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Instruments and methods for measuring a property of a shape memory alloy are provided. The instrument includes a base plate, a non-contact movable mass, a force gauge, an actuator, a biasing spring, a heater for heating the shape memory alloy, and a non-contact displacement detector. The biasing spr

Instruments and methods for measuring a property of a shape memory alloy are provided. The instrument includes a base plate, a non-contact movable mass, a force gauge, an actuator, a biasing spring, a heater for heating the shape memory alloy, and a non-contact displacement detector. The biasing spring and the shape memory alloy are disposed whereby a force applied thereby is applied substantially through a center of stiffness of the movable mass. The displacement detector measures a displacement of the movable mass in a colinear direction with a direction of movement of the movable mass and with a direction of the force applied by the biasing spring and the shape memory alloy. The linear motion stage comprises a housing and at least one guide bar, and wherein a calculated axial expansion of the guide bar is substantially equal to a calculated axial expansion of the base plate.

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1. An instrument for measuring a property of a shape memory alloy, comprising:a base plate; a non-contact movable mass adapted for reversible linear displacement; a force gauge; an actuator for applying a preload force; a biasing spring; a heater for heating the shape memory alloy; and a non-contact

1. An instrument for measuring a property of a shape memory alloy, comprising:a base plate; a non-contact movable mass adapted for reversible linear displacement; a force gauge; an actuator for applying a preload force; a biasing spring; a heater for heating the shape memory alloy; and a non-contact displacement detector; wherein the movable mass and force gauge include first holders for holding the shape memory alloy therebetween, and the actuator and the movable mass include second holders for holding the biasing spring therebetween, whereby the biasing spring and the shape memory alloy are disposed on opposed sides of the movable mass. 2. The instrument of claim 1, wherein the biasing spring and the shape memory alloy are disposed whereby a force applied thereby is applied substantially through a center of stiffness of the movable mass.3. The instrument of claim 2, wherein the displacement detector measures a displacement of the movable mass in a colinear direction with a direction of movement of the movable mass and with a direction of the force applied by the biasing spring and the shape memory alloy.4. The instrument of claim 1, wherein the shape memory alloy is a shape memory alloy wire.5. The instrument of claim 1, wherein the actuator is a micrometer.6. The instrument of claim 1, wherein the movable mass comprises a linear motion stage supported by a non-contact bearing.7. The instrument of claim 6, wherein the linear motion stage comprises a housing and at least one guide bar, and further wherein a calculated axial expansion of the guide bar is substantially equal to a calculated axial expansion of the base plate.8. The instrument of claim 1, wherein the force gauge is a load cell.9. The instrument of claim 1, further including a current detector for measuring a current applied to the shape memory alloy.10. The instrument of claim 1, further including a voltage detector for measuring a voltage applied to the shape memory alloy.11. The instrument of claim 1, further including a data acquisition system for acquiring and processing said current, force, voltage, and displacement data.12. The instrument of claim 3, wherein the displacement detector is a laser interferometer system.13. The instrument of claim 3, wherein the displacement detector is a capacitive displacement sensor.14. An instrument for measuring a property of a shape memory alloy, comprising:a base plate; a non-contact movable mass, said movable mass comprising a linear motion stage supported by a non-contact bearing; a force gauge; an actuator for applying a preload force; a biasing spring; a heater for heating the shape memory alloy; and a non-contact displacement detector, wherein the linear motion stage comprises a housing and at least one guide bar, and further wherein a calculated axial expansion of the guide bar is substantially equal to a calculated axial expansion of the base plate. 15. The instrument of claim 14, wherein the movable mass and force gauge include first holders for holding the shape memory alloy therebetween, and the actuator and the movable mass include second holders for holding the biasing spring therebetween, whereby the biasing spring and the shape memory alloy are disposed on opposed sides of the movable mass.16. The instrument of claim 14, wherein the biasing spring and the shape memory alloy are disposed whereby a force applied thereby is applied substantially through a center of stiffness of the bearings supporting the movable mass.17. The instrument of claim 16, wherein the displacement detector measures a displacement of the movable mass in a colinear direction with a direction of movement of the movable mass and with a direction of the force applied by the biasing spring and the shape memory alloy.18. The instrument of claim 14, wherein the shape memory alloy is a shape memory alloy wire.19. The instrument of claim 14, wherein the actuator is a micrometer.20. The instrument of claim 14, wherein the force gauge is a load cell.21. The instrument of claim 14, further including a current detector for measuring a current applied to the shape memory alloy.22. The instrument of claim 14, further including a voltage detector for measuring a voltage applied to the shape memory alloy.23. The instrument of claim 14, further including a data acquisition system for acquiring and processing said current, force, voltage, and displacement data.24. The instrument of claim 17, wherein the displacement detector is a laser interferometer system.25. The instrument of claim 17, wherein the displacement detector is a linear variable differential transformer transducer.26. A method for repetitive measuring of a thermomechanical property of a shape memory alloy wire, using the instrument of claim 14.27. A method for measuring a thermomechanical property of a shape memory alloy, comprising the steps of:(a) attaching the shape memory alloy at a first end to a force gauge and at a second end to a first side of a non-contact movable mass adapted for reversible linear displacement; (b) attaching a biasing spring at a first end to an actuator and at a second end to a second side of the non-contact movable mass which is opposite the first side; (c) elongating the shape memory alloy to a predetermined length using the actuator; (d) heating the shape memory alloy to a first temperature; (e) measuring a first displacement of the movable mass with a non-contact displacement detector; (f) cooling the shape memory alloy to a second temperature; and (g) measuring a second displacement of the movable mass with the displacement detector; wherein the displacement detector measures a displacement of the movable mass in a colinear direction with a direction of movement of the movable mass and with a direction of the force applied by the biasing spring and the shape memory alloy; and wherein the biasing spring and the shape memory alloy are attached to the movable mass whereby a force applied by the biasing spring and the shape memory alloy is applied substantially through a center of stiffness of the movable mass. 28. The method of claim 27, wherein the shape memory alloy is heated by applying a predetermined current to the shape memory alloy for a predetermined time period.29. The method of claim 27, wherein the non-contact movable mass comprises a linear motion stage supported by a non-contact bearing.30. The method of claim 29, wherein the linear motion stage comprises a housing and at least one guide bar, and further wherein a calculated axial expansion of the guide bar is substantially equal to a calculated axial expansion of the base plate.31. The method of claim 27, wherein the shape memory alloy is a shape memory alloy wire.32. The method of claim 27, further including the steps of:measuring a current applied to the shape memory alloy; measuring a voltage applied to the shape memory alloy; and measuring a force exerted by the shape memory alloy heated to the first temperature. 33. The method of claim 32, further including the step of subjecting the shape memory alloy to a predetermined number of heating and cooling steps.