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