• 대한기계학회논문집
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• 제18권7호
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• pp.1751-1758
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• 1994

A new set of governing equations is derived for the dynamic analysis of the Free-Piston Stirling Engines(EPSE). Equations from the ideal adiabatic model for the thermodynamic analysis of the working fluid are incoporated with the equations of motion for the moving masses of the system, resulting in a set of nonlinear differential equations. The coupled set of equations are numerically integrated with proper intial conditions to obtain a steady state response of the engine. The proposed method is compared with the conventional method of analyzing EPSE based mainly on the ideal isothermal model. The results clearly shows the limitationsl of the conventional methods and the relative advantages of the method proposed in the present study.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계학술대회논문집
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• pp.147-150
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• 2005

The torsion beam axle type is widely used in the rear suspension for small passenger car because of low cost, good performance and etc. The FE and dynamic analysis using the computer are very helpful for the efficiency of the torsion beam design. First of all, the reliability on the computational model must be verified for the analysis. In this study, The FE model of the torsion beam was verified according to comparison with he test data. And after making the flexible body using the FE model, the dynamic characteristic of the tubular type torsion beam axles was compared with that of the V-beam type.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.750_751
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• 2009

This paper deals with the PM performance evaluations in a pole changing memory motor (PCMM) using a coupled transient finite element method (FEM) and Preisach modeling, which is presented to analyze the magnetic characteristics of permanent magnets. The focus of this paper is the dynamic characteristics evaluation relative to magnetizing direction and the pole number of machine on redemagnetization condition in a pole changing memory motor

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 춘계학술대회논문집
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• pp.778-781
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• 2008

The aim of this paper is to analyze the dynamic responses of pantograph-overhead contact line coupled system by using a condition monitoring system. The monitoring items are strain, vertical displacement and acceleration of a contact wire. Both strain and vertical displacement in the contact wire depends on uplift force and train velocity. Measurement of acceleration shows that the passage of the pantograph gives an impact force to a hard point on a contact wire.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2010년도 춘계학술대회 논문집
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• pp.1478-1485
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• 2010

In this paper, the nonlinear dynamic response of Vehicle-Bridge interaction with the coupled equations of motion including nonlinear Hertzian contact is presented. The moving train model is chosen to have 10 degrees of freedom (DOF). The bridge is modeled as 2D Euler-Bernoulli beam element with 4 DOF for each element, two for rotations and another two for translations. The nonlinear Hertzian contact is used to simulate the interaction between vehicle and bridge. Base on the relationship of wheel displacement of the vehicle and the vertical displacement of the bridge in Hertzian contact, the coupled equations of motion of the whole system is derived. The convenient formulation was encoded into a computer program. The contact forces, contact area and stress of the rail surface were also computed. The accuracy and efficiency of the proposed program are verified and compared with exact analytical solution and other previous studies. Various numerical examples and parametric studies have demonstrated the versatility and applicability of the proposed program.

• Wind and Structures
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• 제21권3호
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• pp.311-329
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• 2015

A method for analyzing the coupled wind-vehicle-bridge system is proposed that also considers the shielding effect of the bridge tower with triangular wind barriers. The static wind load and the buffeting wind load for both the bridge and the vehicle are included. The shielding effects of the bridge tower and the triangular wind barriers are incorporated by taking the surface integral of the wind load. The inter-history iteration is adopted to solve the vehicle-bridge dynamic equations with time-varying external loads. The results show that after installing the triangular wind barriers in the area of the bridge tower, the bridge response and the vehicle safety factors change slightly. The peak value of the train car body acceleration is significantly reduced when the wind barrier size is increased.

• Coupled systems mechanics
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• 제1권1호
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• pp.39-57
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• 2012

This study intends to explore dynamic interaction behaviors between actively controlled maglev vehicle and guideway girders by considering the nonlinear forms of electromagnetic force and current exactly. For this, governing equations for the maglev vehicle with ten degrees of freedom are derived by considering the nonlinear equation of electromagnetic force, surface irregularity, and the deflection of the guideway girder. Next, equations of motion of the guideway girder, based on the mode superposition method, are obtained by applying the UTM-01 control algorithm for electromagnetic suspension to make the maglev vehicle system stable. Finally, the numerical studies under various conditions are carried out to investigate the dynamic characteristics of the maglev system based on consideration of the linear and nonlinear electromagnetic forces. From numerical simulation, it is observed that the dynamic responses between nonlinear and linear analysis make little difference in the stable region. But unstable responses in nonlinear analysis under poor conditions can sometimes be obtained because the nominal air-gap is too small to control the maglev vehicle stably. However, it is demonstrated that this unstable phenomenon can be removed by making the nominal air-gap related to electromagnetic force larger. Consequently it is judged that the nonlinear analysis method considering the nonlinear equations of electromagnetic force and current can provide more realistic solutions than the linear analysis.

• International Journal of Naval Architecture and Ocean Engineering
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• 제8권3호
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• pp.252-261
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• 2016

A spar-type floating substructure that is being widely used for offshore wind power generation is vulnerable to resonance in the heave direction because of its small water plane area. For this reason, the stable dynamic response of this floating structure should be ensured by accurately identifying the resonance characteristics. The purpose of this study is to analyze the characteristics of the combination resonance between the excitation frequency of a regular wave and natural frequencies of the floating substructure. First, the nonlinear equations of motion with two degrees of freedom are derived by assuming that the floating substructure is a rigid body, where the heaving motion and pitching motions are coupled. Moreover, to identify the characteristics of the combination resonance, the nonlinear term in the nonlinear equations is approximated up to the second order using the Taylor series expansion. Furthermore, the validity of the approximate model is confirmed through a comparison with the results of a numerical analysis which is made by applying the commercial software ANSYS AQWA to the full model. The result indicates that the combination resonance occurs at the frequencies of ${\omega}{\pm}{\omega}_5$ and $2{\omega}_{n5}$ between the excitation frequency (${\omega}$) of a regular wave and the natural frequency of the pitching motion (${\omega}_{n5}$) of the floating substructure.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 추계학술대회논문집
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• pp.401-406
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• 2008

This paper proposes a method to calculate the static characteristics of the FDBs with the curved surface. The general Reynolds equations are derived for the curved surfaces in the ${\theta}s$ plane. And the Reynolds equation is transformed to the finite element equations by considering the continuity of pressure and flow at the interface between the curved, journal and the thrust bearings. It also includes the Reynolds boundary condition in the numerical analysis to simulate the cavitation phenomenon. The static characteristics of the coupled journal and conical bearings were investigated due to the variation of conical angle. It shows that the conical angle is one of the important design parameters affecting the static and dynamic characteristics of FBBs.

• Structural Engineering and Mechanics
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• 제31권3호
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• pp.277-296
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• 2009

The paper investigates the dynamic behaviour of stiffened panels. The coupled differential equations for eccentric stiffening configuration are first derived. Then a semi-analytical procedure for dynamic analysis of stiffened panels is presented. Unlike finite element or finite strip methods, where the plate is discretized into a set of elements or strips, the plate in this procedure is treated as a single element. The potential energy of the structure is first expressed in terms generalized functions that describe the longitudinal and transverse displacement profiles. The resulting non-linear strain energy functions are then transformed into unconstrained optimization problem in which mathematical programming techniques are employed to determine the magnitude of the lowest natural frequency and the associated mode shape for pre-selected plate/stiffener geometric parameters. The described procedure is verified with other numerical methods for several stiffened panels. Results are then presented showing the variation of the natural frequency with plate/stiffener geometric parameters for various stiffening configurations.