• Proceedings of the Korean Society For Composite Materials Conference
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• 2003.10a
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• pp.146-149
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• 2003

Two-way shape memory effect(TWSME) under residual stresses are considered in the present study. The structure using two-way shape memory alloy(SMA) concept returns to its initial shape by increasing or decreasing temperature under the initially given residual stress. In the present study, we use a thermo-mechanical constitutive equation of SMA and laminated composite plates are considered as simple morphing structural components which are based on first order shear deformable laminated composite plate with large deflection. Numerical results of fully coupled SMA-composite structures are presented

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.18 no.6
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• pp.551-557
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• 2009

A development of smart materials is becoming a prominent issue on present industries. A smart material, included in functions, is needed for micro fabrication. A shape memory alloy(SMA) in a smart material is best known material. Ni-Ti alloy, composed of nikel and titanium is one of the best shape memory alloy(SMA). Nitinol SMA is used for a lot of high tech industry such as aero space, medical device, micro actuator, sensor system. However, Ni-Ti SMA is difficult to process to make a shape and fabrications as traditional machining process. Because nitinol SMA, that is contained nikel content more than titanium content, has similar physical characteristics of titanium. In this paper, the characteristics of ECM grooving process for nitinol SMA are investigated by experiments. The experiments in this study are progressed for power, gap distance and machining time. The characteristics are found each part. Fine shape in work piece can be found on conditions; current 6A, duty factor 50%, gap distance 15%, gap distance $15{\mu}m$, machining time 10min.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.10a
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• pp.75-79
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• 2001

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 for its performance.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.755-758
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• 1997

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 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 actuator is analyzed.

• Smart Structures and Systems
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• v.14 no.4
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• pp.541-558
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• 2014

This paper proposes a new design of shape memory alloy (SMA) wire actuated gripper for open mode operation. SMA can generate smooth muscle movements during actuation which make them potentially good contenders in designing grippers. The principle of the shape memory alloy gripper is to convert the linear displacement of the SMA wire actuator into the angular displacement of the gripping jaw. Steady state analysis is performed to design the wire diameter of the bias spring for a known SMA wire. The gripper is designed to open about an angle of $22.5^{\circ}$ when actuated using pulsating electric current from a constant current source. The safe operating power range of the gripper is determined and verified theoretically. Experimental evaluation for the uncontrolled gripper showed a rotation of $19.97^{\circ}$. Forced cooling techniques were employed to speed up the cooling process. The gripper is simple and robust in design (single movable jaw), easy to fabricate, low cost, and exhibits wide handling capabilities like longer object handling time and handling wide sizes of objects with minimum utilization of power since power is required only to grasp and release operations.

• Smart Structures and Systems
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• v.14 no.5
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• pp.765-784
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• 2014

In comparison with conventional shape memory actuated structures, antagonistic shape memory alloy (SMA) actuators permits a fully reversible two-way response and higher response frequency. However, excessive internal stress could adversely reduce the stroke of the actuators under repeated use. The two-way shape memory effect might further decrease the range of the recovered strain under actuation of an antagonistic SMA actuator unless additional components (e.g., spring and stopper) are added to regain the overall actuation capability. In this paper, the performance of all four possible types of SMA actuation schemes is investigated in detail with emphasis on five key properties: recovered strain, cyclic degradation, response frequency, self-sensing control accuracy, and controllable maximum output. The testing parameters are chosen based on the maximization of recovered strain. Three types of these actuators are antagonistic SMA actuators, which drive with two active SMA wires in two directions. The antagonistic SMA actuator with an additional pair of springs exhibits wider displacement range, more stable performance under reuse, and faster response, although accurate control cannot be maintained under force interference. With two additional stoppers to prevent the over stretch of the spring, the results showed that the proposed structure could achieve significant improvement on all five properties. It can be concluded that, the last type actuator scheme with additional spring and stopper provide much better applicability than the other three in most conditions. The results of the performance analysis of all four SMA actuators could provide a solid basis for the practical design of SMA actuators.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.67-71
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• 2003

A hot press method was used to create the optimal fabrication condition for a Shape Memory Alloy(SMA) composite. The bonding strength between the matrix and the reinforcement within the SMA composite by the hot press method was more increased by cold rolling. In this study, the objective was to develop an on-line monitoring system in order to prevent the crack initiation and propagation by shape memory effect in SMA composite. Shape memory effect was used to prevent the SMA composite from crack propagation. For this system an optimal AE parameter should be determined according to the degree of damage and crack initiation. When the SMA composite was heated by the plate heater attached at the composite, the propagating cracks could be controlled by the compressive force of SMA.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.12
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• pp.1153-1160
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• 2008

In this paper, the algorithm of Abaqus UMAT is introduced to analyze the shape memory alloy. The SMA has two main effects which show non-linearity. Due to this, it is hard to analyze SMA using analysis tools and to describe all of two effects. Therefore, in this study, the program using Abaqus UMAT based on Modified Brinson model is used to analyze SMA. The martensite fraction, the most important factor which defines SMA motion, is also calculated by Fortran program in UMAT. In addition, the tensile test of SMA specimen is conducted. The availability of algorithm is proved by comparing analysis to experimental result.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.4
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• pp.515-523
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• 2003

Shape memory is physical phenomenon which a platically metal is restored to its original shape by a solid state phase change by heating. TiNi alloy the most effective material in the shape memory alloy(SMA). To study(measure) recovery stress of intelligent composite. Ti50-Ni50 shape memory matrix with prestrain SMA fiber. When SMA fiber of the intelligent composite is heated over austenite starting temperature(As) by electric heating. a recovery stress are generated. The recovery stress of the intelligent composite was measured by strain gage or photoelastic experiment. Measuring method of recovery stress by photoelastic experiment was developed in this research. It was certified that photoelastic experiment was more effective and more precise than strain gage method in the measurement of recovery stress.

• Earthquakes and Structures
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• v.23 no.2
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• pp.207-219
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• 2022

Seismic response control has always been a grave concern with the damage and collapse of many buildings during the past earthquakes. While there are several existing techniques like base isolation, viscous damper, moment-resisting beam-column connections, tuned mass damper, etc., many of these are succumbing to either of large displacement, near-fault, and long-period earthquakes. Keeping this viewpoint, extensive research on the application of smart materials for seismic response control of buildings was attempted during the last decade. Shape Memory Alloy (SMA) with its unique properties of superelasticity and shape memory effect is one of the smart materials used for seismic control of buildings. In this paper, an exhaustive review has been compiled on the seismic control applications of SMA in buildings. Unique properties of SMA are discussed in detail and different phases of SMA along with crystal characteristics are illustrated. Consequently, various seismic control applications of SMA are discussed in terms of performance and compared with prevalent base isolators, bracings, beam-column connections, and tuned mass damper systems.