• Computational Structural Engineering
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• v.15 no.3
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• pp.5-14
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• 2002

• Journal of the KSME
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• v.57 no.6
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• pp.42-46
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• 2017

이 글에서는 거시소재와 나노소재의 소성 거동이 상이한 이유에 대해 간략히 논하고, 전산역학을 이용한 금속나노소재의 소성 변형 메커니즘 연구를 면심입방 소재의 예를 통해 소개하고자 한다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.3
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• pp.287-292
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• 2007

In general, the response of bulk material is independent of its size when it comes to considering classical elasticity theory. Because the surface to bulk ratio of the large solids is very small, the influence of surface can be negligible. But the surface effect plays important role as the surface to bulk ratio becomes larger, that is, the contribution of the surface effect must be considered in nano-size elements such as thin film or beam structure. Molecular dynamics computation has been a conventional way to analyze these ultra-thin structures but this method is limited to simulate on the order of $10^6{\sim}10^9$ atoms for a few nanoseconds, and besides, very time consuming. Analysis of structures in submicro to micro range(thin-film, wire etc.) is difficult with classical molecular dynamics due to the restriction of computing resources and time. Therefore, in this paper, the continuum-based method is considered to simulate the overall physical and mechanical properties of the structures in nano-scale, especially, for the thin-film.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.22 no.4
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• pp.343-348
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• 2009

In this study, an efficient sequential bridging method to characterize both the particle size effect and concentration effect on the mechanical properties of nanocomposites at high volume fraction is suggested through a molecular dynamics(MD) simulations and micromechanics of composites materials. The Young's modulus and the shear modulus of the nanocomposites at various particle radius and at 12% volume fraction were obtained from MD simulations and multi-inclusion model was adopted to describe both modulus in continuum model. In order to describe the particle size effect, an additional phase, effective interface, was adopted as characteristic phase and the non-dilute concentration effect which appears at 12% volume fraction was describe via the variation of the elastic modulus of the infinite medium. Both the elastic modulus of the interface and infinite medium were fitted into functions of particle radius for the applicability of the present bridging method at various particle radii. Using the present bridging method the elastic modulus of the nanocomposites was efficiently obtained with accuracy. In addition, the effect of the interface thickness and modulus on the elastic modulus of the nanocomposite was investigated.

• Membrane Journal
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• v.32 no.1
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• pp.57-65
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• 2022

Recently, computer simulation research has been rapidly increasing due to the development of computer and software technology. In particular, various computational simulation results related to polymers, which were previously limited by problems of the number of atoms and model size, are being published. In this study, a study was conducted to analyze the mechanical properties, one of the important properties for using a polymer material as a membrane, using molecular dynamics (MD) simulation. To this end, polyethylene (PE) and polystyrene (PS), which are commercial polymer materials with widely reported related properties, were selected as polymer models and the tensile properties of each polymer were compared through the difference in main chain length. Through the density, radius of gyration, and scattering analysis, it was found that the model produced in this study was in good agreement with the mechanical property trends obtained in the actual experiment. It is expected to enable the prediction of mechanical properties of various polymer materials for membrane fabrication.

• Journal of the KSME
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• v.44 no.3
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• pp.70-78
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• 2004

이 글에서는 MD 전산모사를 통해 합성거동의 원자규모 해석, 계면에서의 원자혼합 거동, 박막 구조의 원자규모 분석 및 박막 물성과의 관계규명이 가능함을 소개하고, 또한, 탄소에 관한 Tersoft 포텐셜 함수의 한계로부터 포텐셜 함수의 개선이 필요함을 보여준다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.15 no.4
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• pp.168-174
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• 2005

In this study, the numerical simulation of drying processes for porous materials is performed by employing the hierarchical multi-scale modeling and the nano-scale material properties obtained from the molecular dynamics simulation. The multi-scale simulation system is set up using pre- and post-processors and the drying process of electric porous ceramic insulator is simulated. The temperature, moisture, residual stress, and displacement distributions are compared with those based on homogenized properties.

• Ceramist
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• v.3 no.4
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• pp.32-45
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• 2000

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.506-511
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• 2007

Mechanical behavior of copper nanowire is investigated. An FCC nanowire model composed of 1,408 atoms is used for MD simulation. Simulations are performed within NVT ensemble setting without periodic boundary conditions. $Nos\acute{e}-Poincar\acute{e}$ MD algorithm is employed to guarantee preservation of Hamiltonian and temperature. Numerical tensile tests of Nanowire are carried out with constant strain rate. Additionally, temperature and strain rate effects are considered. Stress-strain curve is constructed from the calculated Cauchy stresses and specified strain values. In (22,4,4) Copper nanowire, non-linear behavior appears around ${\epsilon}\simeq0.09.$ At this instance, starting of structural reorientations are observed. At the onset of reorientation, the modulus characteristics are also investigated.

• Composites Research
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• v.28 no.5
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• pp.260-264
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• 2015

In this paper, molecular dynamics (MD) simulation was carried to predict thermo-mechanical behaviors for carbon nanotube (CNT) reinforced epoxy composites and to analyze the trends. Total of six models having the volume fractions of CNT from 0 to 25% in epoxy were constructed. To predict thermal behaviors, temperature was increased constantly from 300 to 600 K, and the glass transition temperature ($T_g$) and coefficient of thermal expansion (CTE) analyzed using the relationship between temperature and specific volume. The elastic moduli that represented to the mechanical behaviors were also predicted by constant strain. Additionally, the effects of functionalization of CNT on mechanical behaviors of composite were analyzed. Models were constructed to represent CNTs functionalized by nitrogen doping and COOH groops, and interfacial behaviors and elastic moduli were analyzed. Results showed that the agglomerations of CNTs in epoxy cause by perturbations of thermo-mechanical behaviors, and the functionalization of CNTs improved the interfacial response as well as mechanical properties.