• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.10 s.181
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• pp.2461-2468
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• 2000

In this paper, single fiber pull-out test is used to measure the interfacial bonding shear strength of $Ti_{50}-Ni_{50}$ shape memory alloy composite with temperature. Fiber and matrix of $Ti_{50}-Ni_{50}$ shape memory alloy composite are respectively $Ti_{50}-Ni_{50}$ shape memory alloy and epoxy resin. To strengthen the interfacial bonding shear stress, various surface treatments are used. They are the hand-sanded surface treatment, the acid etched surface treatment and the silane coupled surface treatment etc.. The interfacial bonding shear strength of surface treated shape memory alloy fiber is greater than that of surface untreated shape memory alloy fiber by from 10% to 16%. It is assured that the hand-sanded surface treatment and the acid etched surface treatment are the best way to strengthen the interfacial bonding shear strength of $Ti_{50}-Ni_{50}$ shape memory composite. The best treatment condition of surface is 10% HNO$_3$ solution in the etching method to strengthen the interfacial bonding shear strength of $Ti_{50}-Ni_{50}$ shape memory alloy composite.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.10 s.241
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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.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.22 no.3
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• pp.624-634
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• 1998

The photoelastic model material with shape memory effect and the molding processes for the material are developed in this research. The matrix and fiber of the photoelastic model material developed in this research are epoxy resin (Araldite to hardner 10 to 3 (weight ratio)) and wire of $Ti_50-Ni_50$ shape memory alloy, respectively. It is called Ti50-Ni50 Shape Memory Alloy Fiber Epoxy Composite $(Ti_50-Ni_50SMA-FEC).$ Ti50-Ni50 SMA-FEC is satisfied with the requirements of the photoelastic model material and can be used as a photoelastic model material. The maximum recovering strain of $Ti_50-Ni_50$SMA-FEC is occurred at $80^{\circ}C$ in any prestrain of $Ti_50-Ni_50$ shape memory alloy fiber and in any fiber volume ratio. Recovering strain(force) is increased with the increment of the prestrain and the fiber volume ratio. The best prestrain of $Ti_50-Ni_50$SMA-FEC is 5% for the recovering force among 1%, 3%, 5%.

• Transactions of Materials Processing
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• v.18 no.1
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• pp.45-51
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• 2009

Shape memory alloy has been used to improve the tensile strength of composite by the occurrence of compressive residual stress in matrix using its shape memory effect. In order to fabricate shape memory alloy composite, TiNi alloy fiber and Al2024 sheets were used as reinforcing material and matrix, respectively. In this study, TiNi/Al2024 shape memory alloy composite was made by using hot press method. In order to investigate bonding condition between TiNi reinforcement and Al matrix, the micro-structure of interface was observed by using optical microscope and diffusion layer of interface was measured by using Electron Probe Micro Analyser. And the mechanical properties of composite with three parameters(volume fraction of fiber, cold rolling amount and test temperature) were obtained by tensile test. The most optimum bonding condition for fabrication the TiNi/Al2024 composite material was obtained as holding for 30min. under the pressure of 60MPa at 793K. The strength of composite material increased considerably with the volume fraction of fiber up to 7.0%. And the tensile strength of this composite increased with the reduction ratio and it also depends on the volume fraction of fiber.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.465-469
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• 1997

In this paper, shape memory compsites are made by powder metallurgy. And then, an self-strengthening effect of the composites by shape memory effect above inverse transformation temperature A/sab f/ of TiNi alloy discussed. Moreover, TiNiCo/Al composite is made by using TiNiCo alloy as fiber. And it is discused aboutaffection of Co in the shape memory composite. The results of the intelligent properties of TiNi/Ai-radical shape memory composite, using SMA, by powder metallurgy are the tensile strength of TiNiCo wire is much higher than that of TiNi wire. and the strength of TiNiCo/Al composite is generally higher than that TiNi/Al composite.

• Journal of the Korean Society for Nondestructive Testing
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• v.22 no.1
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• pp.45-52
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• 2002

It has been known that tensile residual stresses occurring by the thermal expansion coefficient mismatch between fiber and matrix is a cause of the weak strength of metal matrix composites(MMCs). In order to solve this problem, TiNi alloy fiber was used as a reinforced material in TiNi/A16001 shape memory alloy composite in this study. TiNi alloy fiber improves the tensile strength of the composite by causing compressive residual stress in matrix on the basis of its shape memory effect. Pre-strain was imposed to generate the compressive residual stresses inside the TiNi/A16001 shape memory alloy composites. AE technique was used to quantify the microscopic damage behavior of the composite at high temperature. The effect of applied pre-strains on the AE behavior was also evaluated.

• Proceedings of the KSME Conference
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• 2001.11a
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• pp.186-191
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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 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 matrix using shape memory effect of it. Pre-strain was added to generate compressive residual stress inside TiNi/A16061 shape memory alloy(SMA) composite. It was also evaluated the effect of compressive residual stress corresponding to pre-strains variation and volume fraction of TiNi alloy. AE technique was used to clarify the microscopic damage behavior at high temperature and the effect of pre-strain difference of TiNi/A16061 SMA composite. In addition, two dimensional AE source location technique was applied to inspect the crack initiation and propagation in composite.

• Proceedings of the KSME Conference
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• 2001.06a
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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.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.8 s.227
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• pp.1099-1108
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• 2004

In this paper, a study on the development of expert system for Al matrix composite with shape memory alloy fiber is performed to evaluate termomechanical behavior and mechanical properties. Expert system is very useful computer-based analysis system designed to make analysis technique and knowledge conveniently available to a lot of fabricable condition. In the developed system, it is possible to predict termomechanical behavior and mechanical properties for other composite with shape memory alloy fiber. The smartness of the shape memory alloy 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. For finite element analysis, an analytical model is assumed two dimensional axisymmetric model compared of one fiber and the matrix. To evaluate the strength of composite using FEM, the concept of smart composite was simulated on computer Thus, in this paper, the FEA was carried out at two critical temperature conditions; room temperature and high temperature(363k). The finite element analysis result was compared with the test result for the analysis validity.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.687-691
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• 2001

Al alloy matrix composite with TiNi shape memory fiber as reinforcement has been fabricated by hot pressing to investigate mechanical properties. The stress-strain behavior of the composites was evaluated at temperatures between 363K and room temperature as a function of pre-strain by using experimental and finite element analysis, and both cases showed that the tensile stress at 363K was higher than that of the room temperature. Especially, the tensile stress of this composite increases with increasing the amount of pre-strain, and it also depends on the volume fraction of fiber and heat treatment. The smartness of the composite 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 pre-strained.