• Title/Summary/Keyword: rotational inertia

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A Design on the chassis frame of passenger car using beam and spring Elements (빔과 스프링 요소를 이용한 승용차의 차체 프레임 설계)

  • 이동찬;이상호;한창수
    • Transactions of the Korean Society of Automotive Engineers
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    • v.7 no.9
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    • pp.89-96
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    • 1999
  • This paper presents the optimization design technique on the joint stiffness and section characteristic factors of chassis frame, by using beam and spring elements in a given design package. Two correction methods are used for the optimization design of chassis frame. First is the equivalent inertia of moment method in relation to the section characteristic factors of joint zones, which are thickness , width and height of frame channel section. Second is the rotational spring element with joint stiffness of joint zones. The CAE example shows that the relationship of section characteristic factors and joint stiffness can effectively be used in designing chassis frame. In this point, if static and dynamic targets are given, the joint-zone and section characteristic factors of chassis frame intended may be designed and defined by using beam and rotational spring elements.

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Free Vibrations of Tapered Beams with General Boundary Conditions and Tip Masses (끝단 질량과 일반적인 단부조건을 갖는 변단면 보의 자유진동)

  • 오상진;이병구;박광규;이종국
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2003.11a
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    • pp.802-807
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    • 2003
  • The purpose of this paper is to investigate the free vibration characteristics of tapered beams with translational and rotational springs and tip masses at the ends. The beam model is based on the classical Bernoulli-Euler beam theory. The governing differential equation for the free vibrations of linearly tapered beams is solved numerically using the corresponding boundary conditions. Numerical results are compared with existing solutions by other methods for cases in which they are available. The lowest three natural frequencies are calculated over a wide range of non-dimensional system parameters: the translational spring parameter, the rotational spring parameter, the mass ratio and the dimensionless mass moment of inertia.

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Study of of Flexible Multibody Dynamics with Rotary Inertia (회전관성 효과를 고려한 탄성 다물체 동력학에 관한 연구)

  • 김성수
    • Journal of KSNVE
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    • v.6 no.3
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    • pp.287-296
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    • 1996
  • A virtual work form of flexible multibody dynamic formulation with rotary inertia has been derived. For the analysis of large flexible multibody systems, deformation modal coordinates have been employed to represent coupled motion between gross and vibrational motion. For the efficient evaluation of the entries in the mass matrix, a flexible body has been treated as a collection of mass points. The rotary inertia was generated from the consistent mass matrix in a finite element model. Deformation mode shapes were obtained from finite element analysis. Bending and twisting vibration analyses of a cantilever have been carried out to see rotary inertia effects. A space flexible robot simulation has been also carried out to show effectiveness of the proposed formulation. This formulation is effective to the model that consists of beam, plate, or shell element that contains rotational degree of freedom at the nodal point. It is also effective to the flexible body model to which a large lumped rotary inertia is attached.

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Moment of inertia of liquid in a tank

  • Lee, Gyeong Joong
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.6 no.1
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    • pp.132-150
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    • 2014
  • In this study, the inertial properties of fully filled liquid in a tank were studied based on the potential theory. The analytic solution was obtained for the rectangular tank, and the numerical solutions using Green's 2nd identity were obtained for other shapes. The inertia of liquid behaves like solid in recti-linear acceleration. But under rotational acceleration, the moment of inertia of liquid becomes small compared to that of solid. The shapes of tank investigated in this study were ellipse, rectangle, hexagon, and octagon with various aspect ratios. The numerical solutions were compared with analytic solution, and an ad hoc semi-analytical approximate formula is proposed herein and this formula gives very good predictions for the moment of inertia of the liquid in a tank of several different geometrical shapes. The results of this study will be useful in analyzing of the motion of LNG/LPG tanker, liquid cargo ship, and damaged ship.

The Study on the Added Moment of Inertia of Two Dimensional Cylinder induced by the Torsional Vibration coupled with the Flexural Vibration (자유수면(自由水面)에서의 비틀림 수평(水平)굽힘의 연성진동(連成振動)을 하는 선체단면형(船體斷面形)의 이차원적(二次元的) 부가관성(附加慣性) Moment에 관(關)한 연구(硏究))

  • S.S.,Kim
    • Bulletin of the Society of Naval Architects of Korea
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    • v.7 no.2
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    • pp.3-18
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    • 1970
  • An investigation was made for the added mass moment of inertia induced by the rotational motion of the cylinder with hull section on water in order to obtain the information to estimate the natural frequency of the torsional vibration of ships. The special consideration to the effect of the draught upon the added mass moment of inertia is taken into account in the study. In this paper, the general expression for the added mass coefficients of moment of inertia of arbitary two dimensional forms induced by the torsional vibration, was derived by the author. Hence, the coefficients for these forms are represented as functions of parameters, the section area coefficient and draft beam ratio, from which the added mass coefficients for arbitrary forms can be obtained. The result was shown in a chart for estimation of the added mass moment of inertia induced by the torsional vibration, as first trial, for the convenience of practical use.

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Free Vibrations of Non-Circular Arches with Elastic Supports (탄성지점을 갖는 변화곡률 아치의 자유진동)

  • Oh, Sang-Jin;Kim, Gwon-Sik;Park, Kwang-Kyou
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2007.11a
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    • pp.340-343
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    • 2007
  • The differential equations governing free, in-plane vibrations of non-circular arches with the translational (radial and tangential directions) and rotational springs at the ends, including the effects of rotatory inertia, shear deformation and axial deformation, are solved numerically using the corresponding boundary conditions. The lowest four natural frequencies for the parabolic geometry are calculated over a range of non-dimensional system parameters: the arch rise to span length ratio, the slenderness ratio, and the translational and rotational spring parameters.

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Optimal Design of a High Speed Carbon Composite Air Spindle (고속 공기 주축부를 위한 복합재료 주축의 최적 설계)

  • Bang, Gyeong-Geun;Lee, Dae-Gil
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.25 no.11
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    • pp.1767-1776
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    • 2001
  • For the stable operation of high speed air spindle, the low rotational inertia and high damping ratio of spindle shafts as well as high fundamental natural frequency are indispensable. Conventional steel spindles are net appropriate for very high speed operation because of their high rotational inertia and low damping ratio. In this study, a high speed spindle composed of carbon fiber epoxy composite shaft and steel flange was designed for maximum critical speed considering minimum static deflection and radial expansion due to bending load and centrifugal force during high speed relation. The stacking angle and the stacking thickness of the composite shaft and the adhesive bonding length of the 7teel flange were selected through vibrational analysis considering static and thermal loads due to temperature rise.

A Study on the Vibration Characteristics of Multi-span Beams (멀티스팬 빔의 진동특성에 관한 연구)

  • 홍진선
    • Journal of KSNVE
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    • v.8 no.5
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    • pp.856-861
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    • 1998
  • Several reactor system components, such as heat exchange tubes, fuel fins, controlrods, and various instruments are beam-like components. This study presents a simple solution method for calculating the natural frequencies and modes of beams supported by linear and torsional springs and attached concentrated mass and rotational inertia at some intermediate points. For a general multi-span beam, theoretical method is proposed to analyze the exact solution about vibrational characteristics with respect to the nondimensional parameters. And the results obtained using the numerical models are presented and discussed.

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Vibration Characteristics of Immersed Column with Soft Base (연약지점을 갖는 유체에 잠긴 기둥의 진동 특성)

  • Oh Sang-Jin;Mo Jeong-Man
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2006.04a
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    • pp.697-702
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    • 2006
  • This paper deals with the free vibrations of immersed columns with soft base. The support condition of the column is represented by using a translational spring and a rotational spring. The eccentricity and rotatory inertia of the concentrated mass at the top are taken into account. In the governing equation for the free vibration of column, the density of immersed part was modified to account for the added fluid mass. The governing differential equations are solved numerically using the corresponding boundary conditions. Numerical results are presented to show the effects on the natural frequencies of non-dimensional system parameters: the mass density ratio of fluid to column, the ratio of fluid depth to span length, the ratio of tip mass to total column mass, the dimensionless mass moment of inertia, the eccentricity, the translation spring parameter, and the rotational spring parameter.

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Sensorless IPMSM Control Based on an Extended Nonlinear Observer with Rotational Inertia Adjustment and Equivalent Flux Error Compensation

  • Mao, Yongle;Yang, Jiaqiang;Yin, Dejun;Chen, Yangsheng
    • Journal of Power Electronics
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    • v.16 no.6
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    • pp.2150-2161
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    • 2016
  • Mechanical and electrical parameter uncertainties cause dynamic and static estimation errors of the rotor speed and position, resulting in performance deterioration of sensorless control systems. This paper applies an extended nonlinear observer to interior permanent magnet synchronous motors (IPMSM) for the simultaneous estimation of the rotor speed and position. Two compensation methods are proposed to improve the observer performance against parameter uncertainties: an on-line rotational inertia adjustment approach that employs the gradient descent algorithm to suppress dynamic estimation errors, and an equivalent flux error compensation approach to eliminate static estimation errors caused by inaccurate electrical parameters. The effectiveness of the proposed control strategy is demonstrated by experimental tests.