• Nuclear Engineering and Technology
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• v.41 no.3
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• pp.355-364
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• 2009

Circular plates with holes are extensively used in mechanical components. The existence of a hole in a circular plate results in a significant change in the natural frequencies and mode shapes of the structure. Especially if the hole is located eccentrically, the vibration behavior of these structures is expected to deviate significantly from that of a plate with a concentric hole. In addition, if the plate is in contact with or submerged in fluid, the situation is more complex. Therefore, in this study, an analytical method to determine the modal characteristics of a plate submerged in fluid is developed based on the finite Fourier-Bessel series expansion and Rayleigh-Ritz method and is verified by the finite element analysis using a commercial program. Also, the relationship between parameter variations and vibration modes is investigated. These results can be used as guidance for the modal analysis and damage detection of a circular plate with a hole.

• Steel and Composite Structures
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• v.17 no.1
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• pp.1-19
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• 2014

Buckling and vibration characteristics of circular laminated plates under in-plane edge loads and resting on Winkler-type foundation are solved by the Ritz method. Inclusive numerical data are presented for the first three eigen-frequencies as a function of in-plane load for different classical edge conditions. Moreover, the effects of fiber orientation on the natural frequencies and critical buckling loads of laminated angle-ply plates with stacking sequence of $[({\beta}/-{\beta}/{\beta}/-{\beta})]_s$, are studied. Also, selected deformation mode shapes are illustrated. The correctness of results is established using finite element software as well as by comparison with the existing results in the literature.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.2
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• pp.387-395
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• 1991

Large deflection behavior of cylindrically orthotropic thin circular plates is investigated by the numerical technique of differential quadrature. Governing equations are derived in terms of transverse deflection and stress function and a Newton-Raphson technique is used to solve the nonlinear systems of equations. For small values of degree of differential quadrature (N.leq.13), as the degree of differential quadrature increases, the center deflection converges. However, as N increases further, the center deflection diverges by ill-conditioning in the weighting coefficients. As the orthotropic parameter increases, the center deflection decreases and behaves linear for the loads. At center, the stress is affected mainly by orthotropic parameter, while the stress is affected mainly by boundary condition at edge.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.7
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• pp.147-155
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• 2000

To reduce the noise from wood cutting saw at the saw mill(lumber mill) or a construction area, some multi-layer sandwich saw blades which a aluminum or copper plate was inserted between the two steel plates were developed and were tested of the wood cutting noise level at various test places. From the research, it was found that the multi-layer saw blade with copper or aluminum plate between steel plates and spot welded 60 points could reduce the wood cutting sound level about 8.3 dB(97.031 dB - 88.743 dB) at indoor test and 3.8 dB(84.805 - 81.638 dB) at field test.

• Structural Engineering and Mechanics
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• v.15 no.2
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• pp.249-267
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• 2003

In this study, circular plates subjected to general type of loads and supported on a two-parameter elastic foundation are analysed. The stiffness, elastic bedding and soil shear effect matrices of a fully compatible ring sector plate element, developed by Saygun (1974), are obtained numerically assuming variable thickness of the element. Ring sector soil finite element is also defined to determine the deflection of the soil surface outside the domain of the plate in order to establish the interaction between the plate and the soil. According to Vallabhan and Das (1991) the elastic bedding (C) and shear parameters ($C_T$) of the foundation are expressed depending on the elastic constants ($E_s$, $V_s$) and the thickness of compressible soil layer ($H_s$) and they are calculated with a suitable iterative procedure. Using ring sector elements presented in this paper, permits the generalization of the loading and the boundary conditions of the soil outside the plate.

• Structural Engineering and Mechanics
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• v.77 no.2
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• pp.245-259
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• 2021

In this research, the influence of the laminate stacking sequence on thermal stress distribution in symmetric composite plates with a quasi-square cutout subjected to uniform heat flux is examined analytically using the complex variable technique. The analytical solution is obtained based on the thermo-elastic theory and the Lekhnitskii's method. Furthermore, by employing a suitable mapping function, the solution of symmetric laminates containing a circular cutout is extended to the quasi-square cutout. The effect of important parameters including the stacking sequence of laminates, the angular position, the bluntness, the aspect ratio of cutout, the flux angle and the composite material are examined on the thermal stress distribution. It is found out that the circular shape for cutout may not necessarily be the optimum geometry for all stacking sequences. The finite element analysis results are used to validate the analytical solution.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.5
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• pp.403-411
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• 2016

Usually shell and tube heat exchangers are employed to recover energy between fluids. Recently, numerous papers on these heat exchangers have been published; however, the velocity and temperature profiles or comparison of the features of the flow with or without inside tubes have rarely been described. In this research, experimental and numerical studies were carried out to investigate the characteristics of the flow around the spiral baffle plates without inside tubes in a horizontal circular tube using a particle image velocimetry method and ANSYS 14.0~15.0 version (Fluent). The results showed that swirling flow was produced between the spiral baffle plates. The tangential components were strong between the two spiral baffles; however, the axial or radial velocities components were indicating nearly zero. From the spiral motion in the space of the two baffles, it is considered that there were no dead zones between the spiral baffle.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.2
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• pp.127-134
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• 2004

Control of drag force on a circular cylinder using multiple detached splitter plates is numerically studied for laminar flow Two splitter plates with the same length as the cylinder diameter (d) are placed horizontally in the upstream of the cylinder and in the near-wake region, respectively. Their positions are described by the gap ratios (G$_1$/d, G$_2$/d), where G$_1$ represents the gap between the cylinder stagnation point and the rear edge of the upstream splitter plate, and G$_2$ represents the gap between the cylinder base point and the leading edge of the rear splitter plate. The drag varies with the two gap ratios; it has the minimum value at a certain set of gap ratios for each Reynolds number The upstream splitter plate decreases the stagnation pressure, while the rear splitter plate increases the base pressure by suppressing vortex shedding. This combined effect causes a significant drag reduction on the cylinder Particularly, the drag sharply increases past an optimum G$_2$/d; this seems to be related to a sudden change in bubble size in the wake region.

• Korean Journal of Optics and Photonics
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• v.25 no.3
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• pp.150-154
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• 2014

The conditions under which a composite retarder consisting of two different retardation plates can be operated as a tunable quarter-wave plate are derived. The explicit expressions for the azimuthal angle of a linear polarizer and those of two retardation plates to generate circularly polarized light are presented as a function of retardation angles. Those expressions for the azimuthal angles derived using the Jones matrix formalism are verified as identical to the expressions derived from the analysis of the trajectory on a Poincar$\acute{e}$ sphere. A couple of examples are presented for generating circularly polarized light when two identical retardation plates are used.

• Structural Engineering and Mechanics
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• v.83 no.6
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• pp.757-770
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• 2022

In this paper, the vibration of a moderately thick plate to a moving mass is investigated. Pasternak foundation with a variable subgrade modulus is considered to tackle the shortcomings of Winkler model, and an analytical-numerical solution is proposed based on the eigenfunction expansion method. Parametric studies by using both CPT (Classical Plate Theory) and FSDT (First-Order Shear Deformation Plate Theory) are carried out, and, the differences between them are also highlighted. The obtained results reveal that utilizing FSDT without considering the rotary inertia leads to a smaller deflection in comparison with CPT pertaining to a thin plate, while it demonstrates a greater response for plates of higher thicknesses. Moreover, it is shown that CPT is unable to properly capture the variation of the plate thickness, thereby diminishing the accuracy as the thickness increases. The outcomes also indicate that the presence of a foundation contributes more to the dynamic response of thin plates in comparison to moderately thick plates. Furthermore, the findings suggest that the performance of the moving force approach for a moderately thick plate, in contrast to a thin plate, appears to be acceptable and it even provides a much better estimation in the presence of a foundation.