Dimitris C.Lagoudas Shape Memory Alloy Research Team Aerospace Engineering Department Texas A&M University Intellige nt Systems Laboratory An An Introduction Introduction to Shape to Shape Memory Alloys Memory Alloys
Dimitris C.Lagoudas Shape Memory Alloy Research Team Aerospace Engineering Department Texas A&M University Intelligent Systems Laboratory An Introduction.
Dec 21, 2015
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Dimitris C.Lagoudas
Shape Memory Alloy Research Team
Aerospace Engineering DepartmentTexas A&M University
Intelligent Systems Laboratory
An Introduction to An Introduction to Shape Memory Shape Memory AlloysAlloys
Texas A&M University Active Materials Laboratory
What are Shape Memory Alloys? What are Shape Memory Alloys?
•Shape Memory Alloys (SMAs) are metallic alloys that undergo a solid-to-solid phase transformation which can exhibit large recoverable strains. Example: Nitinol
Martensite•Low temperature phase•Monoclinic Crystal Structure
Austenite• High temperature phase•Cubic Crystal Structure
Twinned Martensite Detwinned Martensite
Texas A&M University Active Materials Laboratory
Thermally Induced Phase Transformation in Thermally Induced Phase Transformation in SMAsSMAs
Mf Ms As Af
AusteniteMartensite TEMPERATURE
Mf Ms As Af
AusteniteMartensite TEMPERATURE
(twinned)
(twinned)
Characteristic temperatures:Mf=Martensitic FinishMs=Martensitic StartAs=Austenitic StartAf=Austenitic Finish
Texas A&M University Active Materials Laboratory
Shape Memory Effect: Shape Memory Effect: Stress Free Shape RecoveryStress Free Shape Recovery
TEMPERATURE
ST
RE
SS
Mf Ms As Af
TEMPERATURE
ST
RE
SS
Mf Ms As Af
Twinned Martensite (unstressed)
Detwinned Martensite (stressed - deformed)
Detwinned Martensite (stressed - deformed)
Detwinned Martensite (unstressed - deformed)
Austenite (undeformed)
Texas A&M University Active Materials Laboratory
The Shape Memory EffectThe Shape Memory Effect
T
Cooling
Detwinning
Heating/Recovery
Texas A&M University Active Materials Laboratory
Shape Memory Effect: Shape Shape Memory Effect: Shape Recovery Under StressRecovery Under Stress
TEMPERATURE
STR
ESS
Mf Ms
Detwinned Martensite(stressed) Austenite
As Af
Texas A&M University Active Materials Laboratory
The Pseudoelastic EffectThe Pseudoelastic EffectS
TR
ES
S
TEMPERATURE
Mf Ms As Aff s s f
Austenite
Detwinned Martensite(stressed)
Texas A&M University Active Materials Laboratory
The Pseudoelastic EffectThe Pseudoelastic Effect
Mf
Ms
Af
As
Texas A&M University Active Materials Laboratory
SMA Demonstrations and ApplicationsSMA Demonstrations and Applications
Floral Arrangement SMA Actuated Butterfly: SMA Linear Actuator
Thermobile™ Demonstrator:SMA Properties/Thermodynamics
Texas A&M University Active Materials Laboratory
Where Are SMAs Used?Where Are SMAs Used?
Texas A&M University Active Materials Laboratory
SMAs in Bio-medical DevicesSMAs in Bio-medical Devices
Texas A&M University Active Materials Laboratory
SMA Space ApplicationsSMA Space Applications
Landis G.A., NASA Lewis Research Center, “Materials Adherence Experiment Results from Mars Pathfinder”, 26th Photovoltaic Specialists Conference, 1997
SMA RibbonBolt released
Texas A&M University Active Materials Laboratory
Links
Flexible tail
Joints
Model withoutskin
Model withskin
Rigid nose
SMAs as Linear ActuatorsSMAs as Linear Actuators
Texas A&M University Active Materials Laboratory
Miniaturized Walking RobotMiniaturized Walking Robot
The implementation of SMA wires coupled with a simple DC control system can be used to drive small objects without the addition of relatively heavy motors, gears, or drive mechanisms.
Texas A&M University Active Materials Laboratory
Biomimetic HydrofoilBiomimetic Hydrofoil
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