• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.3
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• pp.405-413
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• 1997

In the present paper, it is attempted to reconfirm the "Intelligent" material properties using both the sintered TiNi/Al(1100) matrix composite made by powder metallurgy method and the squeeze-casted TiNi/Al6061 specimens. A metal matrix composite is, its fault has been considered to deteriorate a strength of composite by heating residual stress of the matrix. Therefore, it is necessary to remove a tensile residual stress, to produce the strength of a composite better. On the contrary, if compressive residual stress happens in matrix of composite in place of tensile residual stress, it will make the strength of composite better. So that, this paper introduce the development of a high strength of composite, by using compressive residual stress well, on the study. By using these specimens, shape memory strengthening effects in tensile strength and fatigue crack propagation above inverse transformation temperature of TiNi fiber were investigated. We occurs the prestrain and volume fraction for to discuss the effects of a composite strength. Moreover, by SEM observation, the effect of the residual stress at the interface between Al matrix and TiNi fiber and some brittle precipitation layers such as inter metallic compounds on fracture mechanisms was discussed metallurgically.urgically.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.1
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• pp.9-15
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• 2011

The influence of the strain-rate on the superelastic behaviors of shape memory alloys (SMAs) wires is experimentally and numerically investigated. The one-dimensional SMA constitutive equations considering strain-rate effect is developed. The evolution of stress-strain curves of SMA wires is examined with various strain-rates. Results show that the superelastic behaviors of SMAs may significantly be changed depending on the variation of strain-rate.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1232-1235
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• 2005

In recent years, as the robot technology is developed the researches on the artificial muscle actuator that enable robot to move dextrously like biological organ become active. The widely used materials for artificial muscle are the shape memory alloy and the electroactive polymer. These actuators have the higher energy density than the electromechanical actuator such as motor. However, there are some drawbacks for actuator. SMA has the hysterical dynamic characteristics. In this paper the segmented binary control for reducing the hysteresis of SMA is proposed and the simulation of anthropomorphic robotic hand is performed using ADAMS.

• International Journal of Aeronautical and Space Sciences
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• v.8 no.2
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• pp.76-81
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• 2007

The fiber reinforced laminated composite structures are very susceptible to be damaged when they are impacted by foreign objects. To increase the impact resistance of the laminated composite structures, shape memory alloy(SMA) thin film is embedded in the structure. For the numerical impact analysis of SMA hybrid composite structures, SMA modeling tool is developed to consider pseudoelastic effect of SMAs. Moreover, the damage analysis is considered using failure criteria and a simple damage model for reasonable impact analysis. The numerical results are verified with the experimental ones. Impact analyses for composite plate with pre-strained SMAs are numerically performed and the damage areas are investigated.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.5 s.176
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• pp.1352-1361
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• 2000

We obtain a micromechanics-based Helmholtz free energy and then in the framework of irreversible thermodynamics, a kinetic relation, a martensitic nucleation criterion and the reorientation criterion of martensitic variants are obtained. These relations are valid for a three-dimensional proportional and non-proportional loadings and for a combination of mechanical and thermal loading. From the simulated pseudoelastic stress-strain relation of a single crystal with loading rate effect, polycrystalline behavior in case of proportional and non-proportional loading is predicted by a homogenization method. The obtained results are compared quantitatively with experimental results.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2003.04a
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• pp.10-13
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• 2003

The dynamic analysis of composite plate with embedded shape memory alloys (SMAs) is studied using the finite element method. Active frequency tuning of a composite plate under electrical heating of SMAs is analyzed. The actuation of SMAs is modeled by Brinson's one-dimensional constitutive equation. The influences of the boundary conditions, the ply orientations and the pre-strains of SMA wires on the thermo-dynamic response of composite plate are discussed. It is found that the effect of SMAs on the dynamic response of composite plate is significant.

• Journal of the Korean Society for Heat Treatment
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• v.6 no.4
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• pp.213-222
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• 1993

This research was performed to investigate the transformation behavior and shape memory effect of Cu-13.5Al-4.5Ni(wt%) alloy with various aging temperature and time. The results obtained in this study are as follows: Transformation temperature was very increased when aging temperature is at $250^{\circ}C$. The variation of transformation temperature in first reverse transformation cycle and second was very significant, but there was little difference in case of 2nd and 3rd. Transformation temperature at various aging temperature was increased with increasing of aging temperature and time. Microvickers hardness was increased with increasing of aging temperature and time. It was found that ${\alpha}$ and ${\gamma}_2$ phase were created by aging of long time at high temperature.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2005.05a
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• pp.144-149
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• 2005

In recent years, as the robot technology is developed the researches on the artificial muscle actuator that enable robot to move dextrously like biological organ become active. The widely used materials for artificial muscle are the shape memory alloy and the electroactive polymer. These actuators have the higher energy density than the electromechanical actuator such as motor. However, there are some drawbacks for actuator. SMA has the hysterical dynamic characteristics. In this paper the segmented binary control for reducing the hysteresis of SMA is proposed and the simulation of anthropomorphic robotic hand is performed using ADAMS.

• Bulletin of the Korean Chemical Society
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• v.33 no.2
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• pp.692-694
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• 2012

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.1
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• pp.130-137
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• 2019

Precast concrete (PC) structure is one of the type of the structures which is made in a facility prior to installing it to a construction field. The contact surfaces between two PC structures should be treated for obtaining enough binding force by inducing prestressing force. However, in the many cases, the contact surface causes the crack and leakage of water. These cracks and water leakage can cause the corrosion of the rebar, and the corrosion of the rebar can severely reduce the long-term durability. In this study, the SMA wire connector is suggested to solve the problem with the contact surfaces between two PC structures. The pull-out resistance of the suggested SMA wire connector is evaluated by conducting the tests to find the effect of the number of wires, shape of connector part, and shape memory effect. As a result of this study, the empirical formula is suggested to estimate the pull-out resistance related with the effects of the shape of the connector, shape memory effect, and the adhesive force. The validity between the estimated pull-out resistance and the measured value is confirmed.