ECE5320 Mechatronics Assignment#01: Literature Survey on Sensors and Actuators Topic: Nitinol Actuators

1. ECE5320 MechatronicsAssignment#01: Literature Survey on Sensors and Actuators Topic: Nitinol Actuators Prepared by: Dept. of Electrical and Computer Engineering Utah State University E: anandsmadhu@cc.usu.edu ; T: (435)797-; F: (435)797-3054 (ECE Dept.) W: http:// 3/11/2005

2. Outline • Reference list • To probe further • Major applications • Basic working principle illustrated • A typical sample configuration in application (application notes) • Major specifications • Limitations • And many more relevant issues in applications (such as, how to choose, cost information, where to buy etc.) ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

3. Reference list • http://www.nitinol.info/pages/technology.html • http://turing.ace.uci.edu/~ghertz/2004spring/biorobotics/dennis-herr/dennis-herr-1h.html • http://www.amtbe.com/nitsprings.html • http://www.memry.com/nitinolfaq/nitinolfaq.html • http://www.memry.com/productsservices/semifinished.html • http://www.stanford.edu/~richlin1/sma/sma.html • http://www.nitinol.com/4applications.htm ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

4. Shape Memory Alloy-Untraditional Actuators For Robotics - Michal Vašina. • Scalable rotary actuators with embedded Shape Memory Alloys -Byong-Ho Park, Michael Shantz, Fritz Prinz. • Effects of thermomechanical history on the tensile behavior of Nitinol ribbon -Cynthia L. Lach*a, Travis L. Turner a, Karen M. Taminger***a and Ravi N. Shenoy ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

5. To explore further (survival pointers of web references etc) • http://www.nitinol.info/ • http://www.memory-metalle.de/ • http://www.imagesco.com/catalog/nitinol/nitinol.html • http://www.dynalloy.com/AboutNitinol.html • http://www.devicelink.com/gallery/n00076.html ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

6. Major applications • Coffee machines • Valves • Solar pipes • Safety units • Thermostats • Automotive • Aerospace • Defense. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

7. Nitinol Actuators • Nitinol is an acronym for Nickel Titanium Naval Ordnance Laboratory. • This is a shape memory alloy and it was discovered by William J. Buehler. • Nitinol exhibits a unique phase transition between the Austentite and Martensite phases. • The Austentite phase is a higher temperature and a stronger phase as compared to the Martensite phase. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

8. Super elasticity is achieved when Nitinol is deformed at a a temperature above its Austentite Finish (Af) temperature. • This causes a stress – induced phase transformation from Austentite to Martensite. • The stress – induced Martensite phase is unstable at temperatures above Af and when the stress is removed the material will spring back to its original position. • This is the most attractive property of Nitinol. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

9. Shape Memory • Shape memory occurs when a material is in its Martensitic state and is deformed to a new shape. • When the material is then heated above the Af temperature then it changes back to Austenite and the deformation is lost as the material returns to its original shape. • Up to 8% recovery is possible • All Nitinol exhibits shape memory and super – elastic behavior. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

10. Transformation Temperatures • Martensite start temperature (Ms): the temperature at which the transformation from austenite to Martensite begins on cooling. • Martensite finish temperature (Mf): the temperature at which the transformation from austenite to Martensite finishes on cooling. • Austenite start temperature (As): the temperature at which the transformation from martensite to austenite begins on heating. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

11. Austenite finish temperature (Af): the temperature at which the transformation from Martensite to austenite finishes on heating. Courtesy - http://www.memry.com/nitinolfaq/nitinolfaq.html ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

12. Determining Transformation Temperatures • This is achieved by Differential Calorimetric Scanning which measures the heat flow between the NiTi specimen and the environment in reference to that of an inert interface. Typical DSC curve for fully annealed NiTi alloy Courtesy - http://www.memry.com/nitinolfaq/nitinolfaq.html ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

13. Active temperature transformations can be seen by Bend and Free Recovery test which trace the shape recovery. An illustrated example of a BFR test result. Courtesy : http://www.memry.com/nitinolfaq/nitinolfaq.html ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

14. For actuator or fastener applications the transformation temperatures may be measured by Constant Load Dilatometry. An illustrated example of a CLD test result. Courtesy : http://www.memry.com/nitinolfaq/nitinolfaq.html ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

15. Super elasticity • It is a nonlinear recoverable deformation behavior of NiTi alloys at temperatures above the Af temperature, which arises from the stress-induced Martensitic transformation on loading and the spontaneous reversion of the transformation upon unloading. • A transformation induced strain of up to 6% is recoverable. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

16. An atomic model depicting the mechanism of super elasticity. Courtesy : http://www.memry.com/nitinolfaq/nitinolfaq.html ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

17. Shape memory effect The sequence of temperature change, deformation and shape recovery associated with shape memory effect. Courtesy : http://www.memry.com/nitinolfaq/nitinolfaq.html ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

18. Effect of stress on Transformation Temperatures Effects of stress on Transformation Temperatures Courtesy : http://www.memry.com/nitinolfaq/nitinolfaq.html ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

19. Changes in crystalline structure of SMA ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

20. If the material is heated to temperature At the elements of the SMA stay in a contracted state. • When the temperature goes below Mt the material is deformable once again. • If the temperature is held at At the elements of the SMA stay in contracted state. • When the temperature decreases under Mt the material is deformable once again. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

21. SMA element is extended if it is actuated by a refreshing force. • When the temperature is increased over point At, SME of the material can be completely destroyed. • Conversion inside the SMA materials isn’t thermodynamically reversible process. • There is energy dissipation due to internal friction and creation of structural defects. The result of these processes is a temperature hysteresis loop. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

22. Hysteresis Loop in SMA ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

23. Stress Strain curve of the NiTi alloy ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

24. Distributed shapes of Nitinol NiTinol is distributed in many shapes. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

25. Application of SMA ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

26. Each leg of the above robot has two degrees of freedom and the movement of the leg is provided by three NiTinol drives. • The horizontal movement is realized by the antagonistic connection of two wires. • The vertical movement is realized by connection of SMA wire and a spring. • The method of PWM, which is generated by the microprocessor and which the peripheral electronic switches are connected to, is used for the control of the actuator's contraction. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

27. Conclusion • The drives based on metals with the shape memory effect are the subject of research in many institutions, which are interested in the research of robotics. • Research in this area is promising and attractive both from practical and theoretical point of view. ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators