• Nuclear Engineering and Technology
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• v.38 no.7
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• pp.689-696
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• 2006

For a perforated plate, it is challenging to develop a finite element model due to the necessity of the fine meshing of the plate, especially if it is submerged in fluid. This necessitates the use of a solid plate with equivalent material properties. Unfortunately, the effective elastic constants suggested by the ASME code are deemed not valid for a modal analysis. Therefore, in this study the equivalent material properties of a perforated plate are suggested by performing several finite element analyses with respect to the ligament efficiencies.

• Structural Engineering and Mechanics
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• v.55 no.3
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• pp.583-603
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• 2015

There are so many applications of perforated pates with various penetration patterns. If they are penetrated regularly, it can be represented by solid plate with equivalent material properties, which has a benefit of finite element modelling and reducing computation time for the analysis. Because the equivalent material properties suggested already are not proper to be applicable for the dynamic analysis, it is necessary to extract the equivalent material properties for the dynamic analysis. Therefore, in this study, the equivalent modulus of elasticity are obtained for the perforated plate with a triangular penetration pattern by comparing the natural frequencies of the perforated plate with those of solid plate, which are represented with respect to the ligament efficacy. Using the equivalent material properties suggested, the modal analyses of the partially perforated rectangular plate with a triangular penetration pattern are performed and its applicability is shown by comparing natural frequencies of perforated and homogeneous solid plates from finite element method and analytical method.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.15 no.1
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• pp.8-17
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• 2019

Perforated plates are used for the steam generator tube-sheet and the Reactor Vessel Closure Head in the Nuclear Power Plant. The ASME code, Section III Appendix A-8000, addresses the analysis of perforated plates, however, this analysis is only limited to the flat plate with a triangular perforation pattern. Based on the concept of the effective elastic constants, simulation of flat and spherical perforated plates and their equivalent solid plates were carried out using Finite Element Analysis (FEA). The isotropic material properties of the perforated plate were replaced with anisotropic material properties of the equivalent solid plate and subjected to the same loading conditions. The generated curves of effective elastic constants vs ligament efficiency for the flat perforated plate were in agreement with the design curve provided by ASME code. With this result, a plate with spherical curvature having perforations can be conveniently analyzed with equivalent elastic modulus and equivalent Poisson's ratio.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.4 s.235
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• pp.518-525
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• 2005

The electromagnetic noise generates when natural frequencies of a stator core with wingdings and frame coincide with or approach natural frequencies of the magnetic motive force. In order to suppress such noise, the estimation of natural frequencies of the motor is important at the design stage. However, the natural frequency analysis is not so easy because motor stator is in the laminated plate structure and windings are composed of wires, insulation sheets and vanishs. Thus the accurate prediction of the equivalent material properties of windings becomes an essential task. In this paper, we derive the equivalent material properties using homogenization methods.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.10a
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• pp.777-778
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• 2012

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1997.10a
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• pp.1-7
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• 1997

Equivalent thermal conductivities and elasticity properties of woven fabric composites are computed using homogenization technique. The computational results show that the strength and thermal conductivity linearly increase with fiber volume fraction and that the variations of undulation of fibers has little effect on equivalent material properties. Homogenization technique is proved useful in the study of woven fabric composites and may find a lot more applications in the area.

• The Journal of the Acoustical Society of Korea
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• v.30 no.7
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• pp.368-376
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• 2011

Piezoelectric composites have been widely used in broadband acoustic transducers because of their lower acoustic impedance and higher electro-mechanical coupling factor. However, their complex structure has placed many limitations on the design of various transducers. This paper suggests the methodology to substitute the 1-3 piezocomposites by a single-phased material that has properties equivalent to those of the piezocomposites. The resonant method and finite element analysis (FEA) are used to derive the equivalent properties that can accurately depict resonant properties at various vibration modes of the piezocomposites. Validity of the suggested method is confirmed by comparing frequency characteristics of fabricated 1-3 piezocomposite specimens and FEA models. Further, accuracy of the derived material constants is checked by applying the equivalent properties to FEA models of the single phase material for various resonant modes.

• The Journal of the Acoustical Society of Korea
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• v.30 no.8
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• pp.436-445
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• 2011

In this paper, equivalent properties of 2-2 mode piezocomposites were studied. Variation of the properties of 2-2 mode piezocomposites was analyzed by the finite element method, and the result was compared with experimental measurement data to confirm the validity of the analysis. The equivalent properties of a single phase material to represent the piezocomposite composed of PZT-5H and polymer were derived by the asymptotic averaging method. Accuracy of the derived equivalent properties was enhanced by minimizing the discrepancy between the impedance spectra of full 2-2 piezocomposite and equivalent single phase material resonators of various vibration modes by the least square method. The equivalent properties of 2-2 piezocomposites derived in this study can be utilized to the design of diverse acoustic sensors.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.22 no.3
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• pp.588-594
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• 1998

Reliable three-dimensional models of woven fabric composites had scarcely been proposed for their geometric complexity. Simplified models, mostly one- or two-dimensional, currently used are not considered effective enough because of their oversimplifications. In this paper, the equivalent thermal conductivities and elasticity properties of woven fabric composites are computed using homogenization technique. The computational results show that the strength and thermal conductivity linearly increase with fiber volume fraction and that the variations of undulation of fibers has little effect on equivalent material properties. Homogenization technique is proved useful in the study of woven fabric composites and may find a lot more applications in the area.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.37 no.1
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• pp.157-164
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• 2014

The usage of corrugated cardboard for packing material is increasing in these days because it is light and easy to manufacture packing boxes. However, the structure analysis of packing boxes, made of cardboard, is not well carried. The reason can be deduced that its mechanical properties for structure analysis are not well known. The cardboards are made different shapes with various types of raw materials that are paper-based compound. In addition, the cardboards are considered to be orthotropic material. This research finds mechanical properties of triple layered cardboard which is composed of outer liner and inner liner. The moduli of elasticity and of shear for liners are found from tension test and T-Peel test. The mechanical properties of the cardboard are calculated using the super position method and equivalent evaluation method.