• Title, Summary, Keyword: 재료 물성치

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Stiffness Prediction of Spatially Reinforced Composites (공간적으로 보강된 복합재료의 강성예측)

  • 유재석;장영순;이상의;김천곤
    • Composites Research
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    • v.17 no.5
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    • pp.25-38
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    • 2004
  • In this study, the stiffness of spatially reinforced composites (SRC) are predicted by using superposition of a rod and matrix stiffnesses in an arbitrary direction. To confirm the predicted values, the material properties of SRC are measured. The predicted values from the volume average of stiffness matrix are consistent with the tested values in a rod direction, but are inconsistent in an off-rod direction while reverse is true fur the volume average of compliance matrix. Therefore, the harmony function from superposition of stiffness and compliance matrix is introduced. The predicted values from the harmony function are consistent with the tested values in both the rod and the off-rod directions.

Study on material properties of composite materials using finite element method (유한요소법을 이용한 복합재의 물성치 도출에 대한 연구)

  • Kim, Seong-Uk;Jeong, Cheol-Gyun
    • Proceeding of EDISON Challenge
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    • pp.229-233
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    • 2015
  • 복합재는 높은 비강도와 비강성을 가지고 있어 자동차, 항공기 등 전반적인 산업분야에서 널리 사용되는 재료이다. 우주선의 노즐 부분과 같이 높은 온도뿐만 아니라 높은 압력이 작용하는 환경에서 사용하기 위한 재료로 복합재가 필요하다. 복합재의 물성치를 아는 것은 매우 중요한데 모재(matrix)와 강화섬유(fiber) 각각의 물성치를 수치적으로 대입해 얻는 결과는 실험값과의 오차가 커 예측하는데 있어 더 정확한 방법이 필요할 것이다. 본 연구에서는 유한요소법을 이용한 EDISON용 CASADsolver 프로그램을 활용해 분석하였다. Matrix와 fiber의 물성치를 대입해 복합재의 물성치를 구해 실험으로 측정된 물성치, 경험식으로 계산된 물성치와 비교를 하였다.

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Crimp Angle Dependence of Effective Properties for 3-D Weave Composite (굴곡각에 따른 3차원 평직 복합재료의 등가 물성치 예측)

  • Choi, Yun-Sun;Woo, Kyeongsik
    • Composites Research
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    • v.29 no.1
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    • pp.33-39
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    • 2016
  • In this study, geometric modeling and finite element analysis of 3-dimensional plain weave composite unit cell consisting of 3 interlaced fiber tows and resin pocket were performed to predict effective properties. First, tow properties were obtained from micro-mechanics finite element unit cell analysis, which were then used in the meso-mechanics analysis. The effective properties were obtained from a series of unit cell analyses simulating uniaxial tensile and shear tests. Analysis results were compared to the analysis and experimental results in the literature. Various crimp angles were considered and the effect on the effective properties was investigated. Initial failure strengths and failure sequence were also examined.

A Method of Measuring the Plastic Properties of Materials using Spherical Indentation (Spherical Indentation 실험을 이용한 재료 소성 물성치 측정방법)

  • Li, Guanghe;Kang, Yoon-Sik;Xi, Chen;Park, Tae-Hyo
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.23 no.4
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    • pp.353-360
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    • 2010
  • In this paper, an efficient algorithm is established in order to estimate the plastic properties of power-law hardening bulk specimen materials with one simple spherical indentation impression test. This work is based on a new formulation of representative strain and, therefore, compare to the preceding approaches the fitting parameters are significantly reduced. Moreover, the new definition of representative strain endowed more physical meaning to the representative strain. In order to verify the reliability of the reverse analysis, we have studied a broad set of materials whose property ranges cover essentially all engineering metals and alloys. Based on the indentation force-displacement P-${\delta}$ curves obtained from numerical simulations, the characteristics of the indentation response and material elastoplastic properties are bridged via explicit functions. Next, through the procedure of reverse analysis the yield stress and power-law hardening exponent of bulk specimen materials can be determined. Finally, good agreement between the result from reverse analysis and initial input data from experiment can be observed.

Study on Material Properties of Composite Materials using Finite Element Method (유한요소법을 이용한 복합재의 물성치 도출에 대한 연구)

  • Jung, Chul-Gyun;Kim, Sung-Uk
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.29 no.1
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    • pp.61-65
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    • 2016
  • Composites are materials that are widely used in industries such as automobile and aircraft. The composite material is required as a material for using in a high temperature environment as well as acting as a high pressure environment like the nozzle part of the ship. It is important to know the properties of composites. Result values obtained substituting the properties of matrix and fiber numerically have an large error compared with experimental value. In this study we utilize CASADsolver EDISON program for using Finite Element Method. Properties by substituting the fiber and Matrix properties of the composite material properties were compared with those measured in the experiment and calculated by the empirical properties.

Investigation on Mechanical Properties of Flax/Vinyl Ester Natural Fiber Composite (아마/비닐 에스테르 자연 섬유 복합재료의 기계적 특성 분석 연구)

  • Park, Hyunbum;Kong, Changduk;Lee, Jeonghwan;Kim, Ingwon;Lee, Hoyeon
    • Composites Research
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    • v.27 no.1
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    • pp.19-24
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    • 2014
  • In this study, an investigation on mechanical properties of flax/vinyl ester natural fiber composite was performed as a precedent study on the design of eco-friendly structure using flax/vinyl ester composite. Vacuum Assisted Resin Transfer Molding(VARTM) manufacturing method was adopted for manufacturing the flax fiber composite specimen. The mechanical properties of the manufactured flax composites were compared with flax composite data cited from some references. Based on this, the experimental data showed that the flax/vinyl ester composite has some advantages when it is applied to environment-friendly structure.

Characterization and Prediction of Elastic Constants of Twisted Yarn Composites (Twisted Yarn 복합재료의 물성치 시험 및 탄성계수 예측)

  • 변준형;이상관;엄문광;김태원;배성우
    • Composites Research
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    • v.15 no.6
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    • pp.30-37
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    • 2002
  • A stiffness model has been proposed to predict elastic constants of twisted yam composites. The model is based upon the unit cell structure, the coordinate transformation, and the volume averaging of compliance constants for constituent materials. For the correlation of analytic results with experiments, composite samples of various yam twist angles were tested, and strength and Young's modulus under tensile, compressive, and shear loading have been obtained. The sample was fabricated by the RTM process using glass yarns and epoxy resin. The correlations of elastic constants showed relatively good agreements. The model provides the predictions of the three-dimensional engineering constants, which are valuable input data for the analytic characterization of textile composites made of twisted yam.

A Review of Mean-Field Homogenization for Effective Physical Properties of Particle-Reinforced Composites (평균장 균질화를 이용한 입자 강화 복합재의 유효 물성치 예측 연구 동향)

  • Lee, Sangryun;Ryu, Seunghwa
    • Composites Research
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    • v.33 no.2
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    • pp.81-89
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    • 2020
  • In this review paper, we introduce recent research studied effective physical properties of the reinforced composite using mean-field homogenization. We address homogenization for effective stiffness and expand it to effective thermal/electrical conductivity and dielectric constant. Multiphysics problems like piezoelectricity and thermoelectricity are considered by simplifying the constitutive equation into the linear equations like Hooke's law. We present a generalized theoretical formula for predicting effective physical properties of composite and validation by against finite element analysis.

Investigation on the validity of the rule of mixtures (복합재료 혼합법칙의 타당성 검토)

  • 이창성;김승조
    • Proceedings of the Korean Society For Composite Materials Conference
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    • pp.111-117
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    • 1999
  • 섬유강화 복합재료의 섬유와 수지까지 세부적으로 모델링이 가능한 Direct Numerical Simulation을 통해서 Boron/Aluminum 섬유강화 복합재료의 탄성계수들을 구해 보았다. 수치실험에서는 복합재료를 직교이방성 물질로 가정하였고, 특정 체적에 대한 평균치를 이용해서 물성치를 구하였으며, 혼합법칙에 의해서 구한 값 및 대표체적요소(Representative Volume Element)를 사용해서 구한 값들과 비교하였다. 혼합법칙의 경우, 섬유방향 인장계수(E₁)을 제외한 나머지 물성치들에 대해서는 상당한 차이를 나타내며, 이는 혼합법칙 유도과정에서 가정한 기본가정들이 적절하지 않기 때문이라는 것을 수치실험(Numerical Experiment)을 통해 알 수 있었다.

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A Simple Method for the Estimation of Hyperelastic Material Properties by Indentation Tests (압입시험을 통하여 초탄성 재료 물성치를 평가하는 단순한 방법)

  • Song, Jae-Uk;Kim, Min-Seok;Jeong, Gu-Hun;Kim, Hyun-Gyu
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.32 no.5
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    • pp.273-278
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    • 2019
  • In this study, a new simple method for the estimation of hyperelastic material properties by indentation tests is proposed. Among hyperelastic material models, the Yeoh model with three material properties ($C_{10}$, $C_{20}$, $C_{30}$) is adopted to describe the strain energy density in terms of strain invariants. Finite element simulations of the spherical indentation of hyperelastic materials of the Yeoh model with different material properties are performed to establish a database of indentation force-displacement curves. The indentation force-displacement curves are fitted by cubic polynomials, which are approximated as a product of third-order polynomials of ($C_{10}$, $C_{20}$, $C_{30}$). A regression analysis is conducted to determine the coefficients of the equations for the indentation force-displacement curve approximations. A regression equation is used to estimate the hyperelastic material properties. The present method is verified by comparing the estimated material properties with true values.