• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.1
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• pp.99-106
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• 2011

In this study, the dynamic contact of a catenary system is analyzed by using the finite element method. We derive the equations of motion for the catenary system by taking into consideration tension on the catenaries. After establishing the weak form, they are spatially discretized with beam elements. Then, we analytically calculated the wave propagation speed for a string, bar, beam, and the catenaries subjected to tension. Further, finite element computer program for contact dynamic analyses is developed. Finally, we analyze the wave propagation response corresponding to the moving load to the contact line are calculated.

• Journal of KSNVE
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• v.8 no.2
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• pp.239-250
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• 1998

Traditionally, intake noise from internal combustion engine has not recevied much attention compared to exhaust noise. But nowadays, intake noise is a major contributing factor to automotive passenger compartment noise levels. The main objective of this paper is to identify the mechanism of generation, propagation and radiation of the intake noise. With a simplest geometric model, one of the main noise sources for the intake stroke is found to be the pressure surge, which is generated after intake valve closing. The pressure surge, which has the nonlinear acoustic behavior, propagates and radiates with relatively large amplitude. In this paper, unsteady compressible Navier-Stokes equations are employed for the intake stroke of axisymmetric model having a single moving cylinder and a single moving intake valve. To simulate the periodic motion of the piston and the valve, unsteady deforming mesh algorithm is employed and Thompson's non-reflecting boundary condition is applied to the radiation field. In order to resolve the small amplitude waves at the radiation field, essentially non-oscillatory(ENO) schemes with an artificial compression method (ACM) are used.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.2575-2580
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• 2005

In this paper, we address two position control scheme; the lead-lag control and the sliding mode control for a stage system, which is levitated and driven by electric magnetic actuators. This consists of a levitating object (called platen) with 4 permanent magnetic linear synchronous motors in parallel. Each motor generates vertical force for suspension against gravity and propulsion force horizontally as well. This stage can generate six degrees of freedom motion by the vertical and horizontal forces. Dynamic equations of the stage system are derived simply. The sliding mode control algorithm is more effective than the lead-lag control algorithm to reduce effects from movements and disturbances of other axis.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.04a
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• pp.701-706
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• 2012

This research is concerned with the derivation of equations of motion for a slewing beam and the application of input shaper to the bang-bang control to achieve vibration suppression. When a uniform beam with a tip mass rotates about the axis perpendicular to the undeformed beam's longitudinal axis, it experiences inertial loading. Hence, the beam vibrates. In this paper, we used the input shaper for the maneuvering control to suppress vibrations. The maneuvering control which can achieve a minimum-time control is a bang-bang control. The input-shaped bang-bang maneuvering is used to suppress vibrations both theoretically and experimentally. The slewing beam experiment is not an easy subject because of the inherent damping existing inside the rotor. We propose the use of a negative damping to eliminate the rotor damping. Numerical and experimental results show that the input-shaper can be effectively used for the vibration suppression of a slewing beam.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.4 no.3
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• pp.53-61
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• 1984

A nonlinear formulation of a beam finite element(NB6) on the total Lagrangian mode for the geometrically nonlinear analysis of two-dimensional elastic framed structures is presented. The NB6 beam element has been degenerated from the three-dimensional continuum by introducing the deep beam assumptions and consists of three reference nodes and three relative nodes. The element characteristics are derived by discretizing the beam equations of motion using the Galerkin weighted residual method and are reduced-integrated repeatedly for each loading step by the Newton-Raphson iteration techpique. Several numerical examples are given to demonstrate the accuracy and versatility of the proposed nonlinear NB6 beam element.

• International Journal of Precision Engineering and Manufacturing
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• v.5 no.4
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• pp.50-60
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• 2004

A very flexible beam can be used to model various types of continuous mechanical parts such as cables and wires. In this paper, the dynamic properties of a very flexible beam, included in a multibody system, are analyzed using absolute nodal coordinates formulation, which is based on finite element procedures, and the general continuum mechanics theory to represent the elastic forces. In order to consider the dynamic interaction between a continuous large deformable beam and a rigid multibody system, a combined system equations of motion is derived by adopting absolute nodal coordinates and rigid body coordinates. Using the derived system equation, a computation method for the dynamic stress during flexible multibody simulation is presented based on Euler-Bernoulli beam theory, and its reliability is verified by a commercial program NASTRAN. This method is significant in that the structural and multibody dynamics models can be unified into one numerical system. In addition, to analyze a multibody system including a very flexible beam, formulations for the sliding joint between a very deformable beam and a rigid body are derived using a non-generalized coordinate, which has no inertia or forces associated with it. In particular, a very flexible catenary cable on which a multibody system moves along its length is presented as a numerical example.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.2
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• pp.167-175
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• 2011

The purpose of this study is to examine the impact that change in speed and modeling methods has on maglevs' runnability. The study constructed equations of motion on 4-DOF, 6DOF, and 10-DOF vehicles respectively and carried out numerical analysis, applying 4th Runge Kutta method, in order to run six different model maglev as changing the vehicles speed on the same bridge that had 2000 to 1 deflection. The analysis revealed that maglev's runnability improved as speed was lower and the specific model had higher number of bogey and EMS.

• The KSFM Journal of Fluid Machinery
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• v.18 no.6
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• pp.5-11
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• 2015

In a pressurized water reactor (PWR), control rod assembly (CRA) falls into the guide tubes of a fuel assembly due to gravity for scram. Various theoretical approaches and numerical analyses have been performed because its shape is simple and its design was completely developed several decades ago. A control rod assembly for a sodium-cooled faster reactor (SFR) which is geometrically more complicated is being actively developed in Korea nowadays. Drop time and impact velocity of a CRA are important parameters with respect to reactivity insertion time and the mechanical robustness of a CRA and a guide duct. In this paper, computational method considering simultaneously the equation of motion for rigid body and the Navier-Stokes equations for fluid is suggested and verified by comparison with theoretical analysis results. Through this valuable CFD analysis method, drop time and impact velocity of initially designed SFR CRA are evaluated before performing scram tests with it.

• Journal of the Society of Naval Architects of Korea
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• v.35 no.1
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• pp.46-53
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• 1998

In this paper, we studied to improve Inoue's[1] and Kijima's[2] model used to predict ship's manoeuvrability at initial design state. To perform this work, we carried out PMM(Planar motion Mechanism) test and rudder open water test for 12 models of low-speed blunt-ship which have horn type rudders and bulbs in afterbody. As we adopted MMG(Mathematical Modelling Group) model, we could analyze hydrodynamic and MMG experimental coefficients. The regression analyses by principle parameters were carried out for hydrodynamic and MMG experimental coefficients. The regression analyses by principle parameters were carried out for hydrodynamic and MMG experimental coefficients and the equations by regression analysis wee used to search sensitivities and to estimate ship's manoeuvrability. We had simulated ship's manoeuvrability to check revised MMG.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.5
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• pp.793-800
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• 2006

DQM(differential quadrature method) is applied to computation of eigenvalues of the equations of motion governing the free in-plane vibration fur circular curved beams including both rotatory inertia and shear deformation. Fundamental frequencies are calculated for the members with clamped-clamped end conditions and various opening angles. The results are compared with numerical solutions by other methods for cases in which they are available. The differential quadrature method gives good accuracy even when only a limited number of grid points is used.