• Title/Summary/Keyword: 구속조건 식

Search Result 20, Processing Time 0.108 seconds

A Study on Numerical Analysis of Wheel-rail Contact Points (차륜과 레일 접촉위치의 수치해석에 관한 연구)

  • Kang, Ju-Seok
    • Journal of the Korean Society for Railway
    • /
    • v.12 no.2
    • /
    • pp.236-242
    • /
    • 2009
  • This paper presents a numerical analysis method to determine flange contact at variable wheel positions. The shapes of the wheel and rail surface functions with surface parameters. The Newton-Rhapson method for wheel-rail contact can provide fast solutions, but may not yield true values at optimization process with the condition that minimum distance is zero can time-consuming. A compound method, combining the Newton-Rhapson methods the optimization process method is proposed to provide exact solutions efficiently.

A Study on the Dynamic Analysis of Railway Vehicle by Using Track Coordinate System (트랙좌표계를 이용한 철도차량의 동역학 해석에 관한 연구)

  • Kang, Juseok
    • Transactions of the Korean Society of Automotive Engineers
    • /
    • v.21 no.2
    • /
    • pp.122-130
    • /
    • 2013
  • Rail geometries such as cant, grade and curvature can be easily represented by means of a track coordinate system. In this analysis, in order to derive a dynamic and constraint equation of a wheelset, the track coordinate system is used as an intermediate stage. Dynamic and constraint equations of railway vehicle bodies except the wheelset are written in the Cartesian coordinate system as a conventional method. Therefore, whole dynamic equations of a railway vehicle are derived by combining wheelset dynamic equations and dynamic equations of railway vehicle bodies. Constraint equations and constraint Jacobians are newly derived for the track coordinate system. A process for numerical analysis is suggested for the derived dynamic and constraint equations of a railway vehicle. The proposed dynamic analysis of a railway vehicle is validated by comparison against results obtained from VI-RAIL analysis.

Use of Parametric Generalized Coordinates for Kinematic Constraint Formulation of Low Degree-of-Freedom Joints (저자유도 조인트의 구속조건 생성을 위한 파라메트릭 일반좌표 이용)

  • Lee, Jung Keun;Lee, Chul Ho;Bae, Dae Sung
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.37 no.10
    • /
    • pp.1261-1267
    • /
    • 2013
  • In multibody mechanical systems, low-degree-of-freedom (DOF) joints such as revolute and translational joints are much more frequently used than high-DOF joints. In order to formulate kinematic constraint equations, especially for low-DOF joints, in an efficient and systematic manner, this paper presents a parametric generalized coordinate formulation as a new approach for describing constraint equations. In the proposed approach, joint constraint equations are formulated in terms of a mixed set of Cartesian and parametric generalized coordinates, which drastically reduces the complexity and computational cost of the partial derivatives of the constraints such as the constraint Jacobian. The proposed formulation is validated using a simple cylinder-crank system with an implicit integrator.

Analysis of Dynamic Equilibrium Configuration of Speed Governor (조속기의 동적 평형위치 해석)

  • Kang, Juseok
    • Journal of the Korea Academia-Industrial cooperation Society
    • /
    • v.14 no.10
    • /
    • pp.4733-4738
    • /
    • 2013
  • This paper proposes a method to obtain the dynamic equilibrium configuration of a constrained mechanical system by using multibody dynamic analysis. Dynamic equilibrium equations with independent coordinates are derived from the time-dependent constraint equations and dynamic equations of a multibody system. The Newton-Raphson method is used to find numerical solutions for nonlinear algebraic equations that are composed of the dynamic equilibrium and constraint equations. The proposed method is applied to obtain the dynamic equilibrium configuration of a speed governor, and the results are verified on the basis of the results from conventional dynamic analysis. Furthermore, vertical displacements at equilibrium configuration, which varied with the rotational velocity of the speed governor, are calculated, and design parameter analysis of the equilibrium configuration is presented.

Approximate Synthesis of 5-SS Multi Link Suspension Systems for Steering Motion (조향 운동을 고려한 5-SS 멀티링크 현가장치의 근사 합성)

  • Kim, Seon-Pyeong;Sim, Jae-Gyeong;An, Byeong-Ui;Lee, Eon-Gu
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.25 no.1
    • /
    • pp.32-38
    • /
    • 2001
  • This paper presents an approximate synthesis of 5-SS multi link suspension for 2 D.O.F motions. In the proposed synthesis method, alteration curves of camber, toe, kingpin and caster angles are optimized during the bump rebound and the steering motions. And joint positions can be located within desired boundari es. Especially, steering motions are considered for control of kingpin offset and caster trail. Prescribed motions contain both wheel center positions and imaginary kingpin axes in the multi link type suspension. Constraint equations are formulated with di splacement matrix and velocity matrix using instantaneous screw axis.

A Gemetric Kinematic Analysis of Constrained Multibody System (구속된 다물체 시스템을 위한 기하학적 운동구속론)

  • 김재용;배대성;한창수;이상호
    • Transactions of the Korean Society of Automotive Engineers
    • /
    • v.2 no.4
    • /
    • pp.80-90
    • /
    • 1994
  • Basic constraint equations derived from orthogonality conditions between a pair of body-fixed vectors and a body-fixed vector or a vector between two bodies are reformulated by using relative coordinate kinematics between two adjacent reference frames. Arithmetic numbers of operations required to compute derivatives of the constraint equations are drastically reduced. A mixed formulation of relative and cartesian coordinates is developed to further simplify derivatives of the constraints. Advantages and disadvantages of the new formulation are discussed. Possible singularity problem of para llelism constraints is resolved by introducing an extra generalized coordinate. Kinematic analysis of a McPherson strut suspension system are carried out to illustrate use and efficiency of the new formulation.

  • PDF

Vibration Analysis of a Moving Mass Travelling on the Timoshenko Rotating Shaft (티모센코 회전축을 따라 움직이는 질량의 진동해석)

  • Park, Yong-Suk
    • Journal of the Korea Academia-Industrial cooperation Society
    • /
    • v.9 no.4
    • /
    • pp.859-864
    • /
    • 2008
  • The dynamic interaction between the moving mass and the rotating Timoshenko shaft is investigated. The moving speed of the mass is presented by a constraint equation related to the rotating speed of the shaft. The dimensionless equations of motion for the rotating shaft with a moving mass by using the Timoshenko's beam theory. The dynamic responses of this system are studied. influences of dimensionless parameters such as the rotating speed ratio. the Rayleigh coefficient and the dimensionless axial force are discussed on the transient response and the maximum deflection of the moving system.

Kinematic Synthesis and Analysis of RSS-SC Suspension System Using Acceptable Tolerances of Motion (운동의 허용공차를 이용한 RSSS-SC 현장장치의 기구학적 설계)

  • 김선평;심재경
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.24 no.11
    • /
    • pp.2672-2679
    • /
    • 2000
  • In synthesizing and RSSS-SC mechanism that is the kinematic model of the McPherson strut suspension system in automobiles, the design equations for R-S, S-S and S-C dyads should be solved separately for a given set of prescribed positions. The number of prescribed positions that the RSSS-SC mechanism can be synthesized is up to three because of the S-C dyad. This limitation may cause unsatisfactory results in synthesized joint positions. This paper presents a kinematic synthesis method to place the joints of an RSSS-SC mechanism in desired boundaries by varying the prescribed positions of the mechanism within acceptable tolerances. The sensitivity analysis of the joint positions is used determine which displacement parameter should be altered to fulfill this task.

Approximate Synthesis of 5-SS Multi Link Suspension System (근사 합성법을 이용한 5-SS 멀티 링크 현가장치의 기구학적 설계)

  • 김선평;심재경;안병의;이언구
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.24 no.11
    • /
    • pp.2665-2671
    • /
    • 2000
  • Dimensional Synthesis, which is apart of kinematic synthesis, is to determine the dimensions of a mechanism of preconceived typer for a specified task and prescribed performance. In this paper, in an effort to provide designers with flexibility, a dimensional approximate synthesis method is presented for utilizing prescribed tolerance both the displacement and joint positions of a mechanism to be synthesized. For this, a constrained optimization problem is formulated with displacement parameters and joint positions as variables. The proposed method is applied to the synthesis of a 5-SS multi link suspension mechanism. The method discussed here, however, can be easily applied to any mechanism of which the kinematic constraint equations can be derived.

Calculation of Critical Speed of Railway Vehicle by Multibody Dynamics Analysis (다물체 동역학 해석방법을 이용한 철도차량의 임계속도 계산)

  • Kang, Juseok
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.37 no.11
    • /
    • pp.1371-1377
    • /
    • 2013
  • In this analysis, a method is presented to calculate the critical speed of a railway vehicle by using a multibody dynamic model. The contact conditions and contact forces between the wheel and the rail are formularized for the wheelset model. This is combined with the bogie model to obtain a multibody dynamic model of a railway vehicle with constraint conditions. First-order linear dynamic equations with independent coordinates are derived from the constraint equations and dynamic equations of railway vehicles using the QR decomposition method. Critical speeds are calculated for the wheelset and bogie dynamic models through an eigenvalue analysis. The influences of the design parameters on the critical speed are presented.