• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.1097-1100
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• 2001

In this paper, the electro-chemical-machining characteristics of Ni-Ti Shape Memory Alloy(SMA) was investigated. From the experimental results, the optimal electro chemical machining conditions for satisfying the machining quality(fine surface & high recovery stress) might be confirmed. And it was concluded that optical electro chemical condition for Ni-Ti SMA could be obtained at approximately 100% current efficiency and high frequency pulse current.

• 한국안전학회지
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• 제29권4호
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• pp.28-33
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• 2014

Recently, the actuator worked by the driving recovery-force of the thermo elastic martensitic transformation of shape memory alloys(SMA) has been studied. This paper presents a study on the fatigue life of shape memory alloy (SMA) actuators undergoing thermally induced martensitic phase transformation under various stress levels. shape memory recoverable stress and strain of Ti-44.5at.%Ni-8at.%Cu alloys were by means of constant temperature tensile tests. Differential scanning calorimetry (DSC) was employed in order to investigate the transformation characteristics of the alloy before the tests. the results were summarized as follows. The martensite inducing stress incerased with the increasing of the Cu-contents. The fatigue life decreased with the increasing of the test load and the Cu-content. The data acquired will be very useful during the design process of an SMA NiTiCu element as a functional part of an actuator.

• Earthquakes and Structures
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• 제23권5호
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• pp.431-444
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• 2022

The unique thermomechanical properties of shape memory alloys (SMAs) make it a versatile material for strengthening and repairing structures. In particular, several research studies have already demonstrated the effectiveness of using the heat activated shape memory effect of nickel-titanium (Ni-Ti) based SMAs to actively confine concrete members. Despite the proven effectiveness and wide commercial availability of Ni-Ti SMAs, however, their high cost remains a major obstacle for applications in real structural engineering projects. In this study, the shape memory effect of a new, much more economical iron-based SMA (Fe-SMA) is characterized and the compressive behavior of concrete confined with Fe-SMA strips is investigated. Tests showed the Fe-SMA strips used in this study are capable of developing high levels of recovery stress and can be easily formed into hoops to provide effective active and passive confining pressure to concrete members. Compared to concrete cylinders confined with conventional carbon fiber-reinforced polymer (CFRP) composites, Fe-SMA confinement yielded significantly higher compressive deformation capacity and residual strength. Overall, the compressive behavior of Fe-SMA confined concrete was comparable to that of Ni-Ti SMA confined concrete. This study clearly shows the potential for Fe-SMA as a robust and cost-effective strengthening solution for concrete structures and opens possibilities for more practical applications.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.723-726
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• 2002

In the recent years, as the research and the development of micro and precision machinery become active, the interest of micro actuators using SMA(Shape Memory Alloy) has been increased. The dynamic characteristic analysis of SMA is necessary for actuator application and many common researches report the material characteristics of SMA sufficiently. However, the research of dynamic characteristics is very deficient. In this paper, the helical spring is fabricated with NiTi SMA wire of high resistivity The farce, response speed, temperature, and displacement are measured by digital force gauge, infrared thermometer, and laser displacement sensor so that the dynamic characteristics of this SMA actuator is analyzed.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.210-215
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• 2008

This paper presents an experimental study on a bending actuator with a shape memory alloy wire. In this study, we introduced design process and experimental result of the bending actuator. The bending actuator consists of a SMA wire, springs, and a glass/epoxy strip. In the bending actuator, springs were used to restore the SMA wire to its initial shape right after actuation. To obtain properties of the SMA wire, DSC test was performed and the behavior of the SMA wire under different loadings was observed. Finally, the proposed bending actuator shows reasonable actuation behavior with relatively lower power consumption, fast response and effective efficiency.

• 한국정밀공학회지
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• 제13권9호
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• pp.54-61
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• 1996

Because of its high energy density, the use of shape memory alloys(SMA) in designing microactuatiors is gaining much attention in recent years. Shape memory alloys can undergo a shape change at a low temperature with a small applied deformation force, and retain this deformation until they are heated, at which point they return to the original shape. This is called the shape memory effect(SME), and a plethora of alloys show this effect. Among them, TiNi-based alloys have relatively high electrical resistivity, which to develope helical-shape memory springs. These springs are used to develop fast protatonist/antagonist configuration actuators. The developed actuator has an actuation speed of 1 mm per 15 .approx. 20 ms and a minimum operating period of 2 sec.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2003년도 추계학술대회
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• pp.47-52
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• 2003

In the recent years, as the research and the development of micro and precision machinery become active, the interest of micro actuators using SMA(Shape Memory Alloy) has been increased. The dynamic characteristic analysis of SMA is necessary for actuator application and many common researches report the material characteristics of SMA sufficiently. However, the research on dynamic characteristics is very deficient. In this paper, the helical spring are fabricated with NiTi SMA wire of high resistivity. The force, response speed, temperature, and displacement are measured by digital force gauge, infrared thermometer, and laser displacement sensor so that the dynamic characteristics of this SMA is analyzed. Also, bidirectional actuator was fabricated and experimented fir its performance.

• Structural Engineering and Mechanics
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• 제22권2호
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• pp.241-262
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• 2006

NiTi-wire shape memory alloy (SMA) dampers, that utilize NiTi SMA wires to simultaneously damp tension, compression and torsion, was developed for structural control implementation in this study. First, eight reduced-scale NiTi-wire SMA dampers were constructed. Then tension, compression and torsion experiments using the eight reduced-scale NiTi-wire SMA dampers of different specification were done. The experimental results revealed all of the eight reduced-scale NiTi-wire SMA dampers had the ability to simultaneously supply tension-compression damping and torsion damping. Finally, mechanics analysis of the NiTi-wire SMA dampers was done based on a model of the SMA-wire restoring force and on tension-compression and torsion damping analysis. The damping analytical results were found to be similar to the damping experimental results.

• 한국기계가공학회지
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• 제10권5호
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• pp.51-57
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• 2011

The lightweight and compact actuator with high power is required to perform motion with multiple degrees of freedom. To reduce the size and inertia of a robot manipulator, the mechanical transmission system is used. The shape memory alloy(SMA) is similar to the muscle-tendon-bone network of a human hand. However, there are some drawback and nonlinearity, such as the hysteresis and the stress dependence. In this paper, the design of the underactuated robot hand is studied. The 3-finger dexterous hand is driven by the SMA actuator using segmental mechanism. This digital approach enables to overcome the nonlinearity of SMA wire. The translational displacement of SMA actuator required to bend a phalanx of the underactuated robot hand is estimated and the bending angle of the underactuated robot hand according to input displacement of SMA actuator is predicted by the multi-body dynamic analysis.

• Smart Structures and Systems
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• 제14권4호
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• pp.643-658
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• 2014

This paper presents the design, modelling and, simulation and experimental results of a shape memory alloy (SMA) actuator based critical motion control application. Dynamic performance of SMA and its ability in replacing servo motor is studied for which the famous open loop unstable balancing ball and beam system direct driven by antagonistic SMA is designed and developed. Simulation uses the mathematical model of ball and beam structure derived from the first principles and model estimated for the SMA actuator by system identification. A PID based cascade control system consisting of two loops is designed and control of ball trajectory for various target positions with settling time as control parameter is verified experimentally. The results demonstrate the performance of SMA for a complicated i.e., under actuated, highly nonlinear unstable system, and thereby it's dynamic behaviour. Control strategies bring out the effectiveness of the actuator and its possible application to much more complex applications such as in aerospace control and robotics.