• Title/Summary/Keyword: composed material model

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AHP-Based Evaluation Model for Optimal Selection Process of Patching Materials for Concrete Repair: Focused on Quantitative Requirements

  • Do, Jeong-Yun;Kim, Doo-Kie
    • International Journal of Concrete Structures and Materials
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    • v.6 no.2
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    • pp.87-100
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    • 2012
  • The process of selecting a repair material is a typical one of multi-criteria decision-making (MCDM) problems. In this study Analytical Hierarch Process was applied to solve this MCDM problem. Many factors affecting a process to select an optimal repair material can be classified into quantitative and qualitative requirements and this study handled only quantitative items. Quantitative requirements in the optimal selection model for repair material were divided into two parts, namely, the required chemical performance and the required physical performance. The former is composed of alkali-resistance, chloride permeability and electrical resistivity. The latter is composed of compressive strength, tensile strength, adhesive strength, drying shrinkage, elasticity and thermal expansion. The result of the study shows that this method is the useful and rational engineering approach in the problem concerning the selection of one out of many candidate repair materials even if this study was limited to repair material only for chloride-deteriorated concrete.

Analysis of Heat-transfer on Winding composed with Epoxy-resin (에폭시수지로 몰딩된 권선의 열전달 특성 연구)

  • 이현진;허창수;조한구;이기택;서유진
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2002.07a
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    • pp.402-405
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    • 2002
  • This paper presented the characteristic of Heat-transfer on the winding composed with Epoxy-resin in a 50 kVA cast-resin dry type transformer The resin cast transformer is used widely in supplying electricity systems. However, to know the thermal characteristics of that is very useful in designing, manufacturing, and maintaining, there is no pertinent method to calculate this. In this paper, Based on the results of the physical characteristics and the simulation by commercial software using FEM method, we established the Prototype Model for this. According to that Model, an analysis on a variation of the hottest spot temperature was discussed as a function of thermal conductivity for the individual windings composed with Epoxy-resin. The thermal conductivity of the individual windings with reference to upper way was discussed.

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Development of Multi-Material DLP 3D Printer (다중재료 DLP 3차원 프린터의 개발)

  • Park, Se-Won;Jung, Min-Woo;Son, Yong-Un;Kang, Tae-Young;Lee, Chibum
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.26 no.1
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    • pp.100-107
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    • 2017
  • 3D printing is a technology that converts a computer-generated 3D model into a real object with additive manufacturing technology. A majority of 3D printing technologies uses one material, and this is considered a limitation. In this study, we developed a multi-material 3D printer by adopting dual resin vat and cleaning system with DLP (Digital Light Processing) 3D printing technology. The developed multi-material DLP 3D printer is composed of a manufacturing system, cleaning system, transporting system, and automatic resin recharging system. Various 3D structures were 3D printed with two materials, thus demonstrating the potential. Printing performance of the multi-material DLP 3D printer was studied by performing a comparative surface roughness test and tension test on specimens composed of one material as well as those composed of two materials.

Mechanical strength analysis for functionally graded composite plates (경사기능 복합재료 판의 기계적 강도해석)

  • Na, Kyung-Su;Kim, Ji-Hwan
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2005.11a
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    • pp.66-69
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    • 2005
  • Mechanical strength of functionally graded composite plates that composed of ceramic, functionally graded material and metal layers is investigated using 3-D finite element method. In FGM layer, material properties are assumed to be varied continuously in the thickness direction according to a simple power law distribution in terms of the volume fraction of a ceramic and metal. The 3-D finite element model is adopted by using an IS-node solid element to analyze more accurately the variation of material properties in the thickness direction. Numerical results are compared with those of the previous works. In addition, the displacements, the tensile stresses and the compressive stresses are analyzed for the variation of FGM thickness ratio and volume fraction distribution.Mechanical strength of functionally graded composite plates that composed of ceramic, functionally graded material and metal layers is investigated using 3-D finite element method. In FGM layer, material properties are assumed to be varied continuously in the thickness direction according to a simple power law distribution in terms of the volume fraction of a ceramic and metal. The 3-D finite element model is adopted by using an IS-node solid element to analyze more accurately the variation of material properties in the thickness direction. Numerical results are compared with those of the previous works. In addition, the displacements, the tensile stresses and the compressive stresses are analyzed for the variation of FGM thickness ratio and volume fraction distribution.

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Composed material models for nonlinear behavior of reinforced concrete

  • Dede, Tayfun;Ayvaz, Yusuf
    • Computers and Concrete
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    • v.12 no.3
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    • pp.303-318
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    • 2013
  • The purpose of this study is to present different composed material models for reinforced concrete structures (RC). For this aim a nonlinear finite element analysis program is coded in MATLAB. This program contains several yield criteria and stress-strain relationships for compression and tension behavior of concrete. In this study, the well-known criteria, Drucker-Prager, von Mises, Mohr Coulomb, Tresca, and two new criteria, Hsieh-Ting-Chen and Bresler-Pister, are taken into account. It is concluded that the coded program, the new yield criteria, and the models considered can be effectively used in the nonlinear analysis of reinforced concrete beams.

A novel meso-mechanical model for concrete fracture

  • Ince, R.
    • Structural Engineering and Mechanics
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    • v.18 no.1
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    • pp.91-112
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    • 2004
  • Concrete is a composite material and at meso-level, may be assumed to be composed of three phases: aggregate, mortar-matrix and aggregate-matrix interface. It is postulated herein that although non-linear material parameters are generally used to model this composite structure by finite element method, linear elastic fracture mechanics principles can be used for modelling at the meso level, if the properties of all three phases are known. For this reason, a novel meso-mechanical approach for concrete fracture which uses the composite material model with distributed-phase for elastic properties of phases and considers the size effect according to linear elastic fracture mechanics for strength properties of phases is presented in this paper. Consequently, the developed model needs two parameters such as compressive strength and maximum grain size of concrete. The model is applied to three most popular fracture mechanics approaches for concrete namely the two-parameter model, the effective crack model and the size effect model. It is concluded that the developed model well agrees with considered approaches.

Modified Gurson Model to Describe Non-linear Compressive Behaviour of Polyurethane Foam with Considering Density Effect (폴리우레탄 폼의 비선형 압축거동을 모사하기 위한 밀도 영향이 고려된 수정 Gurson 모델의 제안)

  • Lee, Jeong-Ho;Park, Seong-Bo;Kim, Seul-Kee;Bang, Chang-Seon;Lee, Jae-Myung
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.28 no.5
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    • pp.543-551
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    • 2015
  • Polyurethane Foam(PUF), a outstanding thermal insulation material, is used for various structures as being composed with other materials. These days, PUF composed with glass fiber, Reinforced PUF(R-PUF), is used for a insulation system of LNG Carrier and performs function of not only the thermal insulation but also a structural member for compressive loads like a sloshing load. As PUF is a porous material made by mixing and foaming, mechanical properties depend on volume fraction of voids which is a dominant parameter on density. Thus, In this study, density is considered as the effect parameter on mechanical properties of Polyurethane Foam, and mechanical behavior for compression of the material is described by using modified Gurson damage model.

Water quality management of Jeiu Harbor using material cycle model(I) - The Variation of Physical Oceanographic Environments in Jeiu Harbor - (물질순환모델을 이용한 제주항의 수질관리(I) - 제주항의 물리해양환경의 변화 -)

  • 조은일;이병걸;오윤근
    • Journal of Environmental Science International
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    • v.11 no.1
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    • pp.25-32
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    • 2002
  • In order to control of water quality in Jeju harbor, variation of physical oceanographic environments was estimated using material cycle model. It is composed of the three-dimensional hydrodynamic model for the simulation at water flow and material cycle model for the simulation of water quality. The three dimensional hydrodynamic model simulation of the circulation and mixing in Jeju Harbor has been conducted forced by Sanzi River Discharge, Tidal elevation, wind and Solar heat in case of August and November, 2000 and February and May, 2001, respectively. The results of numerical model and observation show that the model can produce realistic results of current in the harbor. The monthly variation of velocity pattern are not so much changed are found In Jeju Harbor. The residual current was forced by temperature, salinity, density, wind and tidal current. The residual current of August, 2000 are the strongest among four month. It can be explained that the density effect can be important role in residual current at Jeju Harbor. As the results of salinity distribution simulation, very low concentration of all levels were simulated in August, 2000. The flowrate of Sanzi river was investigated 77,760 ㎥ /d in August, 2000. Therefore, pollutant loadings from Sanzi river should be considered for water quality management in Jeiu harbor.

Analysis of Drying Characteristics in the Dryer Using the Refraction of Radiation (굴절 현상을 이용한 건조기에서 건조특성 해석)

  • Lee, Kong-Hoon;Choi, Byung-Il;Hong, Yong-Ju
    • Proceedings of the SAREK Conference
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    • 2006.06a
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    • pp.1191-1196
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    • 2006
  • Analysis of drying characteristics has been carried out with one-dimensional model in the dryer using the principle of the refraction of radiation. The dryer is composed of hot water tank, a plastic film conveyer belt, drying material, etc. The model considers the conduction and radiation within the plastic film and drying material. The film is semitransparent to radiation and the drying material is assumed to be semitransparent or opaque to radiation. The results shows that the effect of radiative transfer on the drying rate is relatively large when the thickness of drying material is small and the water temperature is high. When the material is thin, the drying rate by only conduction is also enhanced so that drying time can considerably be reduced.

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The Near-field Behavior of Effluent discharged from Confined Disposal Facility (제한투기시설에서 배출되는 여수의 근역거동)

  • 정대득;이중우
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • 2000.11a
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    • pp.95-107
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    • 2000
  • The primary purpose of dredging work is to maintain navigational readiness and to increase environmental amenity, so that the dredging project which is composed of excavating, removing, transporting, storing and disposing dredged material must be carefully managed to insure that dredging works are completed in a cost-effective and environmentally safe manner. The most important point in dumping operations is an estimating and reducing the impacts of discharges at the dumping area. One of the most effective method for the reduction of ecological impacts at dumping area is using the schematic process composed of the sophisticated plan, precise work and predicting/reducing the impacts based on the numerical model and field observation. In this study, the numerical model is used to predict the near-field spatial fate and begavior of effluent discharged from Confined Dumping Facility(CDF) located near coastal area. To to this purpose, reappearing of tidal current was preceded. The model is then applied to Mokpo harbor, where capital dredging and maintenance dredging are conducted simultaneously and the CDF is under construction;. In the series of model case study, we found that the near-field behavior of effluent discharged from CDF was governed by the receiving water condition, outfall geometry, characteristics of efflent and CDF operating conditions.

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