• Structural Engineering and Mechanics
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• v.7 no.3
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• pp.289-302
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• 1999

An approximate method for analyzing the bending problems of irregular-shaped plates is proposed. In this paper irregular-shaped plates are such plates as plate with opening, circular plate, semi-circular plate, elliptic plate, triangular plate, skew plate, rhombic plate, trapezoidal plate or the other polygonal plates which are not uniform rectangular plates. It is shown that these irregular-shaped plates can be considered finally as a kind of rectangular plates with non-uniform thickness. An opening in a plate can be considered as an extremely thin part of the plate, and a non-rectangular plate can be translated into a circumscribed rectangular plate whose additional parts are extremely thin or thick according to the boundary conditions of the original plate. Therefore any irregular-shaped plate can be replaced by the equivalent rectangular plate with non-uniform thickness. For various types of irregular-shaped plates the convergency and accuracy of numerical solution by proposed method are investigated.

• 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.

• Structural Engineering and Mechanics
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• v.21 no.6
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• pp.713-735
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• 2005

Due to the complexity of mathematical expressions, the literature concerning the free vibration analysis of plates carrying multiple three-degree-of-freedom (dof) spring-mass systems is rare. In this paper, the three degrees of freedom (dof's) for a spring-mass system refer to the translational motion of its lumped mass in the vertical ($\bar{z}$) direction and the two pitching motions of its lumped mass about the two horizontal ($\bar{x}$ and $\bar{y}$) axes. The basic concept of this paper is to replace each three-dof spring-mass system by a set of equivalent springs, so that the free vibration characteristics of a rectangular plate carrying any number of three-dof spring-mass systems can be obtained from those of the same plate supported by the same number of sets of equivalent springs. Since the three dof's of the lumped mass for each three-dof spring-mass system are eliminated to yield a set of equivalent springs, the total dof of the entire vibrating system is not affected by the total number of the spring-mass systems attached to the rectangular plate. However, this is not true in the conventional finite element method (FEM), where the total dof of the entire vibrating system increases three if one more three-dof spring-mass system is attached to the rectangular plate. Hence, the computer storage memory required by using the presented equivalent spring method (ESM) is less than that required by the conventional FEM, and the more the total number of the three-dof spring-mass systems attached to the plate, the more the advantage of the ESM. In addition, since manufacturing a spring with the specified stiffness is much easier than making a three-dof spring-mass system with the specified spring constants and mass magnitude, the presented theory of replacing a three-dof spring-mass system by a set of equivalent springs will be also significant from this viewpoint.

• Journal of Power System Engineering
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• v.16 no.6
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• pp.38-44
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• 2012

In this paper, the bending characteristics of the corrugated plates is analyzed. The trapezoidally, triangularlly and sinusoidally corrugated plates are considered. The corrugated plate is treated as an orthotropic plate that has different flexural properties in two perpendicular directions. The equivalent bending and twisting rigidities for the equivalent orthotropic plates are derived. The equivalent flexural rigidities are estimated under the following postulations: (1) The angle of continuously corrugated plate is not changed after the deformation. (2) When the pure bending moment is applied in corrugated direction of the plate, the its plane is in pure bending. Several numerical examples are analyzed with the proposed method and compared with published results.

• Journal of electromagnetic engineering and science
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• v.3 no.1
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• pp.72-76
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• 2003

For the purpose of numerically efficient analysis for electrostatic problems, an improved equivalent image method, by which infinite exact image of a point charge in parallel-plate and rectangular conducting structures can be replaced by only a few equivalent images, is considered. Through this study, it is observed that the error is of the order of 0.001 % when the present method is used to evaluate electric potential for a point charge in parallel-plate and rectangular conducting planes.

• Proceedings of the KIEE Conference
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• 1988.07a
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• pp.430-432
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• 1988

Radiation admittance of the rectangular microstrip antenna is calculated by using equivalent ${\pi}$-network parameters of the slit in the wall of the parallel plate waveguide filled with homogeneous dielectric. Using equivalent transmission line model, return loss is calculated and compared with experimental result. Calculated values for the return loss show good agreement with experimental values.

• Structural Engineering and Mechanics
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• v.16 no.3
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• pp.341-360
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• 2003

The goal of this paper is to determine the eigenvalues of a uniform rectangular plate carrying any number of spring-damper-mass systems using an analytical-and-numerical-combined method (ANCM). To this end, a technique was presented to replace each "spring-damper-mass" system by a massless equivalent "spring-damper" system with the specified effective spring constant and effective damping coefficient. Then, the mode superposition approach was used to transform the partial differential equation of motion into the matrix equation, and the eigenvalues of the complete system were determined from the associated characteristic equation. To verify the reliability of the presented theory, all numerical results obtained from the ANCM were compared with those obtained from the conventional finite element method (FEM) and good agreement was achieved. Since the order of the property matrices for the equation of motion obtained from the ANCM is much lower than that obtained from the FEM, the CPU time required by the ANCM is much less than that by the FEM.

• Proceedings of the KIEE Conference
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• 1988.07a
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• pp.433-434
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• 1988

Rectangular microstrip antenna with parasitic element is analyzed. Radiation admittance and equivalent circuit parameters between rectangular microstrip antenna and parasitic element are obtained by using equivalent ${\pi}$-network parameters of the slit in the wall of the parallel plate waveguide filled with homogeneous dielectric. The return loss is calculated and measured as a function of frequency with gap width 0.5mm between the patch and parasitic element. The experimental results are in fairly agreement with calculated values.

• Proceedings of the KSME Conference
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• 2001.11a
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• pp.425-430
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• 2001

The mechanical behavior of two rectangular plates spot-welded under bending is investigated in detail. The focus of the analysis is to evaluate the effect of thickness of reinforced plates with equivalent thickness. The results of this investigation are compared from detailed finite element analysis and experiments of the plates spot-welded for various parameters, such as aspect ratio, area ratio, and distance ratio of spot-welding points. The study is carried out using the equivalent thickness of the reinforced plates spot-welded.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.3
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• pp.387-392
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• 2003

The mechanical behavior of two rectangular spot-welded plates under bending is investigated in detail. The equivalent thickness of spot-welded plates is introduced in this study and used in explaining the results. The focus of the analysis is to evaluate the effect of spot-welding from the view point of equivalent thickness. The investigation of deflection has been performed as comparing the result from finite element analysis with the measured data of the spot-welded plates for various parameters, such as aspect ratio, area ratio, and distance ratio of spot-welding points. The effect of spot-welding is as large as 62%(at r=1.0) when the area ratio of spot-welding point is just 4.52%.