• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.8
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• pp.77-84
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• 2003

Structural analyses of a turbine bladed-disk for a liquid rocket turbopump are peformed to investigate the safety level of strength and vibration at design point. Due to the high rotational speed of the turbopump, effects of centrifugal forces are carefully considered in the structural analysis. Thermal load caused by extreme temperature distribution is also considered as an external force applied to turbine bladed-disk. A three dimensional finite element method (FEM) is used for cyclic symmetry structural analyses with the MSC/NASTRAN DMAP Alter. Interblade phase angles are considered to investigate structural dynamic characteristics as a function of rotational speed. Through the numerical analysis, effects of centrifugal and thermal loads on the turbine bladed-disk are examined.

• Aerospace Engineering and Technology
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• v.4 no.1
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• pp.9-17
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• 2005

The aeroelastic stability enhancement of composite hingeless rotor system through the structural damping increase has been investigated. In order to increase structural damping of the rotor system, constrained layer damping (CLD) treatment is applied to the composite flexures. Modal analysis of composite flexures with attached viscoelastic and constraining layers are performed using MSC/NASTRAN, and the effectiveness of CLD treatments are validated through modal test. The composite flexures with CLD are applied to a hingeless rotor system. The rotor system is tested in hovering condition and it is shown that in-plane damping is increased by means of CLD treatments.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.8
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• pp.109-117
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• 2004

A study on gust load alleviation using aircraft control surface was performed. Aeroservoelastic model including control surface controller was formulated and validated by comparing the results of continuous gust response analysis with those of MSC/NASTRAN. Optimal control with output feedback was adopted for designing the control surface controller, and the effects of gust load alleviation was validated by performing the numerical simulation for the controller designed.

• Journal of KSNVE
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• v.6 no.6
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• pp.755-762
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• 1996

An acoustic transmission loss analysis method for mufflers with complex geometry is developed using MSC/NASTRAN on the basis of acoustic-structural analogy and two-microphone method. In this study, mufflers with simple and complex shapes are analyzed using this method and compared with theoretical and experimental results to verify it. Applying this method to design of discharge muffler in a rotary compressor, we obtained 2dB(A) of noise reduction in the range of lower than 1300Hz. Futhermore, adopting this technique for a suction muffler in reciprocal compressor, more than 10dB(A) noise reduction at 500Hz, and in total, 3dB(A) noise reduction is achieved.

• Journal of KSNVE
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• v.6 no.6
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• pp.771-779
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• 1996

In this paper, double Fourier sine series is used as a modal displacement functions of a rectangular plate and applied to the free vibration analysis of a rectangular plate under various boundary conditions. The method of stationary potential energy is used to obtain the modal displacements of a plate. To enhance the flexibility of the double Fourier sine series, Lagrangian multipliers are utilized to match the geometric boundary conditions, and Stokes' transformation is used to handle the displacements that are not satisfied by the double Fourier sine series. The frequency parameters and mode shapes obtained by the present method are compared with those obtained by MSC/NASTRAN and other analysis.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.10a
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• pp.171-177
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• 2011

In this paper, a square simply supported panel flutter have been considered at high supersonic flow by using coupled fluid-structure (FSI) analysis that based on time domain method. The Reynolds-Average Navier Stokes (RANS) equation with Spalart-Allmaras turbulent model were applied for unsteady flow problems of panel flutter. A fully implicit time marching schemed based on the Newmark direct integration method is used for calculating the coupled aeroelastic governing equations of it. In addition, the SOL 145 solver of MSC.NASTRAN was used to investigate flutter velocity based on PK-method of Piston theory. Our numerical results indicated that there is a good agreement result between Piston Theory in MSC.NASTRAN and coupled fluid-structure analysis.

• Proceeding of EDISON Challenge
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• 2015.03a
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• pp.274-278
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• 2015

There are different kinds of aircrafts, such as conventional airplane, rotorcraft, fighter, and unmanned aerial vehicle. Their shape and feature are dependent upon their assigned mission. One of the fundamental analyses during the design of the aircraft is the structural analysis. The structural analysis becomes more complicated and needs more computations because of the on-going complex aircrafts' structure. In order for efficiency in the structural analysis, a simplified approach, such as equivalent beam or plate model, is preferred. However, it is not clear which analysis will be appropriate to analyze the realistic configuration, i.e., an equivalent beam or plate analysis for an aircraft wing. It is necessary to assess the boundary between the one-dimensional beam analysis and the two-dimensional plate theory for an accurate structural analysis. Thus, in this paper, the static structural analysis results obtained by EDISON solvers were compared with the three-dimesional results obtained from MSC NASTRAN. Before that, EDISON program was verified by comparing the results with those from MSC NASTRAN program and analytic solution.

• Aerospace Engineering and Technology
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• v.3 no.1
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• pp.257-266
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• 2004

A three node triangular element with drilling rotations incorporating improved higher-order zig-zag theory(HZZT) is developed to accurately assess the stress distribution through thickness of the laminated plate and analyze the vibration of pretwisted composite plates with embedded damping layer. Shear force matching conditions are enforced along the interfaces between the embedded damping patch and the border patch. The natural frequencies and model loss factors are calculated for cantilevered pretwisted composite blade with damping core with the present triangular element, and compared to experiments and MSC/NASTRAN using a layered combination of plate and solid elements.

• Computational Structural Engineering
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• v.7 no.2
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• pp.61-67
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• 1994

The objective of this numerical analysis is to trace the hysteretic behavior of steel angles under very-low-cycle loading test, especially the history and cumulative state of local stress-strain at their critical parts. The computer model is based on a three-dimensional, non-linear analysis by using the finite element program, MSC/NASTRAN, which includes the effects of the material and geometric non-linearities. The analysis was performed as two stage procedures, namely Analysis I and II. The overall behavior from this analysis showed good agreement with the experiment.

• Journal of Ocean Engineering and Technology
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• v.27 no.2
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• pp.13-18
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• 2013

Most ships and offshore structures are equipped with a variety of pipes, which inevitably contain curved portions. The structural design of these pipes mostly relies on the commercial code, CAESAR-II, which was especially developed for the structural analysis of pipes. This study conducted stress analyses of the same pipe unit, including loops, using both CAESAR-II and MSC/NASTRAN, and compared the results to investigate the characteristics of CAESAR-II. A parametric study was then conducted of the various design variables of pipe loops using CAESAR-II to draw some useful information about the structural characteristics of the loops.