• Geomechanics and Engineering
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• 제8권3호
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• pp.305-321
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• 2015

In this paper, a new hyperbolic shear deformation plate theory based on neutral surface position is developed for the static analysis of functionally graded plates (FGPs). The theory accounts for hyperbolic distribution of the transverse shear strains and satisfies the zero traction boundary conditions on the surfaces of the beam without using shear correction factors. The neutral surface position for a functionally graded plate which its material properties vary in the thickness direction is determined. The mechanical properties of the plate are assumed to vary continuously in the thickness direction by a simple power-law distribution in terms of the volume fractions of the constituents. Based on the present new hyperbolic shear deformation plate theory and the neutral surface concept, the governing equations of equilibrium are derived from the principle of virtual displacements. Numerical illustrations concern flexural behavior of FG plates with Metal-Ceramic composition. Parametric studies are performed for varying ceramic volume fraction, volume fraction profiles, aspect ratios and length to thickness ratios. The accuracy of the present solutions is verified by comparing the obtained results with the existing solutions.

• Wind and Structures
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• 제22권3호
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• pp.291-305
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• 2016

In this paper, a refined shear deformation plate theory which eliminates the use of a shear correction factor was presented for FG sandwich plates composed of FG face sheets and an isotropic homogeneous core. The theory accounts for parabolic distribution of the transverse shear strains and satisfies the zero traction boundary conditions on the surfaces of the plate. The mechanical properties of the plate are assumed to vary continuously in the thickness direction by a simple power-law distribution in terms of the volume fractions of the constituents. Based on the present refined shear deformation plate theory, the governing equations of equilibrium are derived from the principle of virtual displacements. Numerical illustrations concern buckling behavior of FG sandwiches plates with Metal-Ceramic composition. Parametric studies are performed for varying ceramic volume fraction, volume fraction profiles, Boundary condition, and length to thickness ratios. The accuracy of the present solutions is verified by comparing the obtained results with the existing solutions.

• 한국자동차공학회논문집
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• 제4권6호
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• pp.18-26
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• 1996

A two dimensional thermo elasto-plastic finite element stress analysis was performed to study residual stress distributions in AI composites reinforced by SiC whisker and $ZrO_2$ ceramic joints. The influences on the residual stress distributions due to the difference of the reinforcement volume fraction and interlayer material property were investigated. Specifically, stress distributions between AI interlayer material property were investigated. Specifically, stress distributions between AI interlayer and $ZrO_2$ ceramic and between the AI interlayer and AI composite were computationally analzed.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2001년도 추계학술발표대회 논문집
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• pp.144-148
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• 2001

A proper estimation of the mechanical properties for composites has been required for better design/selection of constituents for composite materials. Present investigation shows the simulation results for ceramic reinforced metal matrix composite under uniaxial transverse tensile loading. The resulting transverse mean stress with the transverse mean strain was described for composites as a function of the volume fraction with two different types of interfacial bonding: (1)strongly bonded interface, and (2)no bonded interface. A two-dimensional finite element modeling and analysis were conducted based on the unit-cell concept with an assumption of a regular square arrangement of the reinforcement within the composite. The mean stress was generally increased with the ceramic volume fraction for composite with strong interface bonding. The micromechanics concept combined with finite element modeling for composite can be used in order to predict the transverse properties of composites with a priori known properties of constituents.

• 동력기계공학회지
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• 제10권4호
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• pp.133-138
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• 2006

Effective thermal conductivity of particulate reinforced composite has been predicted by Eshelby's equivalent inclusion method modified with Mori-Tanaka's mean field theory. The predicted results are compared with the experimental results from the literature. The model composite is polymer matrix filled with ceramic particles such as silica, alumina, and aluminum nitride. The preliminary examination by Eshelby type model shows that the predicted results are in good agreements with the experimental results for the composite with perfect spherical filler. As the shape of filler deviates from the perfect sphere, the predicted error increases. By using the aspect ratio of the filler deduced from the fixed filler volume fraction of 30%, the predicted results coincide well with the experimental results for filler volume fraction of 40% or less. Beyond this fraction, the predicted error increases rapidly. It can be finally concluded from the study that Eshelby type model can be applied to predict the thermal conductivity of the particulate composite with filler volume fraction less than 40%.

• 한국세라믹학회지
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• 제33권8호
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• pp.855-862
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• 1996

The nucleation and the crystal growth rates of Ge-Se-Te chalcogenide glass by two step heat-treatment and its effect on the mechanical optical properties and water-resistance were determined. The maximum nuclea-tion and crystal growth rate were 2.1$\times$103/mm3 .min at 28$0^{\circ}C$ and 0.4${\mu}{\textrm}{m}$/min at 33$0^{\circ}C$ respectively. When the crystal volume fraction with crystal size $1.5mutextrm{m}$ was about 4% the (hardness and fracture toughness were about 117kg/mm2 and 6.0 MPa.mm1/2)respectively. The weight loss of crystallized glass in water was lower than parent glass($25^{\circ}C$ for 32 hrs : 0.03% 8$0^{\circ}C$ for 16 hrs : 0.1%) as 0.01% at $25^{\circ}C$, 0.03% at 8$0^{\circ}C$ for 16 hrs : 0.1%) at $25^{\circ}C$ 0.03% at 8$0^{\circ}C$ respectively. The IR-transmittance decreased with increasing crystal size and crystal volume fraction. The IR-transmittance of crystallized glass with the crystal size of $1.5mutextrm{m}$ (crystal volume fraction : 4%) presented 56% which was about 4% lower than that of parent glass.

• Smart Structures and Systems
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• 제29권3호
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• pp.387-393
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• 2022

This paper presents the vibration analysis of cracked ceramic-reinforced aluminum composite beams by using a method based on changes in modal strain energy. The crack is considered to be straight. The effective properties of composite materials of the beams are estimated through Mori-Tanaka micromechanical model. Comparison study and numerical simulations with various parameters; ceramic volume fraction, reinforcement aspect ratio, ratio of the reinforcement Young's modulus to the matrix Young's modulus and ratio of the reinforcement density to the matrix density are taken into investigation. Results demonstrate the pronounced effects of these parameters on intact and cracked ceramic aluminum beams.

• Steel and Composite Structures
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• 제52권5호
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• pp.583-593
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• 2024

The present paper deals with the dynamic analysis of cracked ceramic-reinforced aluminum composite fixed beams by using a method based on changes in modal strain energy. Mechanical characteristics of composite materials of the beams are predicted through Mori-Tanaka micromechanical scheme. A Comparative study and numerical simulations involve various parameters; ceramic volume fraction, reinforcement aspect ratio, ratio of the reinforcement Young's modulus to the matrix Young's modulus and ratio of the reinforcement density to the matrix density are taken into investigation. The obtained results prove the important effects of these parameters on intact and cracked ceramic aluminum beams.

• 한국세라믹학회지
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• 제35권9호
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• pp.988-994
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• 1998

In the manufacturing of vitreous bonded CBN tool the porosity change associated with various processing conditions, I. e. the sintering temperature and the size and the amount of abrasive grits was observed. In the case of sintering of vitreous bond material only the specimen density reached the maximum at 950$^{\circ}C$ and then the total porosity was increased slightly with the temperature above 950$^{\circ}C$. In the sintering of a-brasive grits and the vitreous bond material together a marked increase in the total porosity was found with the temperature above 950$^{\circ}C$ Reducing the grit size at the constant volume fraction of abrasive grits showed an increase in the total porosity at whole sintering temperature. On the contrary. it was observed that increasing the volume fraction of abrasive grits with a same size showed the increased open porosity simultaneously with decreased closed porosity at whole sintering temperature.

• 한국안전학회지
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• 제13권2호
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• pp.45-53
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• 1998

A method to predict the creep behavior of fiber-reinforced ceramic composites at high temperatures was suggested based on finite element modeling using constituent creep equations of fiber and matrix and showed good agreement with the experimental results. The effects of matrix creep behavior, fiber volume fraction, and residual stresses on the composite creep behavior were also investigated. The results showed that the primary behavior of composites was greatly affected by that of matrix but post-primary behavior was governed by fiber creep characteristics. The increase of fiber volume fraction from 15 vol% to 30 vol% caused the 50% and 40% decrease of steady-state creep rates and total creep strains at $1200^{\circ}C$, 180MPa, respectively. Feasible compressive residual stresses in the matrix caused by different thermal expansion coefficients between the fiber and the matrix could significantly reduce total creep strains of the composite. The creep deformation mechanism in the fiber-reinforced ceramic composites could be explained by the stress transfer and redistribution in the fiber and matrix due to different creep characteristics of its constituents.