PROPERTIES AND APPLICATION OF SHAPE MEMORY ALLOY

1. NAME : VAISAKH M
ROLL NO : 67
S7 MA
Department of Mechanical Engineering
Mar Athanasius College of Engineering
Kothamangalam
AUGUST 2015
SHAPE MEMORY ALLOYS AND ITS APPLICATION
IN VARIOUS
AVIATION FIELD
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2. INTRODUCTION
 Class of smart materials
 Shape memory alloys are metal alloys that remember
their original shape
 If deformed, they recover their original shape upon
heating
 One type of shape memory alloy is Ni-Ti (Nitinol)
 It has two stable phases, the high temperature Austenite
phase and the low temperature martensitic phase
 It is quite fascinating field of research mainly in
aviation technology
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3. PRINCIPLE
 The shape change involves a solid state phase change
involving molecular rearrangement between Martensite
and Austenite
 If mechanical load is applied to the material in the state
of twinned Martensite is possible to detwin the
Maretensite
 Upon releasing the load, material remains deformed.
 A subsequent heating of the material to a temperature
above austenite finish temperature (Af) will result in
reverse phase transformation and will lead o complete
shape recovery
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4. THERMALLY INDUCED STRESS
TRANFORMATONS IN SMA’S
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5. INTERPRETATION OF SHAPE MEMORY
EFFECT
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Fig. 2 Temperature hysteresis in phase transition
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6. PHASE TRANSFORMATION
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Fig.3 Temperature Vs Load variation graph
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7. SUPER ELASTIC BEHAVIOUR OF
SHAPE MEMORY ALLOYS
Occurs when an alloy is completely in Austenite
phase
Super elasticity is not dependent on temperature
When load is increased to a point, the alloy
transitions from the Austenite phase to the
detwinned Martensite phase
Once load is removed, the alloy returns to its
original Austenite phase shape showing a rubber
like effect
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8. 5500 lbf LOX-Methane thruster prototype
SHAPE MEMORY ALLOY
SHOWING SUPERELASTICITY
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Fig.4 Sress Vs Temperature Graph
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9. LEAK HANDLING IN AIRCRAFT PIPE
SYSTEMS
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Fig 5a. Coupling expands Fig 5b. Shrinkage exposed to heat
Fig 5c. Making close fits
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10. MERITS OF SMA TUBE FITTING
 Memory alloy tube fitting is lighter over 60% than traditional
tube fittings
 Its compression performance can reach 5000psi,special memory
tube can reach 8000psi
 Compact structure
 High sealing performance
 Cost of memory alloy tube connection is 40% cheaper than
traditional tube assembling
 Anti corrosion properties of TiNi based shape memory alloys
are excellent
 Strong adaptability and suitable for connection among
dissimilar materials which cannot be welded
 Convenient to install and operate and it takes only 15-30
seconds to complete the joint and sealing of tubes
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11. SELF DEPLOYING ANTENNA
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Fig 6. SMA satelite antenna

12. MERITS SMA DEPLOYED STRUCTURES
Mass and volume saving
Retraction capability
Noiseless operation
Sensing capability
Higher reliability
High electrical resistivity
Large recoverable strains
Design flexibility
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13. VARIABLE GEOMETRY CHEVRON(VGC)
 SMA’s can also be applied to engines to reduce noise
 To reduce noise some engineers install chevron onto
engines to mix the flow of exhaust gases and reduce the
engine noise
 SMA beams can be embedded into chevrons
 When they become hot at takeoff, the 14 inch long
chevrons bend into the engine fan stream altering the
high speed air mixing effectively hushing noise by half
 They can make planes lighter and hence more fuel
efficient because less sound insulation is needed
between engines and passengers
 Provides communities around te airports more peace
and quite
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14. Fig 6. Variable Geometry chevron
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15. SPACE CRAFT RELEASE MECHANISMS
 The release mechanism is what holds on to the object
before it is released into space.
 It is the force holding it down, and what lets it go
 SMAs are used in space crafts for problems of release,
actuation, and vibration mitigation during either launch
or micro gravity zero atmosphere environment
 Actuation is the actual act of propelling, which causes
vibration mitigation
 Slow actuation is caused by the SMA’s gradual heating,
which makes it more suitable for low shock release
operations in space crafts
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16. VARIABLE AREA FAN NOZZLE (VAFN)
Larger diameter of nozzle at takeoff can reduce
jet velocity reducing noise
Adjusting the nozzle diameter in the cruise helps
in reducing fuel consumption
Boeing tested VAFN is capable of 20% area
change
SMA actuators were used to position 12 panels at
the nozzle exit
SMA actuators are designed to expand nozzle
when heated , are attached to half of the panels
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17. Fig 7.Variable area nozzle design concept
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18. CONCLUSION
 In the aviation field, the application of SMA undergoes
constant breakthrough in several directions from the
application of independent properties of material to its
combination with electonic and hydraulic technology
 SMA materials could integrate sensing, control and
drive into one body because of its unique memory
effect and high energy density.
 It can be controlled flexibly, actuated compliantly, and
produce no vibration and noise
 Another aspect is to increase the Self adapting ability of
SMA materials at high and low temperatures, so it
could be applied more widely
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19. REFERENCES
Andrew Peter Jar dine, Shape memory wire
actuated aircraft door seal[P].American Patent
,No.US6009669
AEROFIT INC America, The military,
aviation, aerospace, energy, marine tube
fittings and accessories memory alloy.
The plane structure of high stiffness driven by
shape memory alloy. Chinese Patent
No.201080034831
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20. THANK YOU
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