2. Introduction. Shape Memory Alloy. Operation principle. Types
of SMA Ni-Ti Alloy. Advantages & Disadvantages of Ni-Ti Alloy
Ni-Ti Vs. Copper based SMA. Ni-Ti Vs. stainless steel. Applications
References
3. Smart materials are designed materials that have one or
moreproperties that can be significantly changed in a
controlledfashion by external stimuli, suchas stress, temperature,
moisture, electric or magnetic fields. Types of Smart material:
Shape memory alloy Piezoelectric Thermoelectric materials
Thermochromic Photochromic, etc.
4. SMA are the Materials which have the ability to return to
apredetermined shape when heated or cooled, or below
itstransformation temperature. When it is heated above its
transformation temperature itundergoes a change in crystal
structure which causes it toreturn to its original shape. The most
common shape memory material is an alloy of nickeland titanium
called Nitinol This particular alloy has very good electrical and
mechanicalproperties, long fatigue life, and high corrosion
resistance.
5. SMA has two stable phases1) Austenite (high temperature
phase)2) Martensite (low temperature phase)Fig. 1: Different phases
of a shape memory alloy
6. (a) (b)Fig. 2: (a)Temperature-induced phase transformation
of a shape memory alloy withoutmechanical loading. (b) hysteresis
curve
7. Types of SMA One way SMA Cu-Al-Ni Alloy, Ti51Ni49 Two way
SMA Types of Alloys Ni-Ti Copper
8. The term nitinol is derived from its composition and
itsplace of discovery: (Nickel Titanium-Naval Ordnance Laboratory).
Nitinol is actuator, sensor and heater all in one material Nitinol
thin film actuators have attracted significantdevelopment efforts
in the recent past years. Nitinol films normally less than 10m in
thickness weredeposited on silicon, glass or polymeric substrates
bysputter deposition.
9. Advantages Simple training mechanism High power/weight ratio
Noiseless and silent training High corrosion resistance Can be
controlled with electrical currentDisadvantages Highly controlled
fabrication process required (1% change incomposition results in
20C temperature variation) Low energy conversion efficiency
(5%)
10. .Ni-Ti based SMA Recoverable strain(8%) Shape change
temperaturerange (-200 to +200 C) High resistance to corrosion
Consist of 50% Ni and 50%Ti Expensive material andhighly controlled
Fabricationprocess.Copper based SMA Recoverable strain(4-5%) Shape
change temperaturerange (-200 to +150 C) Low resistance
tocorrosion. Consist of 80% Cu and20% Zn+Al. Less expensive
materialand Metallurgical process.
12. MEMS electrical & thermal Actuator Micro-grippers
Aerospace and Naval Applications Medical Dentistry Repair broken
bones Replace damage discs Cellular phones Robotics arm Fire alarm
sensor Arts
13. Ackland G. J., Atomistic modelling of the shape memory
effect, eprintarxiv:condmat/0509456, september 2005 Ming H. Wu and
L. Mcd. Schetky, INDUSTRIAL APPLICATIONS FOR SHAPE MEMORYALLOYS,
proceedings of the international conference on shape memory and
superelastictechnolgies, pacific grove, california, P.171-182
(2000). Milenko braunovic, senior member, ieee, and c. Labrecque,
shape-memory alloy mechanicalcontact devices, IEEE TRANSACTIONS ON
COMPONENTS, PACKAGING, ANDMANUFACTURING TECHNOLOGY-PART A, VOL. 19,
no. 3, september 1996 Shape-memory alloys metallurgical solution
looking for a problem, metallurgia, vol.51,no. 1, january 1984, pp.
2629 Wu shanqiang, huang peipei, A micro wall-climbing robot using
shape memory alloy, 2011second international conference on digital
manufacturing & automation. Chen-luen shih, bo-kuai lai, harold
kahn, stephen m. Phillips, senior member, IEEE, and arthurH. Heuer,
A robust co-sputtering fabrication procedure forTini shape memory
alloys forMEMS, IEEE JOURNAL OF MICROELECTROMECHANICAL SYSTEMS,
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