 s.46
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    • pp.291-302
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    • 2000
  • In recent years the development of high modulus, high strength and low density boron and graphite fibers bonded together has brought renewed interestes in structural elements. When a plate with arbitrarily oriented layers and clamped boundary conditions is subjected to uniform loading, it is difficult to analyze and apply, compared with isotropic and orthotropic cases. Therefore the numerical methods, such as finite difference method or finite element method, should be emloyed to analyse such problems. In this study the finite difference technique is used to formulate the bending analysis of symmetric composite laminated skew plates. When this technique is used to solve the problem, it is desirable to reduce the order of the derivatives in order to minimize the number of the pivotal points involved in each equation. The 4th order partial differential equations of laminated skew plates are converted to an equivalent three of 2nd order partial differential equations with three dependant variables.

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Flow Properties of Red Flower Cabbage Pigment Solutions (꽃양배추 색소 추출액의 유동특성)

  • Rhim, Jong-Whan;Lee, Jung-Ju
    • Korean Journal of Food Science and Technology
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    • v.33 no.2
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    • pp.221-225
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    • 2001
  • Flow properties of red flower cabbage pigment solutions were determined over a wide range of temperatures ($20-50^{\circ}C$) and soluble solid concentrations (1-65%) using a cone and plate rotational viscometer. Flow properties of the pigment solutions were adequately described by the simple power law model. Within the tested ranges of concentration, temperature and shear rate, the flow behavior index (n) and the consistency index (K) of the solutions were in the ranges of 0.841-0.998 and $0.008-31.525\;Pa{\cdot}s^n$, respectively. The effect of temperature on the apparent viscosity of the solutions followed an Arrhenius type relationship. Activation energy of flow varied from 9.36 to 52.48 kJ/mol depending on the solid concentration and shear rate. The combined effect of temperature and concentration on the apparent viscosity at the shear rate of $100\;s^{-1}$ could be represented by a single equation as ${\ln}\;{\eta}_a\;=\;6.11\;-\;3103.94(1/T)\;-\;0.03C$.

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Vibration of Rectangular Plates (직사각형판(直四角形板)의 진동해석(振動解析))

  • Keuck-Chun,Kim;Tae-Young,Chung
    • Bulletin of the Society of Naval Architects of Korea
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    • v.14 no.1
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    • pp.1-10
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    • 1977
  • The major objects of this report are to supplement data of natural frequencies of thin elastic rectangular plates to the available data, and to give an experimental verification for natural frequencies obtained by Rayleigh-Ritz method, the generation set of which are eigenfunctions of Euler beams. For the first object the following five models, for which data only for the fundamental mode or data only for square plates are available, are adopted; (1) two opposed edges are clamped and the other two opposed edges simply supported (C-C, S-S), (2) one edge is simply supported and the other three edges clamped (C-C, C-S), (3) one edge is free and the other three edges clamped (C-C, C-F), (4) two adjacent edges are clamped and the other two adjacent edges free (C-F, C-F). For the (C-C, S-S) model the frequency equation obtained with the mode shapes assumed as of a single trigonometric series is solved. And for the other four models Rayleigh-Ritz method taking eigenfunctions of Euler beams as the generating set is applied. The numerical examples are obtained up to the fourth, the fifth or the sixth order depending on the range of the aspect ratio (0.1-10.0). The number of terms in the generating set for Rayleigh-Ritz method is fifteen for all models. For the experiment three models made of 3.2mm thickness mild steel plate for general structure use were prepared in following size; $300mm{\times}600mm,\;600mm{\times}600mm\;and\;900mm{\times}600mm$. Their boundary conditions are made to fit (C-C, C-F) condition. From the experiment mechanical impedance curves based on the frequency response method were obtained together with phase relation diagrams. The experimental data are resulted in good conformity to calculated values.

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A Numerical Study of the Residual Hydrogen Concentration in the Weld Metal (용접금속 잔류수소농도의 수치해석 연구)

  • Yoo, Jinsun;Ha, Yunsok;S.R., Rajesh
    • Journal of Welding and Joining
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    • v.34 no.6
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    • pp.42-46
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    • 2016
  • Hydrogen assisted cracking (HAC) is one of the most complicated problem in welding. Huge amount of studies have been done for decades. Based on them, various standards have been established to avoid HAC. But it is still a chronic problem in industrial field. It is well known that the main causes of the hydrogen crack are residual stress, crack susceptible micro structures and a certain critical level of hydrogen concentration. Even though the exact generating mechanism is unclear till today, it has been reported that the hydrogen level in the weld metal should be managed less than a certain amount to prevent it. Matsuda studied that the residual hydrogen level in the weld metal can be varied even if the initial hydrogen content is same. It is also insisted in this report that the residual hydrogen concentration is in stronger correlation with hydrogen crack than the initial hydrogen content. But, in practical point of view, the residual hydrogen is still hard to consider because measuring hydrogen level is time and cost consuming process. In this regard, numerical analysis is the only solution for considering the residual hydrogen content. Meanwhile, Takahashi showed the possibility of predicting the residual hydrogen by a rigorous FE analysis. But, few commercial software suitable for solving the weld metal hydrogen has been reported yet. In this study, two dimensional thermal - hydrogen coupled analysis was developed by using the commercial FE software MARC. Since the governing equation of the hydrogen diffusion is similar to the heat transfer, it is shown that the heat transfer FE analysis in association with hydrogen diffusion property can be used for hydrogen diffusion analysis. A series of simulation was performed to verify the accuracy of the model. For BOP (Bead-On-Plate) and the multi-pass butt welding simulations, remaining hydrogen contents in the weld metal is well matched with measurements which are referred from Kim and Masamitsu.