SUMMER INTERNSHIP PROJECT-II
SUBJECT CODE: PWME681
ON
SHAPE MEMORY ALLOY
Submitted in the requirement of partial fulfilment for
The 3rd year 6th Semester course of
BACHLOR OF TECHNOLOGY
IN
MECHANICAL ENGINEERING
Submitted By
Moinak Roy(15800718132)
Sudarshan Dey(15800719014)
Under the Guidance of
Mr. Suman Mandal
DEPARTMENT OF MECHANICAL ENGINEERING
MALLABHUM INSTITUTE OF TECHNOLOGY
BISHNUPUR , BANKURA
West Bengal
2021
DEPERTMENT OF MECHANICAL ENGINEERING
MALLABHUM INSTITUTE OF TECHNOLOGY
BISHNUPUR,BANKURA
WEST BENGAL
CIRTIFICATE
This is to certify that the Summer Internship Project -II report entitled “SHAPE MEMORY
ALLOY” carried out by MOINAK ROY, SUDARSHAN DEY 3rd year 6th semister B.Tech.
Mechanical Engineering student of section 2020-21 in partical fulfilment of B.Tech 3rd year
6th semister course of Bacholer of Technology in Mechanical Engineering.
MR.SUMAN MANDAL
ASSISTANT PROFESSOR
Depertment of Mechanical engineering
Mallabhum Institute Of Technology
Guide
HEAD OF THE DEPERTMENT
Depertment of Mechanical Engineering
Mallabhum Institute of Technology
ACKNOWLEDGEMENT
We would like to express our sincere gratitude to Mr. Suman Mandal, Assistant professor,
Mechanical Engineering Department. Mallabhum Institute of Technology. Bishnupur for his
guidance and help extended at every step of this project work we are deeply indebted to him
for giving us a definite direction and moral support
would like to thanks Mr. Suprakash Mondal, Head of the Mechanical Engineering
Department for providing us this opportunity to prefer a report on this topic selected of our
interest and for guiding us by giving his valuable comments for concening manuscript
Last but not the least we extend our gratitude to other faculty members of the Department for
their valuable advice in every step for successful completion of this report
By:
Moinak Roy
Sudarshan Dey
Date:-
CONTENTS
CERTIFICARTE
ACKNOWLEDGEMENT
LIST OF FIGURES
LIST OF TABLES
ABSTRACT
Chapter 1…………………………………………………………………………….1
INTRODUCTION…………………………………………………………………..2
Chapter 2…………………………………………………………………………….3
ORIGIN OF THE SHAPE MEMORY EFFECT…………………………………. .4
Chapter 3……………………………………………………………………………6
SMA BEHAVIOUR………………………………………………………………..7
Chapter 4…………………………………………………………………………... 8
THE TECHNOLOGY……………………………………………………………...9
Chapter 5…………………………………………………………………………..12
ONE WAY AND TWO WAY SHAPE MEMORY …………………………...…13
Chapter 6……………………………………………………………………….….15
MATERIALS AND APPLICATION OF SHAPE MEMORY ALLOY…….……16
LIST OF FIGURES
Sl.No
Fig.No
Description
Page.No
1
Fig.no:1
Binary phase diagram of Ti-Ni alloy
4
2
Fig.no:2
Stress-strain curves for a Ti-50.6Ni alloy
7
3
Fig.no:3
SMA tyre
9
4
Fig.no:4
SMA tyre
9
5
Fig.no:5
Martensite vs Austenite of shape memory alloy
10
6
Fig.no:6
One way and two way shape memory
13
7
Fig.no:7
Stress vs strain graph
14
8
Fig.no:8
SMA Material
16
9
Fig.no:9
NASA rover
18
10
Fig.no:10
Wheel of NASA rover
18
LIST OF TABLES
SL
NO
Table No
Description
Page no
1
Table.1
Alloys having a shape memory effect
11
ABSTRACT
Shape memory alloys (SMAs) show a particular behaviour that is the ability to recuperate
the original shape while heating above specific critical temperatures (shape memory effect) or
to withstand high deformations recoverable while unloading (pseudoelasticity). In many cases
the SMAs play the actuator’s role. Starting from the origin of the shape memory effect, the
mechanical properties of these alloys are illustrated. This paper presents a review of SMAs
applications in the aerospace field with particular emphasis on morphing wings (experimental
and modelling), tailoring of the orientation and inlet geometry of many propulsion system,
variable geometry chevron for thrust and noise optimization, and more in general reduction of
power consumption. Space applications are described too: to isolate the micro-vibrations, for
low-shock release devices and self-deployable solar sails. Novel configurations and devices
are highlighted too.
Chapter 1
INTRODUCTION
1
INTRODUCTION
Shape memory alloys (SMAs) are metals able to recuperate a preset shape just while heating
up to a critical transformation temperature. The physical principle they are based on is a
particular martensitic transformation (thermoelastic) occurring in some metallic alloys.
The list includes but is not limited to NiTi, CuAlNi, CuZnAl, AuCd, and many others. Buehler
et al. in 1963 were the first to evidence the shape memory effect in near equiatomic Ti-Ni
alloys. The shape memory effect was found earlier in Au-47.5% Cd and In-Tl but without
attracting attention from the researchers. On the contrary, equiatomic Ni-Ti alloys became
popular thanks to Naval Ordinance Laboratory, hence the name Nitinol.
The real understanding of the phenomena occurring during the martensitic transformation was
not immediate. The main reason may be ascribed to the complexity of the Ti-Ni phase diagram
(Figure 1) and to the formation of a multiplicity of precipitates under certain heat treatments
(TiNi, Ti2Ni, TiNi3, Ti2Ni3, Ti3Ni4). Moreover, the R-phase (rhombohedral) transformation,
considered to be a pre-martensitic phenomenon, appears under certain conditions while
cooling. Now it is established that the R-phase itself is a martensitic transformation and
contends with the successive martensitic transformation. Due to the excellent mechanical
properties, corrosion, and abrasion resistance Ni-Ti shape memory alloys have been widely
employed in many technological applications: stent, guide wire, antenna for mobile phones,
coffee maker, orthodontic wire, flap for air-conditioner, and many others. The main aim of this
review is to identify and exemplify a detailed list of novel applications of SMA in the aerospace
field in the most updated manner without the claim of comprehensiveness, according to
available recent literature in terms of relevance, number of articles, and novelty of the
proposals. Ni-Ti alloys are the most employed ones, but the subject is not limited to them.
2
Chapter 2
ORIGIN OF THE SHAPE MEMORY EFFECT
3
ORIGIN OF THE SHAPE MEMORY EFFECT
For the comprehension of the basic principles regarding the shapememory effect and
pseudoelasticity, many contributions are useful. The crystallography of martensite, the
transformation temperatures, and rate of martensite formation are discussed in details by
Nishiyama
Figure 1. Binary phase diagram of Ti-Ni alloy . Figure 1Reprinted fromMaterials,Vol. 12
(5),Chekotu, J.C.; Groarke, R.; O’Toole, K., Brabazon, D., Advances in Selective Laser
Melting of Nitinol Shape Memory Alloy Part Production, 2019.
The macrostructure consequences of the microstructure and the shape memory effect have been
highlighted by Bhattacharya .The design of some shape memory alloy actuators were focused
on by Otsuka and Wayman .National Aeronautics and Space Administration (NASA) report
SP5111 published in 1972 provides experimental results, although the base mechanism was
not fully understood at that time .The phase transformation occurring on an SMA is peculiar
because it coexists with great strain and is fully recoverable, so that in a uniaxial tensile test in
NiTi it can reach also 10% .For this reason, SMAs belong to the family of the “active materials”
.SMAs can also provide high forces and wide displacements when activated, if compared to
other active materials. Novel application fields continue to be identified .Biomedical industry
is the most served one, together with the aerospace industry. SMAs can be identified also into
the class of the “smart materials”: an SMA component, with structural or functional purpose,
can make a system simpler in comparison with the same manufactured piece adopting
conventional know-how (for instance electromechanical or hydraulic). High activation loads
and displacements generates great energy density. These properties are welcome especially in
the aerospace field, hence the main reason of this review. The technological requirements of
the aerospace field are more important than any considerations about the technology cost and
this aspect can be identified as the real reason of the success of SMAs.
4
CRYSTAL STRUCTURE
Many metals have several different crystal structures at the same composition, but most metals
do not show this shape-memory effect. The special property that allows shape-memory alloys
to revert to their original shape after heating is that their crystal transformation is fully
reversible. In most crystal transformations, the atoms in the structure will travel through the
metal by diffusion, changing the composition locally, even though the metal as a whole is made
of the same atoms. A reversible transformation does not involve this diffusion of atoms, instead
all the atoms shift at the same time to form a new structure, much in the way a parallelogram
can be made out of a square by pushing on two opposing sides. At different temperatures,
different structures are preferred and when the structure is cooled through the transition
temperature, the martensitic structure forms from the austenitic phase.
5
Chapter 3
SMA Behaviour
6
SMA Behaviour
In an extremely simplified manner, the main phases involved in an SMA are being austenite
stable at higher temperature (parent phase) and martensite stable at lower temperature with
tetragonal or monocline structure [1,8,12]. A lot of stress-strain curves obtained in tensile tests
for the Ti-50.6Ni alloy at different and constant temperatures are reported in Figure 2 [13],
highlighting the mechanical behaviour from low temperature to high temperature. At lower
temperatures (Figure 2a–i), it is evident the shape memory effect: after an initial linear stage a
plateau of stress is evident, followed by residual strain while unloading. After that, the shape
recovery (not shown in the graph) on heating starts at As (Austenite start temperature) and
finishes at Af (Austenite finish temperature). At temperatures higher than Af (Figure 2j–p),
austenite is the only stable phase. Tensile behaviour exhibits a loading path with a plateau at
higher stress than that in the martensitic phase. During unloading, the strain is fully recovered
and the classic flag-type diagram is evidenced, without the necessity of further heating. The
higher the temperature, the higher the temperature, the higher the level of stress for the plateau.
Figure 2.Stress-strain curves
for a Ti-50.6Ni alloy showing
shape memory effect (a–i) and
pseudo elastic effect (j–p)
.Figure 2 Reprinted from Scripta
Metallurgica, Vol. 15,Miyazaki,
S.; Otsuka, K.; Suzuki, Y.,
Transformation pseudoelasticity
and deformation behaviour in a
Ti-50.6Ni alloy, 1981, with
permission from Elsevier.
The aerospace industry is
actively looking for novel
solutions and applications based
on the
integration of the SMAs in the
actual technologies as well as the
definition and development of new ones. SMA adoption allows to increase the simplicity of
the systems as well as to reduce the weight and the volume of such active devices allowing it
to achieve more compact structures. SMAs are attractive as a solution to complex engineering
problems, along with high actuation stresses and strains due to their intrinsic great
power/weight ratio. Integrating actuators and structures means it is possible to achieve high
reliability and compact arrangements, reliable also for a high number of activation cycles
[14,15]. Systems activated by SMAs have been widely examined in many studies and pieces
of research in substitution of standard actuation systems, hydraulic and electric.
7
Chapter 4
The Technology
8
The Technology
This innovation comprises a non-pneumatic, compliant tire utilizing shape memory alloys
(mainly NiTi and its derivatives) as load bearing components. These shape memory alloys are
capable of undergoing significant reversible strain (up to 10%), enabling the tire to withstand
an order of magnitude more deformation than other non-pneumatic tires before undergoing
permanent deformation. Commonly used elastic-plastic
materials (e.g. spring steels, composites, etc.) can only
be subjected to strains on the order of ~ 0.3-0.5% before
yielding. Hence, the use of a NiTi shape memory alloy
produces a superelastic tire that is virtually impervious
to plastic deformation. In addition, the utilization of
shape memory alloys provides enhanced control over
the effective stiffness as a function of the deformation,
providing increased design versatility. For instance, the
Glenn Superelastic Tire can be made to soften with
increased deflection, reducing the amount of energy
transferred to the vehicle during high deformation
events. In addition, the use of shape memory alloys in
the form of radial stiffeners, as opposed to springs,
provides even more load carrying potential and
improved design flexibility. This type of compliant tire
would allow for increased travel speeds in off-road
applications.
FIG:3
FIG:4
9
Martensite vs Austenite of shape memory alloy
Shape memory alloys display two distinct crystal structures or phases. Temperature
and internal stresses (which play a part in super-elasticity) determine the phase that
the SMA will be at. Martensite exists at lower temperatures, and austenite exists at
higher temperatures. When a SMA is in martensite form at lower temperatures, the
metal can easily be deformed into any shape. When the alloy is heated, it goes
through transformation from martensite to austenite. In the austenite phase, the
memory metal "remembers" the shape it had before it was deformed. From the
stress vs. temperature graph below, one can see that at low stress and low
temperature, martensite exists. At higher temperature and higher stress, austenite
exists.
Stress vs.
NiTinol
Temperature graph for
FIG:5
Memory alloys also demonstrate great rates of super-elasticity. For example, eyeglass frames
are in a martensite phase. Bending the arms in half (at room temperature) introduces a phase
change at the bend to austenite. Austenite is not stable at room temperature, and because
systems always seek lower energy states, the austenite will change back to the martensite phase,
and to do this, the arm must bend back.
The most common memory metal is called NiTinol, consisting of equal parts of nickel and
titanium.
10
Alloys having a shape memory effect
Composition
Atomic or Weight Percent
Transformation
Temperature Range (Celsius)
-190 to -50
30 to 100
-140 to 100
Cu - Sn
44/49 at.%
46.5/50 at.%
14/14.5 wt%
3/4.5 wt%
approx. 15 at%
Cu - Zn
38.5/41.5 wt%
-180 to -10
Cu - Zn - (Si,Sn,Al)
In - Ti
Ni - Al
Ni - Ti
Fe - Pt
Mn - Cu
a few wt.% of (Si, Sn,Al)
18/23 at%
36/38 at%
49/51 at%
approx. 25 at% Pt
5/35 at% Cu
-180 to 200
60 to 100
-180 to 100
-50 to 110
approx. -130
-250 to 180
Alloys
Ag - Cd
Au - Cd
Cu - Al - Ni
-120 to 30
PROPERTIES
The copper-based and NiTi-based shape-memory alloys are considered to be engineering
materials. These compositions can be manufactured to almost any shape and size.
The yield strength of shape-memory alloys is lower than that of conventional steel, but some
compositions have a higher yield strength than plastic or aluminum. The yield stress for Ni Ti
can reach 500 MPa. The high cost of the metal itself and the processing requirements make it
difficult and expensive to implement SMAs into a design. As a result, these materials are used
in applications where the super elastic properties or the shape-memory effect can be exploited.
The most common application is in actuation.
One of the advantages to using shape-memory alloys is the high level of recoverable plastic
strain that can be induced. The maximum recoverable strain these materials can hold without
permanent damage is up to 8% for some alloys. This compares with a maximum
strain 0.5% for conventional steels.
11
Chapter 5
One-way and two-way shape memory
12
One-way and two-way shape memory
Shape-memory alloys have different shape-memory effects. Two common effects are a oneway and two-way shape memory. A schematic of the effects is shown below.
FIG:6
The procedures are very similar: starting from martensite (a), adding a reversible deformation
for the one-way effect or severe deformation with an irreversible amount for the two-way (b),
heating the sample (c) and cooling it again (d).
One-way memory effect
When a shape-memory alloy is in its cold state (below As), the metal can be bent or stretched
and will hold those shapes until heated above the transition temperature. Upon heating, the
shape changes to its original. When the metal cools again, it will retain the shape, until
deformed again.
With the one-way effect, cooling from high temperatures does not cause a macroscopic shape
change. A deformation is necessary to create the low-temperature shape. On heating,
transformation starts at As and is completed at Af (typically 2 to 20 °C or hotter, depending on
the alloy or the loading conditions). As is determined by the alloy type and composition and
can vary between −150 °C and 200 °C.
Two-way memory effect
The two-way shape-memory effect is the effect that the material remembers two different
shapes: one at low temperatures, and one at the high temperature. A material that shows a
shape-memory effect during both heating and cooling is said to have two-way shape memory.
This can also be obtained without the application of an external force (intrinsic two-way effect).
The reason the material behaves so differently in these situations lies in training. Training
implies that a shape memory can "learn" to behave in a certain way. Under normal
circumstances, a shape-memory alloy "remembers" its low-temperature shape, but upon
heating to recover the high-temperature shape, immediately "forgets" the low-temperature
shape. However, it can be "trained" to "remember" to leave some reminders of the deformed
low-temperature condition in the high-temperature phases. There are several ways of doing
this.[15] A shaped, trained object heated beyond a certain point will lose the two-way memory
effect.
13
FIG:7
14
Chapter 6
Materials
AND
Applications for Shape Memory alloys
15
MATERIALS
A variety of alloys exhibit the shape-memory effect. Alloying constituents can be adjusted to
control the transformation temperatures of the SMA. Some common systems include the
following (by no means an exhaustive list):
•
•
•
Ag-Cd 44/49 at.% Cd
Au-Cd 46.5/50 at.% Cd
Co-Ni-Al
•
•
•
•
•
•
•
•
•
•
FIG:8
•
•
•
•
•
•
•
•
Co-Ni-Ga
Cu-Al-Be-X(X:Zr, B, Cr, Gd)
Cu-Al-Ni 14/14.5 wt.% Al, 3/4.5 wt.% Ni
Cu-Al-Ni-Hf
Cu-Sn approx. 15 at.% Sn
Cu-Zn 38.5/41.5 wt.% Zn
Cu-Zn-X (X = Si, Al, Sn)
Fe-Mn-Si
Fe-Pt approx. 25 at.% Pt
Mn-Cu 5/35 at.% Cu
Ni-Fe-Ga
Ni-Ti approx. 55–60 wt.% Ni
Ni-Ti-Hf
Ni-Ti-Pd
Ni-Mn-Ga[46]
Ni-Mn-Ga-Cu
Ni-Mn-Ga-Co
Ti-Nb
Applications for Shape Memory alloys
Bioengineering:
Bones: Broken bones can be mended with shape memory alloys. The alloy plate
has a memory transfer temperature that is close to body temperature, and is
attached to both ends of the broken bone. From body heat, the plate wants to
contract and retain its original shape, therefore exerting a compression force on the
broken bone at the place of fracture. After the bone has healed, the plate continues
exerting the compressive force, and aids in strengthening during rehabilitation.
Memory metals also apply to hip replacements, considering the high level of superelasticity. The photo above shows a hip replacement.
Reinforcement for Arteries and Veins: For clogged blood vessels, an alloy tube is
crushed and inserted into the clogged veins. The memory metal has a memory
transfer temperature close to body heat, so the memory metal expands to open the
clogged arteries.
16
Dental wires: used for braces and dental arch wires, memory alloys maintain their
shape since they are at a constant temperature, and because of the super elasticity
of the memory metal, the wires retain their original shape after stress has been
applied and removed.
Anti-scalding protection: Temperature selection and control system for baths and
showers. Memory metals can be designed to restrict water flow by reacting at
different temperatures, which is important to prevent scalding. Memory metals will
also let the water flow resume when it has cooled down to a certain temperature.
Fire security and Protection systems: Lines that carry highly flammable and toxic
fluids and gases must have a great amount of control to prevent catastrophic
events. Systems can be programmed with memory metals to immediately shut
down in the presence of increased heat. This can greatly decrease devastating
problems in industries that involve petrochemicals, semiconductors,
pharmaceuticals, and large oil and gas boilers.
Golf Clubs: a new line of golf putters and wedges has been developed using sma.
Shape memory alloys are inserted into the golf clubs. These inserts are super
elastic, which keep the ball on the clubface longer. As the ball comes into contact
with the clubface, the insert experiences a change in metallurgical structure. The
elasticity increases the spin on the ball, and gives the ball more "bite" as it hits the
green.
Helicopter blades: Performance for helicopter blades depend on vibrations; with
memory metals in micro processing control tabs for the trailing ends of the blades,
pilots can fly with increased precision.
Eyeglass Frames: In certain commercials, eyeglass companies demonstrate eyeglass
frames that can be bent back and forth, and retain their shape. These frames are
made from memory metals as well, and demonstrate super-elasticity.
Tubes, Wires, and Ribbons: For many applications that deal with a heated fluid
flowing through tubes, or wire and ribbon applications where it is crucial for the
alloys to maintain their shape in the midst of a heated environment, memory metals
are ideal.
17
Application of SMA in NASA Mars Rover (curiosity)
FIG:9
SMA has a great application in the curiosity rover wheel as because mars have a very rough
terrain and the temperature of mars is very low (approx:- 80 degrees Fahrenheit) So, it is very
difficult for the material of the wheel to withstand the rough environment of mars . Because
rubber looses it’s elastic property and became a brittle material and for this reason scientist
has developed a wheel made of Shape Memory Alloy. This wheel/ tyre is also known as
super elastic tyre.
FIG:10
The novel use of shape memory alloys capable of undergoing high strain as load bearing
components, instead of typical elastic materials, results in a tire that can withstand excessive
deformation without permanent damage. Using shape memory alloy as radial stiffening
elements can also increase the load carrying capacity of the tire. The Superelastic Tire offers
traction equal or superior to conventional pneumatic tires and eliminates both the possibility
of puncture failures and running "under-inflated", thereby improving automobile fuel
18
efficiency and safety. Also, this tire design does not require an inner frame which both
simplifies and lightens the tire/wheel assembly.
Benefits
➢ Safe: Eliminates the possibility of puncture failure
➢ Strong: Can withstand excessive deformation
➢ Robust: Can be configured for high traction on various terrains
➢ Simple: Eliminates the need for air
➢ Versatile: Tire stiffness can be designed to limit energy transferred to vehicle
➢ Lightweight: No inner frame needed for the tire/ wheel assembly.
Practical limitations
SMA have many advantages over traditional actuators, but do suffer from a series of
limitations that may impede practical application. In numerous studies, it was emphasised
that only a few of patented shape memory alloy applications are commercially successful due
to material limitations combined with a lack of material and design knowledge and associated
tools, such as improper design approaches and techniques used. The challenges in designing
SMA applications are to overcome their limitations, which include a relatively small usable
strain, low actuation frequency, low controllability, low accuracy and low energy efficiency.
19
Summary
In the last two decades, many applications of SMAs in the aerospace field have been identified,
designed, modeled, and tested. Many others will be conceived and developed in the near future.
The present review confirms that SMAs attracted researcher’s attention especially in the
applications in which the added value is more important than the pure economic saving.
Extensive studies, results of analytical and numerical modeling, and experimental tests have
been found in literature regarding SMA. In many cases, the SMAs play the role of an actuator.
Starting from the basic principle and the mechanical behavior (shape memory effect and
pseudoelastic), many applications regarding the wing morphing have been presented
(experimental and modeling) as well tailoring of the inlet geometry of various propulsion
systems. Variable geometry chevron actuated by SMA has been illustrated for thrust, noise,
and general e_ciency optimization. Also, space applications have been described for isolating
the micro-vibrations, for low-shock release devices and self-deployable solar sails. The
development stage in many cases is limited to prototypes tested in laboratories or in wind
tunnels, with only a few actually flown and even fewer in use. The main limitations may be
ascribable to the higher weight, in some cases complexity of the systems, and the structural and
functional fatigue phenomena in cycling applications. In the near future, many other SMAbased applications will be identified and conceived in which the actuation due to the shape
memory effect or the pseudoelasticity will be based on.
20
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[CrossRef]
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10. GOOGLE images
11. wikipedia