Advanced Active Materials

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Advanced Materials

Human Powered Aircraft Group


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Advanced Materials

Advanced materials areused in aircraft design

to:-Reduce weight

-Improve strength

-Design morphing wings

-Create self-healingstructures


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Examples of Advanced Materials

Memory Polymers Composites

Biocomposites ThermoplasticsAlloys


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Memory Polymers: Veriflex andVeritex

Veriflex is a shape memory polymer resin whichmodifies its shape in response to temperaturechanges.

Veritex is a dynamic composite that utilizesVeriflex resin as its matrix. When heated, Veritexis pliable and maintains shape as it cools,regaining structural stiffness. Once reheated it

returns to its original shape and can beremolded without degrading.

Future polymers may respond to light, electricfields and magnetic fields.


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Composites

Composites are a combination of two ormore organic or inorganic components

one of which serves as a matrix holdingthe materials together and then other ofwhich serves as reinforcement in the formof fibers

Composites are lightweight and strong butthey are complex to manufacture,expensive and hard to inspect for flaws


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Thermoplastics

Thermoplastics are a new type ofmaterials that is replacing thermosets such

as epoxy, bismaleimide, or polyimide, asthe matrix for composites

Thermoplastics are easier to produce and

are much more durable and tougher thanthermosets


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Biocomposites

Biocomposites combine plant fibers with resins to createnatural based composite materials.

High tensile plant fibers including, kenaf, industrialhemp, and flax, can be combined with traditional resinsto create an alternative to traditionally steel or fiberglassapplications.

Some advantages over traditional composites: Reduced weight Increased flexibility

Greater moldability Less expensive Sound insulation Renewable resource Self-healing properties


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Alloys

Benefits of Alloys: Decreased weight

Durable Easy to manufacture and repair


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Application to Morphing Wings

Stronger, shape memory and self-healingpolymers are applicable to the design ofmorphing wings Lockheeds 14ft remote-control aircraft makes use of

Veriflex and Veritex polymers to change shape andensure a streamline profile as the wings morph.

Nextgen Aeronautics tested a wing that's structure of

aluminum lattices expanded and compressedconsequently stretching and shrinking the wingssilicone-rubber skin and causing the wing tips tomove forward and back, and changing the wing spanand chord.


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Future development of Personal Air Vehicles(PAV), calls for safer, easy to fly planes.

Self-healing (often biocomposite) materialscan be utilized to reduce maintenance.

An Aeronautic Vehicle Integrated HealthManagement System is looking into self-healing materials that will fill cracks in thestructure by breaking capsules and releasingadhesive.


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Aeronautical Integrated VehicleHealth Monitoring System (IVHM)

Detection of damaging events Characterization of the damage

Prioritization of the seriousness of thedamage

Identification of the cause of the damage

Formulation of the response Execution of the response


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Intelligent sensing system Detects and measures quantities and uses this

information to make forward looking decisions

Uses thousands and perhaps millions ofdifferent sensors used to measure different

quantities (stress, strain, temperature,acoustics, etc)

What is IVHM?


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How Does IVHM work?

Separates structures (skin, ribs,components, etc...) into a series of cells

Each cell is equipped with a group ofsensors

The sensors communicate with

neighboring cells as well as a centralcomputer.


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Types of Sensors

Fiber Optic Piezoelectric

Infrared imaging


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Fiber Optic Sensors

Can measure strain, temperature and pressure Specifically they can measure bond line integrity,

acoustic emissions, and corrosion

Uses Bragg grating to measure changes in light signal A change in stress moves the Bragg grating producing a shift in

the reflected wavelength

Fiber Optics are brittle so they must be embedded into

materials, this is very expensive and complicatesmanufacturing and repair practices.


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Piezoelectric Materials

Convert mechanical input into an electrical signal(sensor) or convert and electrical pulse into a mechanicalaction (actuator)

Can detect energies caused by impact events or defectgeneration (cracks, delamination)

Arrays of sensors allow a pinpoint determination of thedamage location

Sensors have been able to detect cracks 0.005 inches inlength of six inches

Will be embedded or surface mounted. Less expensiveoption


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Infrared Imaging

Detects heat signatures inorder to detect leaks, cracks,debonding, corrosion, poorelectrical wiring and contacts,

and to assess overall thermalprofiles of components.

Most often used to detectdefects or damage in thepropulsion system.

Widely used, inexpensive


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Joint Strike Fighter

Airframe Structures Engine

Electronics Mission Systems Components

Hydraulics Drive Shafts

Fuel system

Electrical system


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Summary of IVHM

Rapidly growing field dependant on the improvementand development of sensing technologies.

It will enable less reliance on statistical based scheduledmaintenance and moves towards a condition basedmaintenance which will greatly reduce ownership costs


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References

http://showcase.netins.net/web/creativecomposites/Biocomposites.html , CreativeComposites, Ltd., 19 September 2006

http://www.crgrp.net/veriflex.htm, CRG Industries, LLC., 19 September 2006 Flying off the Drawing Board, Jeff Wise, Popular Mechanics, volume 183 no. 7, July

2006 http://www.crgindustries.com/veritex.htm, CRG Industries, LLC, 19 September 2006 http://www.centennialofflight.gov/essay/Evolution_of_Technology/composites/Tech4

0.htm, U.S. Centennial of Flight Commission, 23 September 2006

http://ammtiac.alionscience.com/pdf/2004MaterialEASE27.pdf#search=%22Vehicle%20Integrated%20Health%20Monitoring%20System%22, The AMPTIAC Quarterly,

Volume 8, Number 3, Sensors and Sensing Technologies for Integrated VehicleHealth Monitoring Systems
http://showcase.netins.net/web/creativecomposites/Biocomposites.htmlhttp://www.crgrp.net/veriflex.htmhttp://www.crgindustries.com/veritex.htmhttp://www.centennialofflight.gov/essay/Evolution_of_Technology/composites/Tech40.htmhttp://www.centennialofflight.gov/essay/Evolution_of_Technology/composites/Tech40.htmhttp://ammtiac.alionscience.com/pdf/2004MaterialEASE27.pdfhttp://ammtiac.alionscience.com/pdf/2004MaterialEASE27.pdfhttp://ammtiac.alionscience.com/pdf/2004MaterialEASE27.pdfhttp://ammtiac.alionscience.com/pdf/2004MaterialEASE27.pdfhttp://www.centennialofflight.gov/essay/Evolution_of_Technology/composites/Tech40.htmhttp://www.centennialofflight.gov/essay/Evolution_of_Technology/composites/Tech40.htmhttp://www.crgindustries.com/veritex.htmhttp://www.crgrp.net/veriflex.htmhttp://showcase.netins.net/web/creativecomposites/Biocomposites.html

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