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ECE5320 Mechatronics Assignment#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.

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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

outline
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

reference list
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

slide4
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

to explore further survival pointers of web references etc
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

major applications
Major applications
  • Coffee machines
  • Valves
  • Solar pipes
  • Safety units
  • Thermostats
  • Automotive
  • Aerospace
  • Defense.

ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

nitinol actuators
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

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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

shape memory
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

transformation temperatures
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

slide11
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

determining transformation temperatures
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

slide13
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

slide14
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

super elasticity
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

slide16

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

shape memory effect
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

effect of stress on transformation temperatures
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

changes in crystalline structure of sma
Changes in crystalline structure of SMA

ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

slide20
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

slide21
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

hysteresis loop in sma
Hysteresis Loop in SMA

ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

stress strain curve of the niti alloy
Stress Strain curve of the NiTi alloy

ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

distributed shapes of nitinol
Distributed shapes of Nitinol

NiTinol is distributed in many shapes.

ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

application of sma
Application of SMA

ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

slide26
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

conclusion
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