http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Local nanofiller volume concentration effect on elastic properties of polymer nanocomposites
Shin, Hyunseong,Han, Jin-Gyu,Chang, Seongmin,Cho, Maenghyo Techno-Press 2016 Multiscale and multiphysics mechanics Vol.1 No.1
In this study, an influence of local variation of nanoparticulate volume fraction on the homogenized elastic properties is investigated. It is well known that interface effect is dependent on the radius and volume fraction of reinforced nanofillers. However, there is no study on the multiscale modeling and analysis of polymer nanocomposites including polydispersed nanoparticles with consideration of interphase zone, which is dependent on the volume fraction of corresponding nanoparticles. As results of numerical examples, it is confirmed that an influence of local variation of nanoparticulate volume fraction should be considered for non-dilute system such as cluster of nanoparticles. Therefore representative volume element analysis is conducted by considering local variation of nanoparticle volume fraction in order to analyze the practical size of cell including hundreds of nanoparticles. It is expected that this study could be extended to the multiparticulate nanocomposite systems including polydispersed nanoparticles.
Shin, Hyunseong,Kim, Byungjo,Han, Jin-Gyu,Lee, Man Young,Park, Jong Kyoo,Cho, Maenghyo Elsevier Applied Science Publishers 2017 Composites science and technology Vol.145 No.-
<P>We propose a strategy of multiscale analysis to predict enhancements in fracture toughness of thermoplastic/epoxy blends by the plastic yield of toughening agents. As main mechanisms of toughness enhancement of thermoplastic/epoxy blends, we considered plastic deformation in the material near the macroscopic crack tip, and particle bridging in the crack wake. The proposed multiscale model is validated through the reported experimental data. Using the proposed multiscale model, some useful guidelines for the proper selection of toughening agent were devised. (C) 2017 Elsevier Ltd. All rights reserved.</P>
Shin, Hyunseong,Choi, Joonmyung,Cho, Maenghyo Elsevier 2019 Composites science and technology Vol.175 No.-
<P><B>Abstract</B></P> <P>The mechanical characterization of the interphase zone has attracted considerable attention in the fields of mechanical engineering and material design. Especially, the constitutive modeling for the description of the nonlinear mechanical behaviors of the interphase zone within the finite strain is essential for the material design of the polymer nanocomposites (e.g., the thermo-mechanical design, the fracture toughness design, and the fatigue life design). In this study, we propose an efficient multiscale homogenization modeling approach to describe the hyperelastic behavior of the polymer nanocomposites. This is the first attempt to achieve the hyperelastic constitutive modeling of the interphase zone by the multiscale framework, which is based on the full-atomistic molecular dynamics simulations and the multiscale homogenization analysis. The role of interfacial interactions between the nanoparticle and the polymer matrix on the nonlinear mechanical behaviors of polymer nanocomposites is characterized within the finite strain range by the proposed multiscale framework. To overcome the numerical inefficiencies induced by the excessively large number of iterations, the proper orthogonal decomposition method is merged into the proposed multiscale framework. The equivalent continuum models of the polymer nanocomposites are verified by the full atomistic molecular dynamics simulations.</P>
다이 부착용 솔더 재료 내의 미시결함들을 고려한 다중 스케일 열-기계적 해석
신현성(Hyunseong Shin),오철민(Chulmin Oh) 대한기계학회 2017 대한기계학회 춘추학술대회 Vol.2017 No.11
In this study, a multiscale thermo-mechanical analysis framework of die-attach solder material considering microscopic voids is proposed. Microscopic voids cause the degradation of solderability, thermal conductivity, electrical conductivity, and fatigue life. In spite of the significance of the issue, there has been no study on the efficient numerical analysis framework of thermo-mechanical behaviors of die-attach solder material including the small-sized microscopic void (< thickness of solder) as well as relatively large-sized microscopic void. Here, we focus on the effective thermal conductivity and thermal expansion efficient of the solder materials. Micromechanical approach is employed to develop the multiscale framework. In the presentation, the homogenized Anand viscoplastic model, which is widely employed in the thermal fatigue analysis, will be provided. It is expected that this work will be the foundation of the thermo-mechanical design of die-attach solder material.
이동격자와 몬테카를로 전산모사를 통해 미시적 불확실성을 고려한 균질화 기법에 관한 연구
신현성(Hyunseong Shin),장성민(Seongmin Chang),정준호(Joonho Jeong),조맹효(Maenghyo Cho) 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.10
Nano-structures have been widely used due to their high-performances and multi-functionality which comes from size-effect. Surface effect from nano-thickness film, is considered in size-dependent continuum elasticity model. In the real nano-scale structures, however, randomness exists in the size and position of pores or particles because of their tendency to agglomeration and the limits of manufacturing process. Owing to these uncertainties, dispersion of the homogenized material properties occurs. Moreover, the size effect such as surface effect and interphase effect aggravates this dispersion. Therefore, stochastic approach on the nano-structures is necessary to consider the size effect and uncertainties in real nano-structures. In this study, the influence of nano-scale uncertainties on homogenized material properties is considered. Porous materials model including geometric uncertainties are considered in this study. Monte-Carlo simulation is performed to show the distribution of homogenized modulus against uncertainties.
에폭시/PES 복합소재의 인성 향상을 위한 멀티스케일 해석
신현성(Hyunseong Shin),한진규(Jin-Gyu Han),김병조(Byungjo Kim),이만영(Man Young Lee),박종규(Jong Kyoo Park),조맹효(Maenghyo Cho) 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.2015 No.11
Epoxy resins are widely used as phase materials of matrix in fiber-reinforced composites. To overcome brittleness of cross-linked epoxy, thermoplastic modified epoxy has been extensively studied. However, specific toughening mechanism of thermoplastic modified epoxy has not been established in molecular viewpoint. Allegedly, toughening mechanisms of particle debonding, plastic yielding of nanovoids, and localized shear banding are primary origin of fracture toughness enhancement. The purpose of this study is to investigate the contribution of each toughening mechanism. In this study, PES is used as a toughening agent for the cross-linked epoxy composed of TGAP and DDS. Cohesive interface is also considered as it can affect toughening mechanisms. As a result, methodology of construction of finite element PES/epoxy model with cohesive interface is proposed.