• Title, Summary, Keyword: 예변형률

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Evaluation on Mechanical Properties of a Smart Composite Using the finite Element Method and the Acoustic Emission Technique (FEM과 AE를 이용한 지적복합재료의 기계적특성 평가)

  • Park, Young-Chul;Lee, Jin-Kyung
    • Journal of the Korean Society for Nondestructive Testing
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    • v.24 no.3
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    • pp.233-239
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    • 2004
  • Smart material is used in various applications such as for glass frame, for medical instruments and for a part of sensors. Smart composite materials ran be applied to a part of aircraft and to the on-line monitoring system for industrial structures, using the shape memory effect. However, it is very difficult to simulate and analyze the shape memory effect in smart composites. In this paper, a two dimensional axisymmetric model was proposed to analyze the smart composite of one fiber and matrix using the finite element method(FEM). The finite element analysis was carried out in two renditions of the room temperature(293K) and a higher temperature (363K). The results we.e compared with the experimental results to confirm the validity of the analysis. In addition, the acoustic emission(AE) technique was used to study the microscopic damage behavior and the effect of pre-strains on TiNi/A16061 shape memory alloy composite.

Development of Strength Analysis Modules for TiNi/Al 6061 Shape Memory Alloy (TiNi/Al 6061 형상기억 복합재료의 강도해석 모듈 개발)

  • 이동화;박영철;박동성;이규창
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.692-696
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    • 2001
  • Thermo-mechanical behavior and mechanical properties of intelligent polymer matrix composite with SMA fiber are experimentally studied. It is found that increments of compressive thermal strain is observed as the pre-strain and TiNi volume fraction increase. The smartness of the SMA is given due to the shape memory effect of the TiNi fiber which generates compressive residual stress in the matrix material when heated after being prestrained. In the paper, alloy is based on the general purpose commercial code ANSYS. And for the purpose of easy and fast user's analysis, it is developed the Graphical User Interface by using Tcl/Tk language.

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Fracture Characteristic of TiNi/A16061 Share Memory Alloy Composite using Acoustic Emission Technique (AE 기법을 이용한 TiNi/A16061 형상기억복합재료의 파괴특성평가)

  • Lee, Jin-Kyung;Park, Young-Chul;Ku, Hoo-Taek;Park, Dong-Sung;Lee, Kyu-Chang
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.26 no.2
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    • pp.275-282
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    • 2002
  • Tensile residual stress happen by difference of coefficients of thermal expansion between fiber and matrix is one of the serious problems in metal matrix composite(MMC). In this study, TiNi fiber was used to solve the tensile residual stress as the reinforced material. TiNi fiber improves the tensile strength of composite by occurring compressive residual stress in matrix using shape memory effect of it. Pre-strain was added to generate compressive residual stress inside TiNi/A16061 composite. It was also evaluated the effect of compressive residual stress corresponding to pre-strains variation. AE technique was used to clarify the microscopic damage behavior at high temperature and the effect of pre-strain difference of TiNi/A16061 shape memory alloy composite.

Fracture Characteristic of TiNi/A16061 Share Memory Alloy Composite at High Temperature using Acoustic Emission Technique (AE 기법을 이용한 TiNi/A16061 형상기억복합재료의 고온파괴특성평가)

  • Lee, Jin-Kyung;Park, Young-Choul;Kang, Dong-Hyun;Park, Dong-Sung;Lee, Kyu-Chang
    • Proceedings of the KSME Conference
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    • pp.72-77
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    • 2001
  • Tensile residual stress happen by difference of coefficients of thermal expansion between fiber and matrix is one of the serious problems in metal matrix composite(MMC). In this study, TiNi fiber was used to solve the tensile residual stress as the reinforced material. TiNi fiber improves the tensile strength of composite by occurring compressive residual stress in matrix using shape memory effect of it. Pre-strain was added to generate compressive residual stress inside TiNi/A16061 composite. It was also evaluated the effect of compressive residual stress corresponding to pre-strains variation. AE technique was used to clarify the microscopic damage behavior at high temperature and the effect of pre-strain difference of TiNi/A16061 shape memory alloy composite.

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The Strength Evaluation of TiNi/A16061 Composite by Using Finite Element Method (유한요소법을 이용한 TiNi/A16061 형상기억 복합재료의 강도평가)

  • Park, Yeong-Cheol;Lee, Gyu-Chang;Park, Dong-Seong;Lee, Dong-Hwa;Dong Hwa
    • Journal of the Korean Society for Precision Engineering
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    • v.19 no.2
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    • pp.72-78
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    • 2002
  • Thermomechanical behavior and mechanical properties of A16061 matrix composite with shape memory alloy(SMA) fiber are studied by using fnite element analysis(FEA). The smartness of the SMA is given due to the shape memory effect of the TiNi fiber which generates compressive residual stress in the matrix material when healed after being prestrained. In this paper, an analytical model is assumed two dimentional axisymetric model of one fiber and around the matrix. To evaluate the strength of composite usig FEM, the concept of smart composite was simulated on computer. The Shape memory effect(SME) simulation is very difficult using FEM because of the nonlinear analysis and the elastic plastic analysis. Thus, in this paper, the FEA was carried out at two critical temperature conditions; room temperature and high temperature(363K). The analysis is compare the finite element analysis result with the test result for the analysis validity.

A Study on the Microscopic Damage Behavior and the Damage Position Evaluation of TiNi/Al6061 Share Memory Alloy Composite (TiNi/A16061 형상기억복합재료의 미시적 손상거동과 손상위치측정에 관한 연구)

  • Lee, Jin-Gyeong;Park, Yeong-Cheol;Gu, Hu-Taek;Lee, Gyu-Chang
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.26 no.9
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    • pp.1787-1794
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    • 2002
  • TiNi alloy fiber was used to solve the problem of the tensile residual stress as the reinforced material. TiNi alloy fiber improves the tensile strength of composite by occurring compressive residual stress in the matrix using shape memory effect. In order to generate compressive residual stress in TiNi/Al6061 shape memory alloy(SMA) composite, 1, 3 and 5% pre-strains were applied to the composite in advance. It was also evaluated the effect of compressive residual stress corresponding to the pre-strain variation and the volume fraction of TiNi alloy. AE technique was used to clarify the microscopic damage behavior at high temperature and the effect of pre-strain in TiNi/Al6061 SMA composite. The results of the microscopic damage evaluation of TiNi/Al6061 SMA composite under various pre-strain using AE technique can be divided into three stage corresponding to the AE signals. AE counts and events were useful parameters to evaluate the fracture mechanism according to the variation of pre-strain. In addition, two dimensional AE source location technique was applied for monitoring the crack initiation and propagation in composite.

Effect of Cold Rolling on Fatigue Crack Propagation of TiNi/A16061 Shape Memory Composite (TiNi/A16061 형상기억복합재료의 피로균열진전에 대한 냉간압연효과)

  • Lee Jin-Kyung;Park Young-Chul;Lee Kyu-Chang;Lee Sang-Pill;Cho Youn-Ho;Lee Joon-Hyun
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.29 no.10
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    • pp.1315-1320
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    • 2005
  • TiNi alloy fiber was used to recover the original shape of materials using its shape memory effect. The shape memory alloy plays an important role within the metal matrix composite. The shape memory alloy can control the crack propagation in metal matrix composite, and improve the tensile strength of the composite. In this study, TiNi/A16061 shape memory alloy(SMA) composite was fabricated by hot press method, and pressed by a roller for its strength improvement. The four kinds of specimens were fabricated with $0\%,\;3.2\%,\;5.2\%\;and\;7\%$ and volume fraction of TiNi alloy fiber, respectively. A fatigue test has performed to evaluate the crack initiation and propagation for the TiNi/A16061 SMA composite fabricated by かis method. In order to study the shape memory effect of the TiNi alloy fiber, the test has also done under both conditions of the room temperature and high temperature. The relationship between the crack growth rate and the stress intensity factor was clarified for the composite, and the cold rolling effect was also studied.