Technical Seminar Report

Technical Seminar Report Date: 24th March, 2012

Submitted By- TARINI PRASAD MISHRA Hall Ticket No- 08261A1856, 4th Year, MME

INTRODUCTION TO SHAPE MEMORY ALLOYS

1. Background

Metals are characterized by physical qualities as tensile strength, malleability and

conductivity. In the case of shape memory alloys, we can add the anthropomorphic qualities of

memory and trainability. Shape memory alloys exhibit what is called the shape memory effect. If

such alloys are plastically deformed at one temperature, they will completely recover their

original shape on being raised to a higher temperature. In recovering their shape the alloys can

produce a displacement or a force as a function of temperature. In many alloys combination of

both is possible. We can make metals change shape, change position, pull, compress, expand,

bend or turn, with heat as the only activator. Key features of products that possess this shape

memory property include: high force during shape change; large movement with small

temperature change; a high permanent strength; simple application, because no special tools are

required; many possible shapes and configurations; and easy to use - just heat [1]. Because of

these properties shape memory alloys are helping to solve a wide variety of problems. In one

well–developed application shape memory alloys provide simple and virtually leakproof

couplings for pneumatic or hydraulic lines [2]. The alloys have also been exploited in

mechanical and electromechanical control systems to provide, for example, a precise mechanical

response to small and repeated temperature changes [3]. Shape memory alloys are also used in a

wide range of medical and dental applications (healing broken bones, misaligned teeth . . )[2, 4].

Shape Memory Alloys (SMA's) are novel materials which have the ability to return to a

predetermined shape when heated. When an SMA is cold, or below its transformation

temperature, it has a very low yield strength and can be deformed quite easily into any new

shape--which it will retain. However, when the material is heated above its transformation

temperature it undergoes a change in crystal structure which causes it to return to its original

shape. If the SMA encounters any resistance during this transformation, it can generate

extremely large forces. This phenomenon provides a unique mechanism for remote actuation.

2. History

First observations of shape memory behaviour were in 1932 by ¨ Olander in his study of “rubber

like effect” in samples of gold–cadmium [5] and in 1938 by Greninger and Mooradian in their



study of brass alloys (copper–zinc) [1, 5]. Many years later (1951) Chang and Read first reported

the term “shape recovery” [5]. They were also working on gold–cadmium alloys. In 1962

William J. Buehler and his co–workers at the Naval Ordnance Laboratory discovered shape

memory effect in an alloy of nickel and titanium. He named it NiTiNOL (for nickel–titanium

Naval Ordnance Laboratory) [2, 3]. Buehler’s original task was finding a metal with a high

melting point and high impact resistant properties for the nose cone of the Navy’s missile

SUBROC. From among sixty compounds, Buehler selected twelve candidates to measure their

impact resistance by hitting them with hammer. He noted that a nickel–titanium alloy seemed to

exhibit the greatest resistance to impact in addition to satisfactory properties of elasticity,

malleability and fatigue. One day he took some NiTiNOL bars from melting furnace and laid

them out on a table to cool. He intentionally dropped one on the floor out of curiosity. The bar

produced a bell–like quality sound. Than he ran to the fountain with cold water and chilled the

warm bar. The bar was once again dropped on the floor. On his amazement it exhibited the

leaden–like acoustic response. Buehler knew that acoustic damping signalled a change in atomic

structure that can be turned off and on by simple heating and cooling near room temperature, but

he did not yet know that this rearrangement in the atomic structure would lead to shape memory

effect [3, 6].

It was in 1960 when Raymond Wiley joined Buehler’s research group. He worked on failure

analysis of various metals. He demonstrated to his management the fatigue resistance of a

NiTiNOL wire by flexing it. The directors who were present at this meeting passed the strip

around the table, repeatedly flexing and unflexing it and were impressed with how well it held

up. One of them, David Muzzey, decided to see how it would behave under heat. He was a pipe

smoker, so he held the compressed NiTiNOL strip in the flame of his lighter. To the great

amazement of all, it has stretched out completely. When Buehler heard about that, he realized

that it had to be related to the acoustic behaviour he had noted earlier [3, 6]. After this moment,

NiTi alloys increased interest of developing applications based on a shape memory alloys.

3. Definition of a Shape Memory Alloy

Shape memory alloys are a unique class of metal alloys that can recover apparent permanent

strains when they are heated above a certain temperature. The shape memory alloys have two

stable phases - the high–temperature phase, called austenite (named after English metallurgist



William Chandler Austen [3]) and the low–temperature phase, called martensite (named after

German metallographer Adolf Martens [3]).

Figure 1: Different phases of a shape memory alloy [8].

The key characteristic of all shape memory alloys is the occurrence of a martensitic phase

transformation which is a phase change between two solid phases and involves rearrangement of

atoms within the crystal lattice. The martensitic transformation is associated with an inelastic

deformation of the crystal lattice with no diffusive process involved. The phase transformation

results from a cooperative and collective motion of atoms on distances smaller than the lattice

parameters. Martensite plates can grow at speeds which approach that of sound in the metal (up

to 1100m/s). Together with fact, that martensitic transformation can occur at low temperatures

where atomic mobility may be very small, results in the absence of diffusion in the martensitic

transformation within the time scale of transformation. The absence of diffusion makes the

martensitic phase transformation almost instantaneous (a first-order transition). When a shape

memory alloy undergoes a martensitic phase transformation, it transforms from its high–

symmetry (usually cubic) austenitic phase to a low symmetry martensitic phase (highly twinned

monoclinic structure). NiTiNOL’s high temperature phase has B2 crystal structure and its low

temperature phase has B19’ crystal structure. If one ignores the difference between Ni and Ti

atoms, B2 crystal structure is simply body–centred cubic and B19 has the same symmetry as

hexagonal–close packed, except that the two species of atoms break hexagonal symmetry

making the structure to tetragonal. B19’is a small distortion from B19 [7]. As in Figure 2.



Figure 2: The cubic B2 cell (shaded box) of NiTi (left). The distortion to the stress–stabilized

B19’ structure (right). Structural parameters for B2 structure are a = 2.949 °A, b = 4.171 °A, c =

4.171 °A and = 90_; structural parameters for B19’ structure are a = 2.861 °A, b = 4.600 °A, c =

3.970 °A and = 97.8_ [9]. A feature of all martensitic transformations is that there are number of

equivalent shear directions through which the martensite can form within a region of parent–

phase. This results in the formation of martensite variants within the microstructure of a

transformed alloy. In Figure 1 at twinned martensite phase, we can see two crystallographically

equivalent martensite variants created by different atomic shears from the parent phase. Two

opposite shears maintain the macroscopic shape of the crystal block. Such a microstructure,

where the shear of one variant is accommodated or “cancelled” by that of the other, is know as a

self–accommodated structure. Three–dimensional self–accommodation requires a large number

of variants (typically up to 48 in many alloys) [5]. Upon cooling without of applied load the

material transforms from austenite into twinned martensite. With heating twinned martensite, a

reverse martensitic transformation takes place and as a result the material transforms to austenite.

This process is shown in Figure 3. There are four critical temperatures defined. Martensitic start

temperature (Ms) which is the temperature at which the material starts transforming from

austenite to martensite. Second is martensitic finish temperature (Mf ), at which the

transformation is complete and material becomes fully in the martensitic phase. Similar

temperatures are defined for reversible transformation. Austenite start temperature (As) is the

temperature at which the reverse transformation starts and austenite finish temperature (Af ) at

which the reverse transformation is finished and the material is in the austenitic phase.



Figure 3: Temperature–induced phase transformation of a shape memory alloy without mechanical Loading [8].

4. Engineering Effects of SMAs

Having introduced the key properties of a shape memory alloy, it is now possible to review two

important behaviors exhibited by such materials. These are the shape memory effect (SME) and

the pseudoelastic effect. The usefulness of SMAs is most commonly found in the application of

one of these two engineering effects, with SME used for actuation and pseudoelasticity

employed for applications such as vibration isolation and dampening. These two behaviors will

now be discussed in more detail. The stability of the material response when considering both

effects will also be reviewed.

4.1 The Shape Memory Effect

Recovery of the seemingly permanent deformation observed during detwinning is associated

with the phenomenon known as the stress-free shape memory effect. The nature of the SME can

be better understood by following the process depicted in the stress-temperature phase diagram,

schematically shown in Figure 4. This loading path is experimentally exemplified in s−e−T space

in Figure 5, which shows an actual loading path for a NiTi wire actuator captured during

experimentation at Texas A&MUniversity. At the start of the loading path (indicated by A in

Figures 4 and 5) the SMA is in its parent austenitic phase. In the absence of applied stress, the



SMA will transform upon cooling into martensite in the twinned or self accommodated

configuration (indicated by B in Figures 4 and 5). As stress is applied causing the martensitic

phase to be reoriented into a fully detwinned state, deformation takes place and large

macroscopic strains are observed (indicated by C in Figures 4 and 5). The magnitude of this

strain is on the order of 8% for some NiTi alloys [12]. Upon unloading, the elastic portion of the

total strain is recovered while the inelastic strain due to the detwinning process remains due to

the stability of detwinned martensite. This point is indicated by D in Figures 4 and 5. Upon

heating the SMA at zero stress, the reverse transformation to the austenitic parent phase begins

when the temperature reaches As (point E), and is completed at temperature Af (point F Figures 2

and 3). The inelastic strain due to reorientation is recovered, and thus the original shape (before

deformation B–C) is regained. Note that, in this case, the formation of any nonrecoverable

plastic strain has been neglected. Therefore, point A is equivalent to point F in terms of the state

of the material. It is this reversion to an original or “remembered” shape that inspired the names

“shape memory alloy.”

Fig:4 Phase diagram schematic highlighting stress-free SME, Fig:5 Experimental stress–strain–temperature curve of a NiTi SMA

illustrating the shape memory effect isobaric SME, and isothermal pseudoelastic loading paths.

Now consider another loading path denoted by −−− − in Figure 4 and also shown

experimentally in Figure 4 [13]. Such a path is similar to the one previously described, though in

this particular case a constant stress is maintained throughout the thermal cycle. This is

exemplified by hanging a weight on an SMA component such as a wire or spring. If the SMA

material begins in austenite (a) and is cooled through transformation into martensite (−), it will

exhibit large strains associated with the phase transformation. Such strains are the result of both



the alteration of the crystal structure from austenite to detwinned martensite as well as the

change in the elastic modulus during phase change. However, this elastic contribution is minor.

Heating the material through the reverse transformation region (−) leads to reversion to

austenite and subsequent recovery of the large macroscopic strains, with the exception of any

non-recoverable plastic strains. Such plastic strains can be observed at the end of heating in

Figure 4. Because the recovered strain is used to provide displacement under a some force, it is

also sometimes referred to as the actuation strain (act

). Note that this shape recovery will cease

to occur if the applied stress exceeds some maximum level. This characteristic maximum

actuation stress is often referred to as the blocking stress and can be easily experimentally

determined.

4.2 The Pseudoelastic Effect

A second commonly utilized phenomenon observed in SMAs is the pseudoelastic effect.

This behavior is associated with stress-induced detwinned martensite (SIM) and subsequent

reversal to austenite upon unloading. The transformation from austenite to detwinned martensite

during pseudoelastic loading is analogous to the reorientation of twinned martensite into

detwinned martensite during detwinning from the point of view that, in both cases, recoverable

inelastic strains are created. However, in the case of the pseudoelastic effect, the starting phase is

austenite, and there is an actual phase transformation that takes place under the influence of

stress. An isothermal pseudoelastic loading path in the stress-temperature space is schematically

shown in Figure 5. Note that any load path which includes formation of SIMand begins and ends

in the austenitic region results in the pseudoelastic effect. Initially, the material is in the

austenitic phase (point 1 in Figures 6 and 7). The simultaneous transformation and detwinning of

the martensite starts at point 2 and results in fully transformed and detwinnedmartensite (point

3). Continued loading will lead to elastic deformation of the detwinned martensite. Upon

unloading, the reverse transformation starts when point 4 is reached. By the end of the unloading

plateau (point 5), the material is again in the austenitic phase and upon unloading to zero stress

all elastic strain (el ) and transformation strain (t ) is recovered. Only plastic strain (

p), if

generated, remains. A typical experimental result generated at Texas A&M and showing the

pseudoelastic response of a NiTi SMA is presented in Figure 5. Here the temperature was

maintained at a constant 80_C. For stresses below sMs the SMA responds elastically. When the

polycrystalline SMA critical stress (sMs) is reached, (AMdt

) transformation initiates and SIM



begins to form. During the transformation into SIM, large inelastic strains are generated (upper

plateau of stress-strain curve in Figure 7). This transformation completes when the applied stress

reaches a critical value, sMf . The material is now in a detwinned martensitic state. For further

loading above sMf thematerial responds nearly elastically. Upon unloading, which is initially

elastic, the reverse transformation initiates at a critical stress, sAs, and completes at a stress sA f

because the mechanical load is applied at a temperature above Af . Note that, due to the positive

slopes of the four transformation lines in the phase diagram, increasing the test temperature

results in an increase in the value of each critical transformation stress. A hysteretic loop is

obtained in the loading/unloading stressstrain diagram. If the applied stress exceeds the critical

value sMf , then the width of the hysteresis loop, less any accumulated non-recoverable plastic

strain, is representative of themaximum amount of recoverable strain which can be produced due

to stress-induced phase transformation from austenite to martensite (et ). Another important

material characteristic observed in Figure 7 is the residual plastic strain (epl ) of _ 0.6% seen

remaining at the end of the loading cycle.

Fig 6: Experimental results illustrating the SME under a constant 200MPa stress (NiTi, [13]).



5. Applications for Shape Memory alloys

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

super-elasticity. 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.

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. 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


Submitted By- TARINI PRASAD MISHRA

Hall Ticket No- 08261A1856, 4th Year, MME

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.

Piping: The first consumer commercial application for the material was as a shape-memory

coupling for piping, e.g. oil line pipes for industrial applications, water pipes and similar types of

piping for consumer/commercial applications.

Automotive: The first high volume product (> 5Mio actuators / annual) is an automotive valve

application build to run low pressure pneumatics /bladders in a car seat to adjust the contour

(lumbar support / bolsters). The accounting of basical all benefits of SMA over solenoids

(noise/EMC/weight/package (form factor)/power consumption) was the crucial factor to replace

the standard technology by SMA. Where in other applications usually just 2 or 3 SMA benefits

are considered and hinder from replacing the 'old' technologies.

Robotics: There have also been limited studies on using these materials in robotics, for example

the hobbyist robot Stiquito (and "Roboterfrau Lara"), as they make it possible to create very light

robots. Weak points of the technology are energy inefficiency, slow response times, and

large hysteresis.

6. Advantages of Shape Memory Alloys

As reviewed above, shapememory alloys are capable of providing unique and useful behaviors.

The shape memory effect, especially when utilized under applied stress, provides actuation. The

pseudoelastic effect provides two very useful advantages to the aerospace designer: a non-

http://en.wikipedia.org/wiki/Stiquito




linearity which allows vibration isolation and large recoverable deformations as well as an ac-

companying hysteresis which can dissipate energy and therefore dampen vibration. Because of

these, shape memory alloys can provide a highly innovative method of addressing a given design

problem and are often the only viable option. When considering actuation, a single SMA

component represents a significantly more simplified solution than a standard electromechanical

or hydraulic actuator. Compared to other classes of active materials, SMAs are able to provide

substantial actuation stress over large strains. The subsequent high energy density leads to

compact designs. Finally, SMAs are capable of actuating in a fully three-dimensionalmanner,

allowing the fabrication of actuation components which extend, bend, twist, or provide a

combination of these and other deformations. Each of the actuation application examples listed

above exploit one or more of these positive attributes of SMA behavior. Some require simplicity

and resulting reliability (Mars Pathfinder [17], LFSA [14]). Others require compact actuation

(active skin [13], micro space actuation [17]), and still others impose geometric challenges

(active chevrons [24], rotor blade actuation [26]). Because of their unique properties, SMAs are

able to provide solutions to each of these sets of problems. The SMA design process is not

without some challenges, however, and several material attributes must be carefully considered.

One common design challenge is the difficulty in rapidly transferring heat into and especially out

of an SMA component. This is a result of the fact that, as a metallic material, SMAs have a

relatively high heat capacity and density. When considering repeated actuation of SMA

elements, for example, this heat transfer difficulty leads to a limited frequency of system

response. Although the material mechanisms involved in the diffusionless phase transformation

can occur almost instantaneously, the timedependent process of sufficiently changing

temperature to drive that transformation can limit actuation speed. Moreover, while the supply of

thermal energy can be quickly accomplished (e.g. by direct Joule heating via application of

electricity), the speed of energy removal is limited by the mechanisms of heat conduction and

convection. Several methods have been employed in the hopes of expediting heat transfer,

including forced convection via flowing cooled water [19] and forced conduction through the use

of thermoelectric cooling modules [12]. A second challenge is the low actuation efficiency.

Efficiencies can reach levels in the range of 10%–15% [18] though in some studies they have

fallen short of the idealistic Carnot predictions of _ 10% [24,25]. This is often not important for

commercial and military aircraft applications because engine power and waste heat are often in




excess. However, this property can present a significant challenge to those proposing SMA use

on spacecraft, where power is more limited. Finally, there are challenges stemming from the

response of an SMA material when subjected to multiple transformation cycles. If a low number

of cycles is required, the issue is material stability. For consistent multi-cyclic actuation, SMA

elements which have developed a sufficiently stable thermomechanical response via repeated

training cycles should be used. SMA components which are not completely trained yet are

repeatedly transformed will lead to system responses which evolve with every cycle. However, if

a device is intended for one-time operation, such as a micro-actuator for satellite use, then

training is not necessary. Designers must also consider the possible degradation of material

response due to the generation of TRIP, especially when considering many actuation cycles. The

topic of SMA fatigue has been discussed in the literature [4,72,73]. For the first 10–100 cycles,

thematerialwill stabilize, as previously discussed. As with all other metals, however, repeated

deformation of sufficientmagnitudewill eventually lead to failure. Experimental studies on NiTi

or NiTiCu SMA wires undergoing up to 2% transformation strain have shown that such SMA

components can survive for _10,000 cycles [4]. This implies a limitation on the number of cycles

an SMA application can provide.

7. Conclusion

Considering the variety of research and development currently being performed in the area of

shape memory alloys, it is clear that new applications will continue to be developed and that this

field will continue to grow. The needs of various defense agencies will continue to present

greater challenges to engineers and designers. The complexity of space operations is ever

increasing and more is demanded of aircraft, both commercial and military, thus more innovative

technological solutions will be required. The fields of SMA research and application are

providing the tools to meet these challenges. The ability to custom order SMA material with

particular properties manufactured to prescribed specifications has improved. The design and

analysis environments are becoming more powerful by becoming more comprehensive. At the

same time, systems integration capabilities have grown. These developments will result in an

increased prevalence of integrated multifunctional SMA systems for aerospace applications.

Such systems will be highly beneficial to the design of new UAVs and micro- and nano-




satellites. Other industries will also benefit from the advances made in the SMA field. The

automotive and and oil exploration sectors, each of which has already shown increasing interest,

will continue to employ the properties of SMAs in solving design problems where constraints are

imposed by extreme environments and operating conditions. It is widely expected that medical

applications will further increase in number. This overall growth in the utilization of

shapememory alloys and other activematerials will provide designers with more options, and

those in the aerospace industry should continue to take advantage of the unique engineering

solutions provided by shape memory alloys.




REFERENCES

[1] K. Otsuka, C. M. Wayman (Eds.), Shape Memory Materials, Cambridge University Press,

Cambridge, 1999.

[2] A. V. Srinivasan, D. Michael McFarland, Smart Structures: Analysis and Design, Cambridge

University Press, 2000.

[3] T. Duerig, K. Melton, D. Stockel, C. Wayman (Eds.), Engineering Aspects of Shape Memory

Alloys, Butterworth- Heinemann, London, 1990.

[4] E. Patoor, D. C. Lagoudas, P. B. Entchev, L. C. Brinson, X. Gao, Shape memory alloys, Part

I: General properties and modeling of single crystals, Mechanics of Materials 38 (5–6) (2006)

391–429.

[5] D. C. Lagoudas, P. B. Entchev, P. Popov, E. Patoor, L. C. Brinson, X. Gao, Shape memory

alloys, Part II: Modeling of polycrystals, Mechanics of Materials 38 (5–6) (2006) 430–462.

[6] M. A. Qidwai, D. C. Lagoudas, Numerical implementation of a shape memory alloy

thermomechanical constitutive model using return mapping algorithms, International Journal for

Numerical Methods in Engineering 47 (2000) 1123–1168.

[7] D. C. Lagoudas, Z. Bo, M. A. Qidwai, A unified thermodynamic constitutive model for SMA

and finite element analysis of active metal matrix composites,Mechanics of Composite Materials

and Structures 3 (1996) 153–179.

[8] L. C. Brinson, One-dimensional constitutive behavior of shape memory alloys:

Thermomechanical derivation with non-constant material functions and redefined martensite

internal variable, Journal of Intelligent Material Systems and Structures 4 (1993) 229–242.

[9] S. Leclercq, C. Lexcellent, A general macroscopic description of the thermomechanical

behavior of shape memory alloys, JMPS 44 (6) (1996) 953–980.

[10] P. Popov, D. C. Lagoudas, A 3-D constitutive model for shape memory alloys incorporating

pseudoelasticity and detwinning of self-accommodatedmartensite, Submitted to the International

Journal of Plasticity .

[11] M. A. Qidwai, D. C. Lagoudas, On the thermodynamics and transformation surfaces of

polycrystalline NiTi shape memory alloy material, International Journal of Plasticity

16 (2000) 1309–1343. [12] J. Perkins, ShapeMemory Effects in Alloys, Plenum Press, 1975.




[13] D. A. Miller, D. C. Lagoudas, Thermo-mechanical characterization of NiTiCu and NiTi

SMA actuators: Influence of plastic strains, Smart Materials and Structures 9 (5) (2000) 640–

652.

[14] Z. Bo, D. C. Lagoudas, Thermomechanical modeling of polycrystalline SMAs under cyclic

loading, Part III: Evolution of plastic strains and two-way shapememory effect, International

Journal of Engineering Science 37 (1999) 1175– 1203.

[15] D. Lagoudas, P. Entchev, Modeling of transformationinduced plasticity and its effect on the

behavior of porous shape memory alloys: Part I: Constitutive model for fully dense SMAs,

Mechanics of Materials 36 (2004) 865–892.

[16] D. Hartl, B. Volk, D. C. Lagoudas, F. T. Calkins, J.Mabe, Thermomechanical

characterization and modeling of Ni60Ti40 SMA for actuated chevrons, in: Proceedings of

ASME, International Mechanical Engineering Congress and Exposition (IMECE), 5–10

November, Chicago, IL, 2006, pp. 1–10.

[17] E. Renner, Thermal engine, U.S. Patent 3,937,019 (1976).

[18] K. R. Melton, General applications of shape memory alloys and smart materials, in: K.

Otsuka, C. M. Wayman (Eds.), Shape Memory Materials, Cambridge University Press,

Cambridge, 1999, Ch. 10, pp. 220–239.

[19] E. Garcia, Smart structures and actuators: Past, present, and future, Proceedings of SPIE,

Smart Structures and Materials, San Diego, CA, 17–21 March (2002) 1–12.

[20] B. Sanders, R. Crowe, E. Garcia, Defense advanced research projects agency – Smart

materials and structures demonstration program overview, Journal of Intelligent Material

Systems and Structures 15 (2004) 227–233.

[21] J. Kudva, Overview of the DARPA smart wing project, Journal of Intelligent Material

Systems and Structures 15 (2004) 261–267.

[22] J. Kudva, K. Appa, C. Martin, A. Jardine, Design, fabrication, and testing of the

DARPA/Wright lab ‘smart wing’ wind tunnel model, in: Proceedings of the 38th

AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, andMaterials Conference and

Exhibit, Kissimmee, FL, 1997, pp. 1–6.

[23] P. Jardine, J. Kudva, C. Martin, K. Appa, Shape memory alloy NiTi actuators for twist

control of smart designs, in: Proceedings of SPIE Smart Materials and Structures, Vol. 2717, San

Diego, CA, 1996, pp. 160–165.




[24] P. Jardine, J. Flanigan, C. Martin, Smart wing shape memory alloy actuator design and

performance, in: Proceedings of SPIE, Smart Structures and Materials, Vol. 3044, San Diego,

CA, 1997, pp. 48–55.

[25] D. Pitt, J. Dunne, E. White, E. Garcia, SAMPSON smart inlet SMA powered adaptive lip

design and static test, Proceedings of the 42nd AIAA Structures, Structrual Dynamics, and

Materials Conference, Seattle, WA, 16–20 April 2001 .

[26] N. Reya, G. Tillmana, R. Millera, T.Wynoskyb,M. Larkin, Shape memory alloy actuation

for a variable area fan nozzle, in: Proceedings of SPIE, Smart Structures and Materials, Vol.

4332, Newport Beach, CA, 2001, pp. 371–382.

[27] J. Mabe, R. Cabell, G. Butler, Design and control of a morphing chevron for takeoff and

cruise noise reduction, in: Proceedings of the 26th Annual AIAA Aeroacoustics Conference,

Monterey, CA, 2005, pp. 1–15.

[28] J. H.Mabe, F. Calkins, G. Butler, Boeing’s variable geometry chevron, morphing

aerostructure for jet noise reduction, in: 47th AIAA/ ASME / ASCE / AHS / ASC Structures,

Structural Dynamics and Materials Conference, Newport, Rhode Island, 2006, pp. 1–19.

Technical Seminar Report

Documents

Transcript of Technical Seminar Report