• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.814-819
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• 2003

Machine tool design concepts have evolved towards high efficiency, accurate precision. high structural integrity, and multi-functional systems. Like many other structures, machine tools are also composed of many parts. When these parts are assembled, many kinds of joints are used. In the finite element analysis of these assembled structures, most joints are commonly considered as rigid joints. But, to get the more accurate solution, we need to model these joints in a appropriate manner. In this study, rational dynamic modeling and analysis method for complex structures are studied with special attention to slide way joints. For modeling of slide way joints, a general modeling technique is used by influence coefficients method which is applied to the conversion of detailed finite element model to the equivalent reduced joint model. The theoretical part of this method is illustrated and the method is applied to the structure with slide way joint. In this method. the non-linearity of the contact surfaces is considered within a proper range and the boundary effect of the joint model can be eliminated. The proposed method was applied to finite element modal analysis of a clamp jointed cantilever beam and slide way joints of the vertical type lathe. The method can also be used to other kinds of joint modeling. The results of these analysis were compared with those of Yoshimura models and rigid joint models. which demonstrated the practical applicability of the proposed method.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11a
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• pp.498-498
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• 2001

Seismic qualification of the Main Control Boards for nuclear power plants has been performed with the guideline of AS ME Section III. US NRC Reg. Guide and IEEE 344 code. The analysis model of the Main Control Boards is consist of beam. shell and mass element by using the finite element method. and, at the same time. the excitation forces and other operating loads for each model are encompassed with respect to different loading conditions. As the fundamental frequencies of the structure are found to be less than 33Hz. which is the upper frequency limit of the seismic load, the response spectrum analysis using ANSYS is performed in order to combine the modal stresses within the frequency limit. In order to confirm the structural and functional integrity of the major components, modal analysis theory is adopted to derive the required response spectrum at the component locations. As all the combined stresses obtained from the above procedures are less than allowable stresses and no mechanical or electrical failures are found from the seismic testing, it concludes the Main Control Boards is dynamically qualified for seismic conditions. Although the authors had confirmed the structural and functional integrity of both Main Control Boards and all the component, in this paper only the seismic analysis of the Main Control Board is introduced.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.10 s.181
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• pp.2619-2627
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• 2000

In this paper, the vibrational characteristics of a foot mount type gearbox for epicyclic gear train have been studied. The modal parameters and mode shapes of a gearbox have been computed using AN SYS code. Modal testing was carried out to verify the FEM analysis model. It has been shown that the analysis results are in good agreements with the experimental results. Harmonic analysis has been executed to verify the effect of thickness variance of gearbox housing on the modal response. Analyzing the calculated results, some guides for optimal vibration response has been deduced.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.837-842
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• 2000

In this Paper, the vibrational characteristics of a gearbox for epicyclic Rear train have been studied The modal parameters and mode shapes of a gearbox have been computed using ANSYS code. Modal testing was carried out to verity the FEM analysis model. It has been shown that the analysis results are m good agreements with the experimental results. Harmonic analysis has been executed to verify the effect of thickness variance of gearbox housing on the modal response. Analyzing the calculated results, some guides fer optimal vibration response has been deduced.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.192-195
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• 2005

In this study, dynamic characteristics of an end-capped hull structure with surface bonded piezoelectric actuators are studied. Finite element modeling is used to obtain practical governing equation of motion and boundary conditions of smart hull structure. Modal analysis is conducted to investigate the dynamic characteristics of the hull structure. Piezoelectric actuators are attached where the maximum control performance can be obtained. Active controller based on Linear Quadratic Gaussian (LQG) theory is designed to suppress vibration of smart hull structure. It is observed that closed loop damping can be improved with suitable weighting factors in the developed LQG controller.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.947-950
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• 2007

In this study, vibration analysis of a refrigerator was carried out to reduce vibration by considering grommet. When the refrigerator machine room is modeled by finite element method, spring elements are added to constructions of the FEmodel for each component and update. To design the grommet of refrigerator, FEmodel must have vibration characteristics of each components such as baseplate, pipe and compressor it self. The modal analyses are conducted to validate suggested approach when the components of machine room are assembled together. And, in this study, optimal design of grommet is conducted to avoid the resonance at the operating frequency of refrigerator. The experimental and FEM result of suggested design showed good agreement and are presented here.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.4 s.121
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• pp.317-323
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• 2007

Non-contact underwater explosions against surface ships could cause extensive equipment damage and render the ship inoperative. As an analytical method, DDAM(dynamic design and analysis method) is used for ship shock design. In this paper, in order to verify the finite element model of large shipboard equipment, modal test of equipment was performed. Major objective of this paper is to describe shock analysis methodology for large shipboard equipment attacked to the top and bottom foundations.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.7 s.124
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• pp.587-595
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• 2007

Performance evaluation of advanced piezoelectric composite actuator is conducted with its application of structural vibration control. Characteristics of MFC(macro fiber composite) actuator are investigated by comparing traditional piezoceramic patch actuator. Finite element modeling is used to obtain equations of motion and boundary effects of smart hull structure with MFC actuator. Dynamic characteristics of the smart hull structure are studied through modal analysis and experimental investigation. LQG control algorithm is employed to investigate active damping of hull structure. It is observed that vibration of hull structure is suppressed effectively by the MFC actuators.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.1119-1124
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• 2007

Performance evaluation of advanced piezoelectric composite actuator is conducted with its application of structural vibration control. Characteristics of MFC (macro fiber composite) actuator are investigated by comparing traditional piezoceramic patch actuator. Finite element modeling is used to obtain equations of motion and boundary effects of smart hull structure with MFC actuator. Dynamic characteristics of the smart hull structure are studied through modal analysis and experimental investigation. LQG control algorithm is employed to investigate active damping of hull structure. It is observed that vibration of hull structure is suppressed effectively by the MFC actuators.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.12 s.105
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• pp.1408-1415
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• 2005

Active vibration control of smart hull structure using Macro Fiber Composite (MFC) actuator is performed. Finite element modeling is used to obtain governing equations of motion and boundary effects of end-capped smart hull structure. Equivalent interdigitated electrode model is developed to obtain piezoelectric couplings of MFC actuator. Modal analysis is conducted to investigate the dynamic characteristics of the hull structure, and compared to the results of experimental investigation. MFC actuators are attached where the maximum control performance can be obtained. Active controller based on Linear Quadratic Gaussian (LQG) theory is designed to suppress vibration of smart hull structure. It is observed that closed loop damping can be improved with suitable weighting factors in the developed LQG controller and structural vibration is controlled effectively.