impact of smart materials in aero industry - bonfring · there are number of types of smart...

International Conference on Challenges and Opportunities in Mechanical Engineering, Industrial Engineering and Management Studies 440

(ICCOMIM - 2012), 11-13 July, 2012

ISBN 978-93-82338-04-8 | © 2012 Bonfring

Abstract--- Materials have a strong relationship with aerospace industry, as it always determines the weight,

strenght, efficiency, cost and difficulty of maintainance of an aircraft. Therefore, the discovery of new material

usually makes a break through in performance of an aircraft. Especially the findings of smart material, makes an

innovation in aircraft because it can provide a special function or property . Accordingly, the smart materials

receive a great attention inorder to improve the performance of aircraft.

Keywords--- Smart Wing, Aircraft Tyres, Helicopter Blades

I. INTRODUCTION

MART materials or designed materials are materials that have one or more properties that can be significantly

changed in a controlled fashion by external stimuli such as stress, temperature, moisture, pH, electric or

magnetic fields. There are number of types of smart materials some of which are already common. Some examples

are piezoelectric material, shape memory alloys, chromogenic systems etc. Studying of the smart materials is a key

to make the innovation of aerospace industry. The reason is the conventional automatic system has several

limitations comparing to the smat system. Therefore,studying smart material is necessary for improving aircraft‟s

performance.

II. WHAT ARE SMART MATERIALS?

Smart materials are the materials that have the property that can be significantly changed in a controlled fashion

by external stimuli, such as, stress, temperature, moisture, pH, electric or magnetic fields. Science and technology

have made amazing developments in the design of electronics and machinery using standard materials, which do not

have particularly special properties (i.e. steel, aluminum, gold). Imagine the range of possibilities, which exist for

special materials that have properties scientists can manipulate. Some such materials have the ability to change

shape or size simply by adding a little bit of heat, or to change from a liquid to a solid almost instantly when near a

magnet; these materials are called smart materials.

Figure 1

Jincy Philip, Student, Sathyabama University, Chennai. E-mail: [email protected]

Litty John, Student, Sathyabama University, Chennai. E-mail: [email protected]

PAPER ID: MEP36

Impact of Smart Materials in Aero Industry

Jincy Philip and Litty John

S

mailto:[email protected]

mailto:[email protected]


(ICCOMIM - 2012), 11-13 July, 2012

ISBN 978-93-82338-04-8 | © 2012 Bonfring

2.1. Different Types of Smart Materials

Piezo Electric Material: which produces voltage when stress is produced.

Shape Memory Alloys: which large deformation can be induced and recovered through temperature changes

or stress changes.

Thermo Electric Material: are used to build devices that convert temperature differences into electricity and

vice-versa.

Photomechanical Material: change shape under exposure to light.

III. PIEZO ELECTRIC MATERIAL

The classic definition of piezoelectricity is the generation of electricity polarization in a material due to the

mechanical stress. It is called as direct effect. The piezoelectric material has a converse effect that a mechanical

deformation will happen if an electrical charge or signal is applied. Accordingly, it can be a sensor to detect the

mechanical stress by direct effect. Alternatively, a significant increase of size due to the electrical charge can be an

actuator. Piezoelectric materials have two unique properties which are inter related.

Figure2

When a Piezo electric material is deformed it produces electricity in small but measurable. Alternately, when an

electrical is deformed, it gives off a electrical discharge current is passed through a piezoelectric material it

experiences a significant increase in size (up to a 4% change in volume) (as shown in the figure2). The property that

can be altered influences what types of applications the smart material can be used for.

3.1. Properties of Piezo Electric Material

Among different types of smart material, piezoelectric material is widely used because of the fast

electromechanical response, wide bandwidth, high generative force and relatively low power requirements. There

are two main types of piezoelectric materials that are applied as smart materials, which are piezoelectric ceramic and

polymer. The piezoelectric material has a converse effect that a mechanical deformation will happen if an electrical

charge or signal is applied. Accordingly, it can be a sensor to detect the mechanical stress by direct effect.

Alternatively, a significant increase of size due to the electric charge can be actuator.

3.2. Theorem Of Piezo Electric Material

Basically, piezoelectric material is a transducer between electricity and mechanical stress.[1]

.The Piezo electrical

material has this effect because of its crystalline structure. For the crystal, each molecule has a polarization; it means

one end is more negatively charged while the other end is more positively charged, and it is called dipole.

Furthermore, it directly affects how the atoms make up the molecule and how the molecules are shaped.

Therefore, the basic concept of piezoelectricity is to change the orientation of polarization of the molecules.


(ICCOMIM - 2012), 11-13 July, 2012

ISBN 978-93-82338-04-8 | © 2012 Bonfring

Figure 3

IV. ROLE OF PEIZO ELECTRIC MATERIAL IN AERO INDUSTRY

Aerospace manufacturers face extreme pressure to lower costs, while increasing performance and satisfying

stringent safety standards. Producers in the commercial airline, defense and space exploration sectors continually

seek new materials that are reliable and robust, and meet the needs of highly specialized applications.. The two

important Piezo electric materials are piezoelectric ceramic and polymer.

Advanced ceramics, such as Alumina, Silicon Nitride and Aluminum Nitride are currently being used to

manufacture critical aerospace components, because they have several advantageous physical properties. These

inorganic, non-metallic materials retain dimensional stability through a range of high temperatures and exhibit very

high mechanical strength. They also demonstrate excellent chemical resistance and stiffness-to-weight ratio, thereby

providing manufacturers with the ability to design Components that offer optimal performance in their intended

application.

4.1. Instrumentation and Control System

Electro ceramic materials (piezoelectric and dielectric) are used in aerospace transducers and sensors such as

accelerometers (for measurement of vibration), gyroscopes (for measurement of the acceleration and pitch of

aircraft, missiles and satellites) and level sensors (e.g. fuel tanks). One of the most successful commercial aircrafts in

recent times, the Boeing 777, uses Piezo ceramic material [6]

within the 60 ultrasonic fuel tank probes located on

each aircraft. The ultrasonic transducers are installed at a variety of locations in each fuel tank. A pulsed electric

field is applied to the Piezo ceramic material, which then responds by oscillating. The resulting sound waves are

reflected off the surface of the fuel and picked up by the Piezo-electric ceramic transducer. A digital signal processor

interprets the „time of flight‟ measurement of the sound waves in order to continually indicate the amount of fuel

present. Similar ultrasonic fuel probes are also used in fighter aircraft and other level sensing applications because of

their ability to provide highly accurate readings, regardless of the orientation of the aircraft.

4.2. Seals and Thermocouples

Advanced ceramics are also ideally suited for aerospace [7]

applications that provide a physical interface between

different components, due to their ability to withstand the high temperatures, vibration and mechanical shock

typically found in aircraft engines and other high stress locations. Ceramics are commonly found in seals for gas

turbine engines, fuel line assembly, and thermocouples. Where ceramic/metal assemblies are required, joining the

two materials generally involves metalizing the ceramic surface and then brazing the components together.

4.3. Aero Engine Component Repair

Research into the development of advanced brazing materials for aero engine component repair has also led to

the development of brazing materials ideal for the repair of gas turbine engine components. One example is the use

of pre-sintered performs (PSP) for high temperature brazes repair applications. With turbine temperatures reaching

up to 1300ºC (2350ºF) and the presence of hot corrosive gases, components experience considerable erosion and

wear.

The pre-sintered performs consist of a blend of super alloy and low melting point braze and are customized to fit

the shape of the component and then tack-welded into place and brazed. The ability to provide a range of near net


(ICCOMIM - 2012), 11-13 July, 2012

ISBN 978-93-82338-04-8 | © 2012 Bonfring

thicknesses can eliminate the need for most post-braze machining and extend the life of engine components by up to

300 percent, making it a more reliable and cost effective method than traditional welding which requires post-braze

machining or grinding.

4.4. Ion Propulsion

Ion propulsion technology, which uses electricity to charge heavy gas atoms that accelerate from the spacecraft

at high velocity and push it forwards, traditionally incorporated quartz discharge vessels. Quartz has now been

replaced by Alumina because of the need for a material with the same dielectric properties but with higher structural

stability. Alumina is easier to fabricate and offers good thermal shock resistance, ensuring that the chamber can

withstand the extremes of temperature that occur during plasma ignition. It is also lighter, which reduces the costs

associated with each launch.

4.5. Aerodynamic Feature

In term of shape changing, it means the changing of aerodynamic feature. Conventionally, the aircrafts‟ control

surface is still controlled indirectly and lack of flexibility. However, the piezoelectric actuator can perform an

innovative mechanism of control system; it greatly increases the performance and maneuverability due to flexible,

efficient and thin actuator.

4.6. Vibration Control

Regarding vibration, it is an unwanted effect in aircraft because it can contribute to stress concentration, material

fatigue, shortening service life, efficiency reduction and noise. Obviously, these problems influence the safety and maintenance

cost sharply. Besides, the noise problem is always considered, especially the passengers‟ aircraft, as the noise is a great

annoyance.

Figure 4

Therefore, the engineers always want to minimize the vibration. Conventionally, it is difficult to provide a

precise active damping which produces a vibration with anti-resonance frequency. By the piezoelectric material, it

can be used as sensor and actuator at the same time, so it has a fast enough response to produce the anti resonance

vibration [8]

(Fig4). Furthermore, it is flexible, small and thin to be applied in many parts of aircraft.

4.7. Cabin Interior Noise

The noise of aircraft is a significant annoyance to the passengers. Conventionally, the passive damping device is

used which is just capable of high frequency vibration. However, the interior noise from vibration of fuselage and

engine is low frequency hence the passive damping device cannot perform a satisfied noise reduction. Accordingly,

an active damping device is needed and the piezoelectric material is suitable choice.

Basically, this noise reduction system is called Active Structural Acoustic Control (ASAC). In this system, the

piezoceramic patch actuators are used with passive vibration insulations to optimize the capabilities (Manner HP &

Wierach P). The Bombardier Dash-8 turbo prop aircraft was used as the test model and the result is satisfied (Figure

5). There was a reduction more than 20dB at the blade passage frequency of 61Hz.


(ICCOMIM - 2012), 11-13 July, 2012

ISBN 978-93-82338-04-8 | © 2012 Bonfring

Figure 5

4.8. Ceramic Heat Shields and Windscreens

Ceramic fibers are used as heat shields for fire protection and thermal insulation in aircraft and space shuttles

because they resist heat, are lightweight and do not corrode. Other significant characteristics include high melting

temperatures, resiliency, tensile strength and a chemical inertness. In addition, aircraft windshields are heated by a

transparent, electric-conducting ceramic coating embedded in the glass to keep them clear from fog and ice.

4.9. Smart Materials to Design a Smart Wing

A conventional aircraft wing uses hydraulics and an electronic motor to move the flaps into their proper positions

for ascent and descent, so it is very heavy and noisy. By replacing those with these „smart materials‟ [2]

that we can

manipulate through applied heat using electrical current. When electricity is applied, it heat the spring on the bottom

that will contract and pull the flap down. So it eliminated the need for a hydraulic and motor system within the

aircraft‟s wing, because the current would be provided by a power supply already located within the aircraft. Many

structures are available for this (fig6).

Figure 6

4.10. Use of Piezoelectric Material in Aircraft Tyres

Piezoelectric materials like Quartz are used for producing electricity [4]

. Piezoelectric cell are mounded at the

places where mechanical strain is produced. These piezoelectric cells can be mounted inside the tyres of aircraft

(figure7) to generate electricity and used in most efficient way. During takeoff and landing of aircraft the pressure

exerted on the Quartz plates are considered. The pressure exerted is far below the sustainability of plates. Hence can

be used for production of electricity.

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(ICCOMIM - 2012), 11-13 July, 2012

ISBN 978-93-82338-04-8 | © 2012 Bonfring

Figure 7

4.11. Energy Saving Helicopter Blades

Helicopters can Perform some incredible aerobatic feats. But they are also noisy, shaky and expensive to run.

Figure 8

Researches‟ are developing helicopter blades featuring shape-shifting smart materials that could lead to a

smoother, quieter more fuel efficient ride. The blades used are piezoelectric actuators [11]

mechanical devices

incorporating a material that change a shape when subjected to an electrical field.

As a helicopter blade passes to air, smart materials attached in blade (see fig8) leaves behind a wake, and as the

blade behind it passes through that wake it experiences a periodic vibration. Having blade actuation [6]

allows you to

put a periodic motion into the blade flaps with a right amplitude, phase and frequency to cancel out that vibration.

V. FUTURE OF SMART MATERIALS

The enabling advantages of Smart materials utilization often outweigh the challenges, and because of this, the

future of this field is promising. As more applications across all industry sectors are designed and put into use. The

Smart materials market will continue to grow and the cost of the material will continue to fall. At the same time the

quality of material produced will increase.

Considering the variety of research and development currently being performed in the area of smart materials, it

is clear that new application will continue to be developed and that this field will grow. The overall growth in the

utilization of Smart materials will provide designers with more options, and those in the aero industry should

continue to take advantage of the unique engineering solutions provided by Smart materials.

VI. CONCLUSION

In the studying of smart materials, their properties in response to external condition such as temperature, stress,

electrical charge, magnetic field, are understood and these unique properties receive a great attention from airspace

industry. The reason is that properties can be applied to different parts in the aircraft to improve the overall

performance. For eg. By using the smart material actuator, its performance is much more efficient than the

conventional system since the electricity is directly conversed to actuation, number of parts is greatly reduced and

transmitting speed of electricity is much higher. Moreover, an innovative research is experiencing to make the

adaptive wing or control surfaces which can greatly increase the maneuverability. In addition smart material is


(ICCOMIM - 2012), 11-13 July, 2012

ISBN 978-93-82338-04-8 | © 2012 Bonfring

usually light in weight and can be made in the compact size. At the same time, cost can be reduced and maintenance

can be minimized by using vibration control smart material. By using piezoelectric material in helicopter blade we

can reduce the noise that‟s created during the flight. Therefore the smart materials represent the innovation of

aerospace industry and they are believed to be widely used in the future.

REFERENCES

[1] Zhong Lin Wang & Z.C.Kang, “Function and Smart Materials Structural Evolution& Structural Analysis”,

1998.

[2] Yousefi-koma, A & Zimick, Application of smart structures to aircraft for the performance enhancement,

Canadian Aeronautics and space journal, volume 49,no4,2003.

[3] Hartal, Dj&Lanonds, Journal of aerospace engineering, 2007, volume221, issue4, p535-552.

[4] Joshi, Application of Magnetic Smart Materials, 1999.

[5] Hariz, smart materials, structures and integrated system, SPIE-the international society of optical engineering,

1999.

[6] Le-letty, claeyreren f, Amplified Piezo Electric ceramic Actuation for Aero Space Application, Cedrat

Technologies, SA.

[7] Joshi, C & Bent, Application of Magnetic Smart Materials to Aerospace Motion Control. 1999.

[8] Giyrgiutiu, Recent advances in smart-material rotor control actuation, University of South Carolina. V 2000.

[9] The piezoelectric effect, Radio Education and Research Center 2007.

[10] Joshi, C, Bent, B, Drury, M, Preble, J & Nguyen, „High Force‟, Precision Positioning Using Magnetic Smart

Materials. 19.

[11] Newton, David V, Main, John A, Garcia, Ephraim, Massengill, Lloyd; “Piezoelectric actuation systems:

optimization of driving electronics”, Proc. SPIE Vol. 2717, p. 259-266.

[12] C.Nam, Yakima, Application of smart materials for aircraft maneuver enhancement, volume4701,pp 226-236.

impact of smart materials in aero industry - bonfring · there are number of types of smart...

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