• Title/Summary/Keyword: Circular shaft

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Effects of exhaust pipe curvature on the performance of a 4 cycle diesel engine (디이젤 엔진에서 排氣管 屈曲이 엔진性能에 미치는 影響)

  • 문병수;서정윤
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.10 no.5
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    • pp.735-741
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    • 1986
  • An experimental study on the effects of exhaust pipe curvature on the performance of a diesel engine is presented. The experiments were carried out on a 4-cycle, 216 c.c diesel engine and two types of pipe curvature, circular arc and rectangle, were tested. The shaft output, shaft torque and specific fuel consumption were obtained by inserting bent pipes of different dimensions into the exhaust pipe at various engine operation conditions. It was found that the engine performance was decreased by the circular arc bent pipe and the effects were dominated by its arc angle. The decrease of engine performance was minimized by the arc angle of 180.deg.. By the rectangle pipes the performance was more decreased and the effects were little influenced by its dimensions.

Effect of the rotation on a non-homogeneous infinite cylinder of orthotropic material with external magnetic field

  • Hussein, Nahed S.;Bayones, F.S.;Mahmoud, S.R.
    • Structural Engineering and Mechanics
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    • v.54 no.1
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    • pp.135-148
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    • 2015
  • The present investigation is concerned with a study effect of magnetic field and non-homogenous on the elastic stresses in rotating orthotropic infinite circular cylinder. A certain boundary conditions closed form stress fields solutions are obtained for rotating orthotropic cylinder under initial magnetic field with constant thickness for three cases: (1) Solid cylinder, (2) Cylinder with a circular hole at the center, (3) Cylinder mounted on a circular rigid shaft. Analytical expressions for the components of the displacement and stress fields in different cases are obtained. The effect of rotation and magnetic field and non-homogeneity on the displacement and stress fields are studied. Numerical results are illustrated graphically for each case. The effects of rotating and magnetic field and non-homogeneity are discussed.

Stress and Vibration Analysis with respect to the change of the Shape of Screw Blade and the Hole for Centrifuge (원심분리기용 스크류의 블레이드 및 원공형상변화에 따른 응력 및 진동해석)

  • 한근조;이성욱;심재준;한동섭;안찬우;서용권;김태형
    • Journal of the Korean Society for Precision Engineering
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    • v.20 no.9
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    • pp.118-125
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    • 2003
  • In this study, we carried out the finite element analysis for the screw of centrifuge that is the weakest part of the centrifuge for sewage management. Centrifugal force caused by rotation with velocity of 4000rpm was applied at the screw. Structural analysis was done with respect to the change of the ratio of blade pitch($R_P$), shaft diameter($R_D$) and extended hole($R_E$). When the area of circular hole is equal to that of extended holes, maximum equivalent stresses in the screw with circular and extended circular hole were compared. And then natural frequency analysis was executed for the same model. Three mode shapes were used to explain the vibration characteristics of each screw. Convergence study was accomplished fur more accurate results.

Earth pressures acting on vertical circular shafts considering arching effects in c-${\phi}$ soils: I. Theory (c-${\phi}$ 지반에서의 아칭현상을 고려한 원형수직터널 토압: I. 이론)

  • Kim, Do-Hoon;Lee, Dea-Su;Kim, Kyung-Ryeol;Lee, Yong-Hee;Lee, In-Mo
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.11 no.2
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    • pp.117-129
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    • 2009
  • Several researches have been done to estimate the earth pressure on a vertical circular shaft considering three dimensional arching effect and verified them by conducting model tests. However, any equation suggested so far is not applicable in case of multi-layered soils and/or C-${\phi}$ soils. In this study, new equation for estimating the earth pressure acting on the vertical shaft in c-${\phi}$ soils is proposed. A parametric study is performed to investigate the significance of the cohesion when estimating the coefficient of earth pressure in C-${\phi}$ soils and estimating earth pressures in vertical shafts. A method which can estimate the earth pressure on vertical shafts in layered soils is also proposed by assuming a failure surface in layered soils and using the modified equation. This paper is Part I of companion papers focusing on the theoretical aspect of model developments; the experimental verification will be made in Part II.

Development of design charts for concrete lining in a circular shaft (원형수직구 콘크리트라이닝 단면설계도표 개발)

  • Shin, Young-Wan;Kim, Sung-Soo;Kim, Young-Jin
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.12 no.2
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    • pp.165-175
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    • 2010
  • Recently, requirement of a long subsea tunnel has increased due to political, economical and social demands such as saving of distribution costs, improvement of traffic convenience, and regional development. Road and railroad tunnel need a shaft for construction and ventilation because of increase of tunnel length. Shaft diameter, lining sectional thickness and rebar quantity have to be determined for design of concrete lining in the shaft. A lot of structural analyses are needed for optimal design of concrete lining considering shaft diameter, load conditions and ground conditions. Design charts are proposed by structural analyses for various conditions in this study. A sectional thickness and rebar quantity can be easily determined using the proposed design charts.

A rational estimating method of the earth pressure on a shaft wall considering the shape ratio (벽체형상비의 영향을 합리적으로 고려한 원형수직구 벽체에 작용하는 토압산정방법)

  • Shin, Young-Wan;SaGong, Myung
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.9 no.2
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    • pp.143-155
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    • 2007
  • The earth pressure acting on a circular shaft wall is smaller than that acting on the wall in plane strain condition due to the three dimensional axi-symmetric arching effect. Accurate estimation of the earth pressure is required for the design of the shaft wall. In this study, the stress model considering the decrease of earth pressure due to the horizontal and vertical arching effect and the influence of shape ratio (shaft height/radius) is proposed. In addition, model test on the sandy soil is conducted and a comparison is made between the stress model and the test results. The comparison shows that the proposed stress model is in agreement with test results; decrease of shape ratio (increase of radius) leads to stress state equal to the plane strain condition and approximate stress distribution is found between stress model and model test results.

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Vibration and Stability Control of Rotating Composite Shafts via Collocated Piezoelectic Sensing and Actuation (압전감지기 및 압전작동기를 이용한 복합재료 회전축의 진동 및 안전성 제어)

  • Jeong, Nam-Heui;Kang, Ho-Shik;Yoon, Il-Sung;Song, Oh-Seop
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.31 no.2 s.257
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    • pp.152-159
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    • 2007
  • A study on the control of free vibration and stability characteristics of rotating hollow circular shafts subjected to compressive axial forces is presented in this paper. Both passive structural tailoring technique and active control scheme via collocated piezoelectric sensing and actuation are used in the study Gyroscopic and centrifugal forces combined with the compressive axial force contribute to the occurrence of divergence and flutter instabilities of the rotating shaft. The dual methodology based on the passive and active control schemes shows a high degree of efficiency toward postponement of these instabilities and expansion of the domain of stability of the system. The structural model of the shaft is based on an advanced thin-walled beam structure that includes the non-classical effects of transverse shear, anisotropy of constituent materials and rotatory inertia.

Vibration and Stability of Composite Thin-Walled Spinning Shaft (복합재료 회전축의 진동 특성 및 안정성 해석)

  • Yoon, Hyung-Won;Na, Sung-Soo
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2004.11a
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    • pp.1083-1088
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    • 2004
  • This paper deals with the vibration and stability of a circular cylindrical shaft, modeled as a tapered thin-walled composite beam and spinning with constant angular speed about its longitudinal axis, and subjected to an axial compressive force. Hamilton's principle and the assumed mode method are employed to derive the governing equations of motion. The resulting eigenvalue problem is analyzed, and the stability boundaries are presented for selected taper ratios and axial compressive force combinations. Taking into account the directionality property of fiber reinforced composite materials, it is shown that for a shaft featuring flapwise-chordwise-bending coupling, a dramatic enhancement of both the vibration and stability behavior can be reached. It is found that by the structural tailoring and tapering, bending natural frequencies, stiffness and stability region can be significantly increased over those of uniform shafts made of the same material. In addition, the particular case of a classical beam with internal damping effect is also included.

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Comparison of measured values and numerical analysis values for estimating smart tunnel based groundwater levels around vertical shaft excavation (수직구 굴착시 스마트 터널기반 지하수위 현장계측과 수치해석 비교 연구)

  • Donghyuk Lee;Sangho Jung
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.26 no.2
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    • pp.153-167
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    • 2024
  • Recently the ground settlement has been increasing in urban area according to development. And, this may attribute a groundwater level drawdown. This study presents an analysis of groundwater level drawdown for circular vertical shaft excavation of 「◯◯◯◯ double track railway build transfer operate project」. And, in-situ monitoring data and numerical analysis were compared. So, if we examine the groundwater level drawdown in design, ground conditions should be applied so that the site situation can be reflected. And, groundwater level should be considered a seasonal measurement in order to apply the appropriate groundwater level. It was confirmed a similar predicted value to groundwater level drawdown of in-situ monitoring data.

The Structural Characteristics of the Temporary Cofferdam in Accordance with the Shape and Size Obtained from Numerical Analysis (유한요소 해석을 통한 형상 및 크기에 따른 가물막이 특성 검토)

  • Kim, Hyun-Joo;Choi, Jin-O;Gwon, Yun-Ho
    • Journal of the Korean Geotechnical Society
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    • v.36 no.1
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    • pp.29-38
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    • 2020
  • These days the circular cross section cofferdam has been frequently used for the earth retaining structures or cut off wall such as ventilating opening, intake tower in cofferdam, shaft for emergency. By the arching effect, the circular cross section type cofferdam has more advantage than a polygon cofferdam in terms of the structural forces and moment. This paper shows the proper approach to analyze the circular cross section cofferdam using 2D Finite Element Method (FEM) for the circular stiffener (ring beam) evaluation. Besides, the various shapes of cofferdam indluding circular cross section have modeled the 3D Finite Element Mothod (FEM). The circular cross section cofferdam shows the minimum reaction force compared with the other shapes of cofferdam.