• Structural Engineering and Mechanics
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• v.72 no.3
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• pp.293-304
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• 2019

In this paper, a general model is developed to predict the distribution of interfacial shear and normal stresses of FG beam reinforced by porous FGM plates under mechanical loading. The beam is assumed to be isotropic with a constant Poisson's ratio and power law elastic modulus through the beam thickness. Stress distributions, depending on an inhomogeneity constant, were calculated and presented in graphicals forms. It is shown that both the normal and shear stresses at the interface are influenced by the material and geometry parameters of the composite beam, and it is shown that the inhomogeneities play an important role in the distribution of interfacial stresses. The results presented in the paper can serve as a benchmark for future analyses of functionally graded beams strengthened by imperfect varying properties plates. Numerical comparisons between the existing solutions and the present new solution enable a clear appreciation of the effects of various parameters. The results of this study indicated that the imperfect functionally graded panel strengthening systems are effective in enhancing flexural behavior of the strengthened FGM beams. This research is helpful in understanding the mechanical behaviour of the interface and design of hybrid structures.

• Structural Engineering and Mechanics
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• v.14 no.3
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• pp.245-262
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• 2002

The free vibration analysis of stiffened laminated composite plates has been performed using the layered (zigzag) finite element method based on the first order shear deformation theory. The layers of the laminated plate is modeled using nine-node isoparametric degenerated flat shell element. The stiffeners are modeled as three-node isoparametric beam elements based on Timoshenko beam theory. Bilinear in-plane displacement constraints are used to maintain the inter-layer continuity. A special lumping technique is used in deriving the lumped mass matrices. The natural frequencies are extracted using the subspace iteration method. Numerical results are presented for unstiffened laminated plates, stiffened isotropic plates, stiffened symmetric angle-ply laminates, stiffened skew-symmetric angle-ply laminates and stiffened skew-symmetric cross-ply laminates. The effects of fiber orientations (ply angles), number of layers, stiffener depths and degrees of orthotropy are examined.

• Earthquakes and Structures
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• v.10 no.2
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• pp.451-461
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• 2016

A new first-order shear deformation theory is developed for dynamic behavior of functionally graded beams. The equations governing the axial and transverse deformations of functionally graded plates are derived based on the present first-order shear deformation plate theory and the physical neutral surface concept. There is no stretching-bending coupling effect in the neutral surface based formulation, and consequently, the governing equations and boundary conditions of functionally graded beams based on neutral surface have the simple forms as those of isotropic plates. The accuracy of the present solutions is verified by comparing the obtained results with the existing solutions.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.3
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• pp.115-122
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• 2002

구조감쇠가 복합적층판의 초음속 패널 플러터에 미치는 영향을 연구하기 위해 에너지법을 활용하여 지배방정식을 유도하였다. 구조 모델링은 일반적인 고전 적층판 이론을 적용하고 이의 해석은 진동 모우드를 가정하는 Rayleigh-Ritz법을 이용하였다. 비정상 공기력은 피스톤 이론(piston theory)을 적용하였다. 구조감쇠가 패널의 플러터에 미치는 일반적인 영향을 고찰하기 위해 등방성 평판의 구조감쇠의 크기에 따른 임계동압을 계산하였으며 이로부터 구조감쇠가 플러터 안정성을 감소시킬 수 있음을 확인하였다. 또한 복합적층판의 적층각에 따른 임계동압을 계산하여 패널 플러터와 구조감쇠와의 관계를 파악하였다. 구조감쇠는 낮은 공력감쇠에서는 플러터 안정성에 중요한 역할을 하지만 높은 공력감쇠에서는 거의 영향을 미치지 않았다.

• Transactions of the Korean Society of Mechanical Engineers
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• v.1 no.3
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• pp.141-145
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• 1977

In this paper, approximate solutions of the von Karman equations for the free flexural vibration of a transversely isotropic thin rectangular plate with two simply supported edges and two clamped edges are obtained. Applying one term Ritz-Galerkin procedure, the spatial dependent part of the equation is separated and time dependent function is found to be the Duffing's equation. Then the relation between nonlinear period and amplitude of the vibration is obtained by using averaging method which is a method of the perturbation procedure. It can be seen that averaging method is easy and agrees well with prior results.

• Structural Engineering and Mechanics
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• v.52 no.6
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• pp.1209-1224
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• 2014

In Current paper, the voltages of patches optimization are carried out for minimizing the power consumption of piezoelectric patches and maximum vertical displacement of symmetrically FML panels using the modified multi-objective Elitist-Artificial Bee Colony (E-ABC) algorithm. The voltages of patches, panel length/width ratios, ply angles, thickness of metal sheets and edge conditions are chosen as design variables. The classical laminated plate theory (CLPT) is considered to model the transient response of the panel, and numerical results are obtained by the finite element method. The performance of the E-ABC is also compared with the PSO algorithm and shows the good efficiency of the E-ABC algorithm. To check the validity, the transient responses of isotropic and orthotropic panels are compared with those available in the literature and show a good agreement.

• Steel and Composite Structures
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• v.15 no.2
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• pp.221-245
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• 2013

This paper presents an analytical solution to the thermomechanical bending analysis of functionally graded sandwich plates by using a new hyperbolic shear deformation theory in which the stretching effect is included. The modulus of elasticity of plates is assumed to vary according to a power law distribution in terms of the volume fractions of the constituents. The core layer is still homogeneous and made of an isotropic ceramic material. The effects of functionally graded material (FGM) layer thickness, volume fraction index, layer thickness ratio, thickness ratio and aspect ratio on the deflections and stresses of functionally graded sandwich plates are investigated.

• Structural Engineering and Mechanics
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• v.63 no.1
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• pp.103-113
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• 2017

Free vibration analysis of plates is necessary for the field of structural engineering because of its wide applications in practical life. Free vibration of plates is largely dependent on its thickness, aspect ratios, and boundary conditions. Here we investigate the natural frequencies of simply supported tapered isotropic rectangular plates with internal cutouts using a nine node isoparametric element. The effect of rotary inertia on Eigenfrequencies was demonstrated by calculating with- and without rotary inertia. We found that rotary inertia has a significant effect on thick plates, while rotary inertia term can be ignored in thin plates. Based on comparison with literature data, we propose that the present formulation is capable of yielding highly accurate results. Internal cutouts at various positions in tapered rectangular simply supported plates were also studied. Novel data are also reported for skew taper plates.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.3 s.174
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• pp.560-566
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• 2000

Many researchers have dealt with the problems of fracture mechanics. Generally, these researches are concerned with crack in isotropic material without other micro defects. Actual structure, however, may contain micro defects as well as crack in manufacture processing or operation. If it contains mi defects near a crack, some different characteristics will be appear in fracture behaviors of the crack. This study examines the effect of the micro defect on stress intensity factor of center slant crack rectangular plate subjected to uniform uniaxial tensile stress. In this study, boundary element method(BEM) is used for analysis in stress intensity factor(SIF).

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.04a
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• pp.393-397
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• 1996

A stewart platform-based force/torque sensor with 6 elastic legs was designed and manufactured Kinematic design parameters were determined so that the force/torque sensor might have the isotropic force/torque properities. In a force/torque analysis, it was used the solution of forward kinematics by linearization of the solution of the inverse kinematics. The performance of te force/torque sensor was investigated by measurement experiments. The gravity compensation was conducted to reduce the force and torque effects by the weights of the upper plate, joints and other sensor parts.