• 한국소음진동공학회논문집
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• 제20권10호
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• pp.907-914
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• 2010

While rubber components are extensively used in automobile vehicle, there are still a lot of difficulties in designing the rubber components applied in complex shapes and preloaded states because of the complicated material properties. In this paper, an efficient experimental method is suggested, which estimates the dynamic stiffness of a rubber component using rubber material test and static stiffness of the bush. And it is verified by comparing with FEM predictions and experimental results. This method is capable of predicting the dynamic stiffness of a rubber bush under various load conditions from minimized test data. Also it estimates dynamic characteristics of a rubber component using rubber material test and FEM calculation.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.1666-1671
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• 2003

Exact dynamic stiffness model for a uniform straight pipeline conveying unsteady fluid is formulated from a set of fully coupled pipe-dynamic equations of motion, in which the fluid pressure and velocity of internal flow as well as the transverse and axial displacements of the pipeline are all treated as dependent variables. The accuracy of the dynamic stiffness model formulated herein is first verified by comparing its solutions with those obtained by the conventional finite element model. The spectral element analysis based on the present dynamic stiffness model is then conducted to investigate the effects of fluid parameters on the dynamics and stability of an example pipeline problem.

• Structural Engineering and Mechanics
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• 제37권5호
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• pp.475-487
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• 2011

In a flexible multi-body dynamic system the typical topological optimization method for structures cannot be directly applied, as the stiffness varies with position. In this paper, the topological optimization of the flexible multi-body dynamic system is converted into structural optimization using the equivalent static load method. First, the actual boundary conditions of the control system and the approximate stiffness curve of the mechanism are obtained from a flexible multi-body dynamical simulation. Second, the finite element models are built using the absolute nodal coordination for different positions according to the stiffness curve. For efficiency, the static reanalysis method is utilized to solve these finite element equilibrium equations. Specifically, the finite element equilibrium equations of key points in the stiffness curve are fully solved as the initial solution, and the following equilibrium equations are solved using a reanalysis method with an error controlled epsilon algorithm. In order to identify the efficiency of the elements, a non-dimensional measurement is introduced. Finally, an improved evolutional structural optimization (ESO) method is used to solve the optimization problem. The presented method is applied to the optimal design of a die bonder. The numerical results show that the presented method is practical and efficient when optimizing the design of the mechanism.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2008년도 정기 학술대회
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• pp.72-77
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• 2008

Stability is a very important part which we must consider in structural design. In this paper, we take advantage of finite element method, and study about parametrical instability of star-dome structures, which is subjected to harmonically pulsating load. When calculating stiffness matrix, we consider elastic stiffness and geometrical stiffness simultaneously. In equation of motion, we represent displacements and accelerations by trigonometric series expansions, and then obtain Hill's infinite determinants. After first order approximation, we can get first and second order dynamic instability region finally.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.760-763
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• 2003

This study proposed the analysis of damage defection due to the change of the stiffness of structure by using the original and modified dynamic characteristics. The method is applied to examples of a cantilever and 3 degree of freedom by modifying the stiffness. The predicted damage detections are in good agreement with these from the structural reanalysis using the modified stiffness.

• 한국정밀공학회지
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• 제28권4호
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• pp.422-426
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• 2011

The spindle system is very important unit for the product accuracy in machine tools. A spindle system is designed by using the angular contact ceramic ball bearings, built-in motor, oil-air lubrication method and oil jacket cooling method. The static and dynamic analysis and stiffness evaluation of 45,000rpm spindle for machine tool has been investigated. Using a finite element method, we obtained some analyzed a static and dynamic characteristics of a spindle, such as natural frequency, harmonic analysis and we got the value of compliance through it. We evaluated stiffness by taking the inverse this value. A 45,000rpm spindle is successfully developed using the results.

• 소음진동
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• 제8권5호
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• pp.949-956
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• 1998

Complex and large lattice type structures are frequently used in design of bridge, tower, crane and aerospace structures. In general, in order to analyze these structures we have used the finite element method(FEM). This method is the most widely used and powerful method for structural analysis lately. However, it is necessary to use a large amount of computer memory and computational time because the FEM requires many degrees of freedom for solving dynamic problems exactly for these complex and large structures. For analyzing these structures on a personal computer, the authors developed the transfer stiffness coefficient method(TSCM). This method is based on the concept of the transfer of the nodal dynamic stiffness coefficient matrix which is related to force and displacement vector at each node. And we suggested TSCM for free vibration analysis of complex and large lattice type structures in the previous report. In this paper, we formulate forced vibration analysis algorithm for complex and large lattice type structures using extened TSCM. And we confirmed the validity of TSCM through computational results by the FEM and TSCM, and experimental results for lattice type structures with harmonic excitation.

• Steel and Composite Structures
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• 제16권6호
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• pp.577-593
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• 2014

An exact dynamic stiffness method is introduced for investigating the free vibration characteristics of the steel-concrete composite beams consisting of a reinforced concrete slab and a steel beam which are connected by using the stud connectors. The elementary beam theory is used to define the dynamic behaviors of the two beams and the relative transverse deformation of the connectors is included in the formulation. The dynamic stiffness matrix is formulated from the exact analytical solutions of the governing differential equations of the composite beams in undamped free vibration. The application of the derived dynamic stiffness matrix is illustrated to predict the natural frequencies and mode shapes of the steel-concrete composite beams with seven boundary conditions. The present results are compared to the available solutions in the literature whenever possible.

• Structural Engineering and Mechanics
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• 제7권1호
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• pp.81-94
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• 1999

The dynamic analysis of trusses using the finite element method tends to overlook the effect of local member dynamic behavior on the overall response of the complete structure. This is due to the fact that the lateral inertias of the members are omitted from the global inertia terms in the structure mass matrix. In this paper a condensed dynamic stiffness matrix is formulated and used to calculate the exact dynamic properties of trusses without the need to increase the model size. In the examples the limitations of current solutions are presented together with the exact results obtained from the proposed method.

• 소음진동
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• 제9권1호
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• pp.42-48
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• 1999

In this paper, a computer simulation method for dynamic analysis of the hydraulic engine mount system is proposed. The hydraulic engine mount system controls the damping characteristics using the viscosity of fluid flow The complex stiffness of the main rubber of the hydraulic engine mount system is computed by finite element analysis for the viscoelastic materials and hydro-static elements. A numerical analysis method is presented to solve nonlinear equations of the hydraulic engine mount system. which is composed of an engine mass, fluid in inertia track and a vertical inertia force of reciprocating mass in the engine. Also. dynamic properties of the hydraulic engine mount system are analyzed in the frequency domain. Effects of the hydraulic engine mount system running over the rough road are investigated using a vehicle dynamic model. These results are compared with those of the rubber mount system.