• Structural Engineering and Mechanics
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• 제72권6호
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• pp.775-783
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• 2019

The present study deals with the numerical analysis of the symmetric contact problem of two bonded layers resting on an elastic half plane compressed with a rigid punch. In this context, Finite Element Method (FEM) based software called ANSYS and ABAQUS are used. It is assumed that the elastic layers have different elastic constants and heights and the external load is applied to the upper elastic layer by means of a rigid stamp. The problem is solved under the assumptions that the contact between two elastic layers, and between the rigid stamp are frictionless, the effect of gravity force is neglected. To validate the constructed model and obtained results a comparison is performed with the analytical results in literature. The numerical results for normal stresses and shear stresses are obtained for various parameters of load, material and geometry and are tabulated and illustrated.

• Structural Engineering and Mechanics
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• 제15권3호
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• pp.331-344
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• 2003

The plane contact problem for two infinite elastic layers whose elastic constants and heights are different is considered. The layers lying on a Winkler foundation are acted upon by symmetrical distributed loads whose lengths are 2a applied to the upper layer and uniform vertical body forces due to the effect of gravity in the layers. It is assumed that the contact between two elastic layers is frictionless and that only compressive normal tractions can be transmitted through the interface. The contact along the interface will be continuous if the value of the load factor, ${\lambda}$, is less than a critical value. However, interface separation takes place if it exceeds this critical value. First, the problem of continuous contact is solved and the value of the critical load factor, ${\lambda}_{cr}$, is determined. Then, the discontinuous contact problem is formulated in terms of a singular integral equation. Numerical solutions for contact stress distribution, the size of the separation areas, critical load factor and separation distance, and vertical displacement in the separation zone are given for various dimensionless quantities and distributed loads.

• Structural Engineering and Mechanics
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• 제77권1호
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• pp.137-149
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• 2021

In engineering design, the axial equivalent elastic modulus of laminated FRP pipe was mostly calculated by the average elastic modulus method or the classical laminated plate theory method, which are based on relatively simplified assumptions, and may be not accurate enough sometimes. A new analytical calculation method for the axial equivalent elastic modulus of laminated FRP pipe was established based on three-dimensional stress state. By comparing the results calculated by this method with those by the above two traditional analytical methods and the finite element method, it is found that this method for the axial equivalent elastic modulus fits well not only for thin-walled pipes with orthotropic layers, but also for thick-walled pipes with arbitrary layers. Besides, the influence of the layer stacking on the axial equivalent elastic modulus was studied with this method. It is found that a proper content of circumferential layer is beneficial for improving the axial equivalent elastic modulus of the laminated FRP pipe with oblique layers, and then can reduce its material quantity under the premise that its axial stiffness remains unchanged. Finally, the meso-mechanical mechanism of this effect was analyzed. The improving effect of circumferential layer on the axial equivalent elastic modulus of the laminated FRP pipe with oblique layers is mainly because that, the circumferential fibers can restrain the rigid body rotations of the oblique fibers, which tend to cause the significant deformations of the pipe wall units and the relatively low axial equivalent elastic modulus of the pipe.

• Structural Engineering and Mechanics
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• 제48권2호
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• pp.241-255
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• 2013

The receding contact problem for two elastic layers whose elastic constants and heights are different supported by two elastic quarter planes is considered. The lower layer is supported by two elastic quarter planes and the upper elastic layer is subjected to symmetrical distributed load whose heights are 2a on its top surface. It is assumed that the contact between all surfaces is frictionless and the effect of gravity force is neglected. The problem is formulated and solved by using Theory of Elasticity and Integral Transform Technique. The problem is reduced to a system of singular integral equations in which contact pressures are the unknown functions by using integral transform technique and boundary conditions of the problem. Stresses and displacements are expressed depending on the contact pressures using Fourier and Mellin formula technique. The singular integral equation is solved numerically by using Gauss-Jacobi integration formulation. Numerical results are obtained for various dimensionless quantities for the contact pressures and the contact areas are presented in graphics and tables.

• Smart Structures and Systems
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• 제15권6호
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• pp.1411-1437
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• 2015

The electro-magneto- thermo-elastic behavior of a rotating functionally graded long hollow cylinder with functionally graded piezoelectric (FGPM) layers is analytically analyzed. The layers are imperfectly bonded to its inner and outer surfaces. The hybrid cylinder is placed in a constant magnetic field subjected to a thermo-electro-mechanical loading and could be rested on a Winkler-type elastic foundation. The material properties of the FGM cylinder and radially polarized FGPM layers are assumed to be graded in the radial direction according to the power law. The hybrid cylinder is rotating about its axis at a constant angular velocity. The governing equations are solved analytically and then stresses, displacement and electric potential distribution are calculated. Numerical examples are given to illustrate the effects of material in-homogeneity, magnetic field, elastic foundation, applied voltage, imperfect interface and thermo-mechanical boundary condition on the static behavior of a FG smart cylinder.

• 한국정밀공학회지
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• 제28권11호
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• pp.1288-1296
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• 2011

Effective elastic constants of bone-like biocomposites are investigated numerically. The bone-like materials are composed of strong layers and weak layers, and hierarchically structured. The unit cell model is employed to obtain the effective elastic constants. The effective anisotropic elastic constants of bone-like composites are obtained by using the potential energy method and finite element analysis. The effects of the Poisson's ratio, elastic modulus, hierarchical level, volume fraction and aspect ratio of the strong layer composed of the composites on the effective elastic constants are discussed.

• 대한기계학회논문집
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• 제15권5호
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• pp.1538-1550
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• 1991

본 연구에서는 접합된 두 층이 유한한 두께를 가지고, 또한 균열은 임의의 각 도로 기울어져 있는 경우의 문제를 해석하여 층의 두께 등이 응력강도계수에 미치는 영향을 살펴보았다.

• Structural Engineering and Mechanics
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• 제12권1호
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• pp.17-34
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• 2001

The frictionless contact problem for a layered composite which consists of two elastic layers having different elastic constants and heights resting on two simple supports is considered. The external load is applied to the layered composite through a rigid stamp. For values of the resultant compressive force P acting on the stamp vertically which are less than a critical value $P_{cr}$ and for small flexibility of the layered composite, the continuous contact along the layer - the layer and the stamp - the layered composite is maintained. However, if the flexibility of the layered composite increases and if tensile tractions are not allowed on the interface, for P > $P_{cr}$, a separation may be occurred between the stamp and the layered composite or two elastic layers interface along a certain finite region. The problem is formulated and solved for both cases by using Theory of Elasticity and Integral Transform Technique. Numerical results for $P_{cr}$, separation initiation distance, contact stresses, distances determining the separation area, and the vertical displacement in the separation zone between two elastic layers are given.

• Geomechanics and Engineering
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• 제12권2호
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• pp.327-346
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• 2017

Laminated plates have many applications in different industrials. Buckling analysis of these structures with the nano-scale reinforcement has not investigated yet. However, buckling analysis of embedded laminated plates with nanocomposite layers is studied in this paper. Considering the single-walled carbon nanotubes (SWCNTs) as reinforcement of layers, SWCNTs agglomeration effects and nonlinear analysis using numerical method are the main contributions of this paper. Mori-Tanaka model is applied for obtaining the equivalent material properties of structure and considering agglomeration effects. The elastic medium is simulated by spring and shear constants. Based on first order shear deformation theory (FSDT), the governing equations are derived based on energy method and Hamilton's principle. Differential quadrature method (DQM) is used for calculating the buckling load of system. The effects of different parameters such as the volume percent of SWCNTs, SWCNTs agglomeration, number of layers, orientation angle of layers, elastic medium, boundary conditions and axial mode number of plate on the buckling of the structure are shown. Results indicate that increasing volume percent of SWCNTs increases the buckling load of the plate. Furthermore, considering agglomeration effects decreases the buckling load of system. In addition, it is found that the present results have good agreement with other works.

• Structural Engineering and Mechanics
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• 제68권2호
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• pp.203-213
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• 2018

This paper presents a study of geometric nonlinear forced vibration of carbon nano-tubes (CNTs) reinforcement composite plates on nonlinear elastic foundations. The plate is bonded with piezoelectric layers. The von Karman geometric nonlinearity assumptions with classical plate theory are employed to obtain the governing equations. The Galerkin and homotopy perturbation method (HPM) are utilized to investigate the effect of carbon nano-tubes volume fractions, large amplitude vibrations, elastic foundation parameters, piezoelectric applied voltage on frequency ratio and primary resonance. The results indicate that the carbon nano-tube volume fraction, applied voltage and elastic foundation parameters have significant effect on the hardening response of carbon nanotubes reinforced composite (CNTRC) plates.