• Computational Structural Engineering
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• v.10 no.2
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• pp.225-232
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• 1997

Material properties of a new composite composed of components with known material properties are usually investigated through experiments. Elastic modulus and Poisson's ratio are measured at various volume fractions of mixed components and utilized as the base information on an analytical model for predicting the mechanical behaviors of a structure constructed by the composite. Elastic material properties of a composite at various volume fractions are numerically estimated by minimizing the error between the static displacements computed from a model for the composite and those computed from a model of homogeneous and isotropic material. A finite element model for a composite is proposed to distribute different types of material components easily into the model depending on the volume fraction. Then, the material properties of a composite filled with solid mircospheres are predicted numerically through a sample study and the estimated results are compared with experimental results and some theoretical equations.

• Geomechanics and Engineering
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• v.22 no.1
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• pp.65-80
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• 2020

This paper presents a theoretical investigation on the response of the thermo-mechanical bending of FG plate on variable elastic foundation. A quasi-3D higher shear deformation theory is used that contains undetermined integral forms and involves only four unknowns to derive. The FG plates are supposed simply supported with temperature-dependent material properties and subjected to nonlinear temperature rise. Various homogenization models are used to estimate the effective material properties such as temperature-dependent thermoelastic properties. Equations of motion are derived from the principle of virtual displacements and Navier's solution is used to solve the problem of simply supported plates. Numerical results for deflections and stresses of FG plate with temperature-dependent material properties are investigated. It can be concluded that the proposed theory is accurate and simple in solving the thermoelastic bending behavior of FG thick plates.

• Journal of the Korean Society for Nondestructive Testing
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• v.30 no.6
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• pp.548-557
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• 2010

An ultrasonic resonance scattering spectroscopy technique is developed and applied for reconstructing elastic constants of a transversely isotropic cylindrical component. Immersion ultrasonic measurements are performed on tube samples made from a boron/aluminum composite material to obtain resonance frequencies and dispersion curves of different guided wave modes propagating in the tube. Theoretical analysis on the acoustic resonance scattering from a transversely isotropic cylindrical tube is also performed, from which complete backscattering and resonance scattering spectra and theoretical dispersion curves are calculated. A sensitive change of the dispersion curves to the elastic properties of the composite tube is observed for both normal and oblique incidences; this is exploited for a systematic evaluation of damage and elastic constants of the composite tube samples. The elastic constants of two boron/aluminum composite tube samples manufactured under different conditions are reconstructed through an optimization procedure in which the residual between the experimental and theoretical phase velocities (dispersion curves) is minimized.

• Transactions of Materials Processing
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• v.20 no.6
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• pp.456-460
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• 2011

A major source of difficulty in die design for high strength steel is the high level of elastic recovery during unloading. The degree of elastic recovery is affected by factors such as material strength, bending angle, punch's corner radius and sheet thickness. Finite Element Method was used in the present work to quantitatively analyze the elastic recovery for various combinations of these parameters. In some cases elastic recovery happened in reverse direction. This phenomenon, which we call spring-go, was explained via changes in stress distribution in the panel occurring in the forming process.

• International Journal of Reliability and Applications
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• v.5 no.1
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• pp.1-13
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• 2004

It is recently well recognized that the technique for the one-sided stress wave velocity measurement in structural materials provides measurement in structural materials provides valuable information on the state of the material such as quality, uniformity, location of cracked or damaged area. This technique is especially effective to measure velocities of longitudinal and Rayleigh waves when access to only one surface of structure is possible. However, one of problems for one-sided stress wave velocity measurement is to get consistent and reliable source for the generation of elastic wave. In this study, the laser based surface elastic wave was used to provide consistent and reliable source for the generation of elastic wave into the materials. The velocities of creeping wave and Rayleigh wave in materials were measured by the one-sided technique using laser based surface elastic wave. These wave velocities were compared with bulk wave velocities such as longitudinal wave and shear wave velocities to certify accuracy of measurement. In addition, the mechanical properties such as poisson's ratio and specific modulus(E/p) were calculated with the velocities of surface elastic waves.

• Structural Engineering and Mechanics
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• v.72 no.6
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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.

• Advances in nano research
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• v.5 no.4
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• pp.313-336
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• 2017

This article investigates vibration behavior of magneto-electro-elastic functionally graded (MEE-FG) nanobeams embedded in two-parameter elastic foundation using a third-order parabolic shear deformation beam theory. Material properties of MEE-FG nanobeam are supposed to be variable throughout the thickness based on power-law model. Based on Eringen's nonlocal elasticity theory which captures the small size effects and using the Hamilton's principle, the nonlocal governing equations of motions are derived and then solved analytically. Then the influences of elastic foundation, magnetic potential, external electric voltage, nonlocal parameter, power-law index and slenderness ratio on the frequencies of the embedded MEE-FG nanobeams are studied.

• Journal of Dental Rehabilitation and Applied Science
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• v.25 no.1
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• pp.31-40
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• 2009

The rheologic properties of elastic impression materials is a very important role as taking high accuracy impression. But, the studies that are focused on the rheologic properties of Korean elastic impression materials are not sufficient. The purpose of this study is to help clinical high accuracy impression taking by testing rheologic properties of elastic impression material that is made by Korea and other countries. Six type III elastic impression materials are tested. Subjects are 2 Korean polyvinylsiloxane(PVS), 2 imported PVS, 1 polyether, and 1 polysulfide. HAAKE RheoStress $1^{(R)}$(Thermo Electron Co. Germany)is used in measuring. HAAKE RheoStress $1^{(R)}$ is plate to plate type rheometer. All subjects is tested 3 times and measuring time is 900 seconds. We measured G′ and loss tangent after mixing. All elastic impression materials had a sigmoid shape on increasing G′ by time and decreasing loss tangent after setting, maximum G' is appeared highest in polyether, and lowest in polysulfide. Initial loss tangent is highest in polyether, and is lowest in Koreans PVS. Significant difference is showed in initial loss tangent between Korean PVS and imported PVS.

• Steel and Composite Structures
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• v.34 no.4
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• pp.511-524
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• 2020

In this research, a simple four-variable trigonometric integral shear deformation model is proposed for the static behavior of advanced functionally graded (AFG) ceramic-metal plates supported by a two-parameter elastic foundation and subjected to a nonlinear hygro-thermo-mechanical load. The elastic properties, including both the thermal expansion and moisture coefficients of the plate, are also supposed to be varied within thickness direction by following a power law distribution in terms of volume fractions of the components of the material. The interest of the current theory is seen in its kinematics that use only four independent unknowns, while first-order plate theory and other higher-order plate theories require at least five unknowns. The "in-plane displacement field" of the proposed theory utilizes cosine functions in terms of thickness coordinates to calculate out-of-plane shear deformations. The vertical displacement includes flexural and shear components. The elastic foundation is introduced in mathematical modeling as a two-parameter Winkler-Pasternak foundation. The virtual displacement principle is applied to obtain the basic equations and a Navier solution technique is used to determine an analytical solution. The numerical results predicted by the proposed formulation are compared with results already published in the literature to demonstrate the accuracy and efficiency of the proposed theory. The influences of "moisture concentration", temperature, stiffness of foundation, shear deformation, geometric ratios and volume fraction variation on the mechanical behavior of AFG plates are examined and discussed in detail.

• Journal of Biomedical Engineering Research
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• v.40 no.5
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• pp.158-164
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• 2019

The interbody fusion cage used to replace the degenerative intervertebral disc is largely composed of titanium-based biomaterials and biopolymer materials such as PEEK. Titanium is characterized by osseointergration and biocompatibility, but it is posed that the phenomenon such as subsidence can occur due to high elastic modulus versus bone. On the other hand, PEEK can control the elastic modulus in a similar to bone, but there is a problem that the osseointegration is limited. The purpose of this study was to implement titanium material's stiffness similar to that of bone by applying cellular structure, which is able to change the stiffness. For this purpose, the cellular structure A (BD, Body Diagonal Shape) and structure B (QP, Quadral Pod Shape) with porosity of 50%, 60%, 70% were proposed and the reinforcement structure was suggested for efficient strength reinforcement and the stiffness of each model was evaluated. As a result, the stiffness was reduced by 69~93% compared with Ti6Al4V ELI material, and the stiffness most similar to cortical bone is calculated with the deviation of about 12% in the BD model with 60% porosity. In this study, the interbody fusion cage made of Ti6Al4V ELI material with stiffness similar to cortical bone was implementing by applying cellular structure. Through this, it is considered that the limitation of the metal biomaterial by the high elastic modulus may be alleviated.