• Title/Summary/Keyword: Length of a plate

Search Result 1,024, Processing Time 0.029 seconds

Fibre composite railway sleeper design by using FE approach and optimization techniques

  • Awad, Ziad K.;Yusaf, Talal
    • Structural Engineering and Mechanics
    • /
    • v.41 no.2
    • /
    • pp.231-242
    • /
    • 2012
  • This research work aims to develop an optimal design using Finite Element (FE) and Genetic Algorithm (GA) methods to replace the traditional concrete and timber material by a Synthetic Polyurethane fibre glass composite material in railway sleepers. The conventional timber railway sleeper technology is associated with several technical problems related to its durability and ability to resist cutting and abrading action of the bearing plate. The use of pre-stress concrete sleeper in railway industry has many disadvantages related to the concrete material behaviour to resist dynamic stress that may lead to a significant mechanical damage with feasible fissures and cracks. Scientific researchers have recently developed a new composite material such as Glass Fibre Reinforced Polyurethane (GFRP) foam to replace the conventional one. The mechanical properties of these materials are reliable enough to help solving structural problems such as durability, light weight, long life span (50-60 years), less water absorption, provide electric insulation, excellent resistance of fatigue and ability to recycle. This paper suggests appropriate sleeper design to reduce the volume of the material. The design optimization shows that the sleeper length is more sensitive to the loading type than the other parameters.

Influence of the Unsteady Wake on the Flow and Heat Transfer in a Linear Turbine Cascade (비정상 후류가 선형터빈익렬의 유동 및 열전달에 미치는 영향에 관한 연구)

  • Yun, Sun-Hyeon;Sim, Jae-Gyeong;Kim, Dong-Geon
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.25 no.2
    • /
    • pp.164-170
    • /
    • 2001
  • The influence of unsteady wake on the flow and heat transfer characteristics in a four-vane linear cascade was experimentally investigated. The unsteady wake was generated with four rotating rectangular plates located upstream of the cascade. Tested inlet Reynolds number based on chord length was set to 66,000 by controlling free-stream velocity. A hot-wire anemometer system was employed to measure turbulent velocity components. For the convective heat transfer coefficients measurement on turbine blade surface, thermochromic liquid crystal and gold film Intrex were used. It was found that the unsteady wake enhances the turbulent motion in the cascade passage and accordingly promotes the development and transition of boundary layer. It was found that the heat transfer coefficients on the blade surface increase as the plate rotating speed increases. However, the increasing of heat transfer coefficients is not significant in the case that Strouhal number is higher than 0.503.

Improvement of the flow around airfoil/flat-plate junctures by optimization of the leading-edge fence (날개-평판 접합부에서의 날개 앞전 판 최적화를 통한 유동특성 향상)

  • Cho, Jong-Jae;Kim, Kui-Soon
    • Journal of the Korean Society for Aeronautical & Space Sciences
    • /
    • v.37 no.9
    • /
    • pp.829-836
    • /
    • 2009
  • 3-Dimensional flow which is represented by horseshoe vortex is generated as a type of secondary flow about the main flow. As well, it causes the flow loss. The present study deals with the leading edge fence shape on a wing-body junction to decrease a horseshoe vortex, one of the main factors to generate the secondary flow losses. The shape of leading-edge fence was optimized with the design variables of the installed height, length, width, and thickness of the fence as the design variables. Approximate optimization design method is used as the optimization. The study was investigated using $FLUENT^{TM}$ and $iSIGHT^{TM}$. Total pressure coefficient of the optimized design case was decreased about 7.5 % compare to the baseline case.

Study on Maneuvering Characteristics of Submerged Body by Changing Its Design Parameters (몰수체 형상 설계인자에 따른 조종특성 연구)

  • Jeon, MyungJun;Yoon, Hyeon Kyu;Hwang, Junho;Cho, Hyeon Jin
    • Journal of Ocean Engineering and Technology
    • /
    • v.31 no.2
    • /
    • pp.155-163
    • /
    • 2017
  • Submerged bodies moving underwater behave differently based on their type and assigned mission. This paper describes the dynamic characteristics, including the stability, turning ability, and operational ability, of submerged bodies in relation to design parameters such as the tail cone angle, shape of the control plate, and length of the parallel middle body. A submerged body operated in other countries is adopted as a reference for the dynamic characteristics, its principal dimensions and the shape of the bare hull and appendages are used for comparison. This paper suggests a few candidate hull forms based on changes in the typical design parameters. Finally, the dynamic characteristics for these candidate hull forms are defined.

The effect of a water exercise on gait characteristics in the elderly post stroke patients

  • Lim, Hee-Sung;Lee, Suk-Min
    • Physical Therapy Rehabilitation Science
    • /
    • v.1 no.1
    • /
    • pp.17-21
    • /
    • 2012
  • Objective: To investigate the effect of long-term water exercise on gait parameters in the elderly post stroke patients. Design: One group pretest-posttest design. Methods: Twenty elderly post stroke patients (age: $56.5{\pm}10.1$ years, height: $168.6{\pm}5.8cm$, body mass: $69.3{\pm}6.9kg$, handicapped level: $2.5{\pm}0.8$) participated in this study. Participants took part in gait training of 1 hour per day, three days per week, for three months. Participants' gaits were analyzed to find the effect of 3 months water exercise by a 3-D motion analysis with 8 infrared camera and 1 force plate (sampling frequency: 100 and 1,000 Hz, respectively). A paired t-test was used to find the significance with significant level as 0.05. Results: Gait velocity, step length & step width significantly increased, and asymmetric index for gait parameters significantly decreased after the water exercise (p<0.05). Conclusions: The water exercise effectively affect on patients' gait ability and electromyography analysis will be needed further study.

  • PDF

Strength Prediction Model of Interior Flat-Plate Column Connections according to Design Parameters (설계변수에 따른 플랫플레이트-기둥 접합부의 강도산정모형)

  • Lee, Do-Bum;Park, Hong-Gun;Lee, Li-Hyung
    • Journal of the Korea Concrete Institute
    • /
    • v.18 no.3 s.93
    • /
    • pp.405-414
    • /
    • 2006
  • In the present study, a numerical analysis was performed for interior connections of continuous flat plate to analyze the effect of design parameters such as column section shape, gravity load and slab span on the behavioral characteristics of the connections. For the purpose, a computer program for nonlinear FE analysis was developed, and the validity was verified. Through the parametric study, the variations of shear stress distribution around the connection were investigated. According to the result of numerical analysis, as the length of the cross section of column in the direction of lateral load increases and gravity load increases, the effective area and the maximum shear strength providing the torsional resistance decrease considerably. And as the slab span loaded with relatively large gravity load increases, the negative moment around the connection increases and therefore the strength of connection against unbalanced moment decreases. By considering the effect of design parameters on the strength of the connections, the effective shear strength to calculate the torsional moment capacity of connection was proposed and the effectiveness of the proposed shear strength was verified.

Characteristics of HTS Tube Depending on Chemical Compositions

  • Jung, Seung-Ho;Jang, Guneik
    • Progress in Superconductivity and Cryogenics
    • /
    • v.5 no.1
    • /
    • pp.27-30
    • /
    • 2003
  • The Bi2212 based HTS tubes with 4 different compositions, Bi:Sr:Ca:Cu = 2.0:2.0:1.0:2.0, 2.1:2.0:1.0:2.0,2.2:1.8:1.0:2.0 and 2.2:1.8.1.0.2:2 with 10% of SrSO$_4$ were studied. For tube fabrication the optimum range of melt temperatures and preheating temperature and time for mold were 105$0^{\circ}C$~110$0^{\circ}C$ and 55$0^{\circ}C$ for 30min respectively. The mold rotating speed was 1000rpm. Typical tube dimension was 30/24mm in outside/inside diameter and 60mm in length. A tube was annealed at 84$0^{\circ}C$ for 40 hours in oxygen atmosphere. The plate like grains more than 20${\mu}{\textrm}{m}$ were well developed along the rotating direction of mold regardless of initial chemical compositions. The specimen with Bi2212 composition exhibited $T_c$ of 83K while the specimen with other compositions are lower than 60K. The measured $I_c and J_c$ at 77K(B = 0T) in Bi2212 composition were about 80A and 266A/$\textrm{cm}^2$.

Buckling Characteristic of Non-Circular Closed Composite Shells (비원형 폐합쉘의 좌굴특성)

  • Park, Won-Tae;Chun, Kyoung-Sik
    • Journal of the Korean Society for Advanced Composite Structures
    • /
    • v.1 no.2
    • /
    • pp.36-43
    • /
    • 2010
  • In this study, the buckling loads and mode shapes characteristic of circular and non-circular(elliptical) closed composite shells were analyzed. To analyses the buckling behaviors, we develop and report an improved generalized shell element called 4EAS-FS through a combination of enhanced assumed strain and the substitute shear strain fields. A flat shell element has been developed by combining membrane element with drilling degree-of-freedom and a plate bending element. The combined influences of length, thicknesses, cross-sectional parameters, and fiber-angle on the critical buckling loads and mode shapes of circular and non-circular(elliptical) closed shells are examined.

  • PDF

Wide Beam Optical System for the Laser Materials Processing (레이저 재료 가공을 위한 광폭빔 광학 장치)

  • 김재도;조응산;전병철
    • Laser Solutions
    • /
    • v.1 no.1
    • /
    • pp.24-29
    • /
    • 1998
  • A new wide laser beam optical system for the laser materials processing has been developed with a polygonal mirror. It consists of polygonal mirror and cooling part that prevents the surface of rotating polygonal mirror from damage by heat. The polygonal minors have been designed and made as 24 and 30 facets in pyramid type. This system provides a uniform linear laser heat source with the surface scanning width from 15 to 50mm according to the scanning height To examine the wide laser beam, He-Ne laser is used. Also, Acryl is used to confirm the laser beam pattern by bum-pattern print To analyze the energy distribution of the wide laser ben empirical values and theoretical values are compared and discussed. To improve the efficiency of the wide laser beam optical system, methods are suggested by the optical theories. For larger area processing like turbine blade, drawing blade, cold roller and guide plate, optimal overlapping locations have been calculated and analyzed by geometric and optical theories.

  • PDF

Influence of the Entrance and Exit Lengths on the Natural Convection Heat Transfer of a Cylinder in a Duct (도관내 원형관의 자연대류 열전달에서 입구 및 출구 길이 효과)

  • Lim, Chul-Kyu;Chung, Bum-Jin
    • Journal of Energy Engineering
    • /
    • v.21 no.1
    • /
    • pp.18-25
    • /
    • 2012
  • This work investigated the influence of the chimney dimensions(exit and entrance length, and diameter) on the heat transfer of a vertical cylinder in a duct. The measured mass transfer rates for the natural convection of vertical cylinder in a duct were presented for Prandlt number 2,094, Rayleigh number in the range of $4.55{\times}10^9$, $5.79{\times}10^{10}$, and $1.69{\times}10^{11}$. Experiments were performed using a copper sulfate electroplating system to simulate heat transfer based upon the analogy concept. The diameter of the duct was varied from 0.06 m to 0.14 m, and the heights from 0.30 m to 1.10 m. Nusselt numbers measured at open channel condition agreed well with the existing laminar heat transfer correlations for vertical plate developed by Le Fevre. The increase of the exit length enhanced the heat transfer up to a certain duct height but further increase does not affects the heat transfer. The heat transfer decreased with increasing the entrance length up to a certain duct height and was constant at further increase. The Nusselt number decreased with increasing the diameter of duct, until Nusselt number becomes similar to that at open channel beyond a certain diameter.