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Science Technology

Self-Healing System Applied to Aviation 76

ScienceDaily is reporting that the self-healing materials are being used in some new aircraft designs. We covered several self-healing systems in the past months, but it is nice to see it starting to find practical applications. "This simple but ingenious technique, similar to the bruising and bleeding/healing processes we see after we cut ourselves, has been developed by aerospace engineers at Bristol University, with funding from the Engineering and Physical Sciences Research Council (EPSRC). It has potential to be applied wherever fibre-reinforced polymer (FRP) composites are used. These lightweight, high-performance materials are proving increasingly popular not only in aircraft but also in car, wind turbine and even spacecraft manufacture. The new self-repair system could therefore have an impact in all these fields."
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Self-Healing System Applied to Aviation

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  • by clonan ( 64380 ) on Monday May 19, 2008 @01:11PM (#23464286)
    So long as they came with their handy dandy bipedal humanoid repair agents...
    • The new Lockheed L9 CLERIC. It can resurrect itself, but only if it makes that dreaded system shock check...
    • by rcani ( 831229 )

      So long as they came with their handy dandy bipedal humanoid repair agents...
      Make sure you get the bipedal humanoids though, those quadrupedal humanoids are no good...
  • Potential (Score:5, Interesting)

    by Oxy the moron ( 770724 ) on Monday May 19, 2008 @01:14PM (#23464320)

    Since I am far from an expert on the subject... what are the chances this same technology could be applied to prosthetics? If that were doable, I think it'd be an excellent market for allowing people to use prosthetics and be able to do more rigorous physical work.

    Might cut down on the profits of companies that make prosthetics, though, if the things just fix themselves instead of needing to be replaced. :)

  • by ivanmarsh ( 634711 ) on Monday May 19, 2008 @01:14PM (#23464322)
    I for one welcome our flying Terminator overlords.
  • we can kill it.
  • So... (Score:5, Insightful)

    by ZonkerWilliam ( 953437 ) * on Monday May 19, 2008 @01:17PM (#23464360) Journal
    The plane will heal itself after a crash. Great for the plane, not so much for the passengers.
  • Currently (Score:3, Interesting)

    by bostonsoxfan ( 865285 ) on Monday May 19, 2008 @01:17PM (#23464362)
    There are some things already implemented similar to this. At least in concept. Many helicopters are getting new fuel tanks made of special plastics (I'm not really sure) that seal themselves when you shoot a bullet through them so there is little or no leakage. Also there are chromate conversion coatings that allow scratches but over time will repair to be almost like new.
    • Re:Currently (Score:4, Informative)

      by X0563511 ( 793323 ) on Monday May 19, 2008 @02:39PM (#23465312) Homepage Journal
      Previously, we've had self-sealing fuel tanks since WW2. But those had some weird lining that expanded to close the puncture. The important part is preventing burnoff and explosion, not so much leakage. If your venting fuel, you can still (as long as it's not huge) get to the ground safely.

      That chromate conversion does sound awesome, but is that useful outside of cosmetic applications? (self-repairing bumpers and rims, anyone?)
      • Re:Currently (Score:4, Informative)

        by gyrogeerloose ( 849181 ) on Monday May 19, 2008 @04:17PM (#23466668) Journal

        That chromate conversion does sound awesome, but is that useful outside of cosmetic applications?

        I'm not an expert in this but I believe the chromates the OP is referring to are the type typically used as corrosion inhibitors. If you've ever been inside military airplane, you might have noticed the bright green paint used on the interior. That's zinc chromate. You can see how a anti-corrosion layer which could self-repair would be of great use in harsh environments or safety-critical applications.

        • Jeeze, that one reads like it was posted by an ESL dropout. Please pardon the typos and grammatical errors; my excuse is that I was posting in a hurry because I was at work.

          Yeah, I know--lousy excuse...

        • Hmm, i had thought the green paint was some kind of safety color code or something... but know, knowing what it was, your are right - that would be quite useful. Long term maintenance costs would likely drop...
  • In before Terminator jokes.

    Also, I wonder when this will become cost effective for cars. I suspect it's going to be a long time before (cost of self-healing frame) - (cost of normal frame) < (cost to repair normal frame). That being said, this is going to be a fantastic option for a lot of industrial applications.
    • Re: (Score:3, Funny)

      by Bovius ( 1243040 )

      I for one welcome our flying Terminator overlords.
      And then,

      In before Terminator jokes.
  • How much weight does this system add vis-a-vis the use of non-composite materials? If you use a system that weighs more than the corresponding non-composite system, you won't gain anything by using the composites in the first place...
    • Re: (Score:3, Insightful)

      Any gain in weight over the normal composite material is far made up for in the fact that more and more non-composite parts can be replaced with these self-healing composite parts.
      • Remember that this technique involves filling what would otherwise be hollow fibers with resin and hardener. Therefore, while the healing might be advantageous, this material MUST, by definition, weigh more than the same composite without the added liquids, and does not add to the normal strength of the material.

        I would want to see comparative tests, with materials of THE SAME MASS... which means the unfilled composites would be thicker or denser. THEN compare whether the "healing" really gains anything,
    • Re: (Score:2, Insightful)

      by SBacks ( 1286786 )
      "A key benefit would be that aircraft designs including more FRP composites would be significantly lighter than the primarily aluminium-based models currently in service."
    • by stormguard2099 ( 1177733 ) on Monday May 19, 2008 @01:33PM (#23464534)

      As well as the obvious safety benefits, this breakthrough could make it possible to design lighter aeroplanes in future. This would lead to fuel savings, cutting costs for airlines and passengers and reducing carbon emissions too.

      This is my friend article, I don't believe you've met before.
    • by mcrbids ( 148650 ) on Monday May 19, 2008 @01:43PM (#23464636) Journal
      Many concerns with this kind of system.

      Airplanes aren't like cars; cars are mass-produced, throwaway items that seldom see more than 10-15 years of use. Yes, there *are* 30 year old cars, but they represent a rather small fraction of the actual cars in day-to-day use.

      Airplanes, on the other hand, are in a different category. Airplanes are all-but hand made. They are very expensive, so it's usually cheaper to fix an existing plane than to buy a new one. I got my pilot's license in a 1971 Cessna 172 that was older than I am. This isn't a particularly old plane, C-172s go all the way back to 1955 or so, and there isn't a whole lot that changed in the plane characteristics from 1959 to 2006 - mostly just newer instrumentation and a few minor tweaks.

      Since we can be fairly certain that many (most?) of airplanes made today will be flying 40 years from now, how well does this "self healing" work then? Composites are much more sensitive to extreme temperatures - how well does it "heal" at below freezing? (typical of high altitudes, as well as high lattitudes)

      Aviation is very risk averse - KISS is the rule of survival! Most planes are leaned MANUALLY just to avoid the possibility that some little spring in the carburetor would die while flying over mountains to the detriment of the plane occupants.

      Yes, even though I'm a technocrat, I remain a bit skeptical.
      • by Kelbear ( 870538 ) on Monday May 19, 2008 @02:06PM (#23464934)
        I suspect that the purpose is similar to that of the self-inflating tires. They keep you running until you can fix it properly. Since not all cars are equipped with flat-proof tires, it's a good idea for drivers to be acquainted with how to pull over and change a flat. However, manually patching hull cracks in mid-flight is an unreasonable expectation of a pilot, so this technology has found a niche.
        • That's actually a very good analogy. This system is a temporary fix for expensive carbon composite airframes to address micro(paper cut or smaller) sized fractures which could lead to wing collapse.

          Carbon fiber is far more resilient than aluminum. but it when it does break it breaks catastrophically. Minor cracks can grow. This system patches the minor cracks to begin with thus allowing the system to be patched later properly.
  • by Hojima ( 1228978 ) on Monday May 19, 2008 @01:24PM (#23464440)
    I'm no engineer, but wouldn't the use of new self-healing polymers be inferior to a mechanical failsafe or backups. If damage is done to an aircraft, the component of the structure that was carefully designed for a specific use is compromised. When under intense air pressure, self healing doesn't seem to make the cut. Wounds don't heal when aggravated, and bones have been known to heal badly (which could translate to a greater problem). If there is a new "healing" system that is to be used, I think it's a long way down the road before we see them implemented in commercial/military aircraft.
    • Re: (Score:2, Insightful)

      I don't think that this is going to be a big step back. I think it is meant more for skins and interior panels. There is little substitute for good old Aluminum or Titanium in aircraft. This isn't meant to be a massive fix just fix dents or you know the normal wear and tear of being an aircraft. If the composite break or fracture can reseal itself it is less downtime, less cost and easier overall on the parties involved. I think this wouldn't be used for airframes. Having little gaps of liquid would make t
    • by Harmonious Botch ( 921977 ) * on Monday May 19, 2008 @01:35PM (#23464562) Homepage Journal

      ...and bones have been known to heal badly (which could translate to a greater problem)....
      "Ladies and Gentlemen, there will be a momentary delay while try to open the doors. Please do not be alarmed, this is just a slight, though predictable malfuction of our aircrft's self-repair system."
    • by spun ( 1352 )
      I believe the damage we are talking about is micro-fractures that would be filled in with self healing goo. I think that the issue is more materials fatigue than macro scale damage.
    • Re: (Score:3, Informative)

      by vertinox ( 846076 )
      I'm no engineer, but wouldn't the use of new self-healing polymers be inferior to a mechanical failsafe or backups... Wounds don't heal when aggravated, and bones have been known to heal badly (which could translate to a greater problem)...

      I don't think they intended this to be a long term solution to aircraft damage, but rather keep the airplane in the air until it can land safely and then the ground crew can make long term repairs.
    • by Solandri ( 704621 ) on Monday May 19, 2008 @03:03PM (#23465606)

      I'm no engineer, but wouldn't the use of new self-healing polymers be inferior to a mechanical failsafe or backups. If damage is done to an aircraft, the component of the structure that was carefully designed for a specific use is compromised. When under intense air pressure, self healing doesn't seem to make the cut.
      FRPs like fiberglass and carbon-fiber are composed of strengthening fibers embedded in a polymer matrix. The fibers provide the strength, the polymer holds the fibers together with each other (transfers load from one fiber to its neighbors). The initial modes of failure will be the polymer losing its "grip" on the fiber (like pulling a nail out of wood), followed by fracture of polymer that's lost its fiber reinforcement in this manner. The fiber is still there and intact, it's just lost its mechanism for accepting load from adjacent material. Initially there's enough polymer that stresses can be routed around a minor failure of this type (transferring load to adjacent fibers). But eventually you get to the point where you'll have multiple dislocations spanning between fibers, and the polymer is no longer able to transfer stresses to enough fibers to carry the entire load, eventually leading to catastrophic failure.

      This self-healing mechanism essentially injects new polymer into the crack thus reseating the fiber within the polymer, sealing the polymer dislocations, and restoring the polymer's ability to transfer load between fibers. The dye to indicate a failure is to catch an inspector's attention just in case the stresses exceeded the fiber's breaking strength (e.g. from a rock or birdstrike). The presence of the dye does not in itself indicate the part is now substantially weaker than a new part (aside from the self-repair mechanism being used up).

      Yes, the "healing" polymer is probably not as strong as the original polymer. But because of the nature of the failure mechanisms I've described above, any FRP already has plenty of leeway for polymer failure built into it. If it didn't, the material would be incredibly susceptible to fatigue failure after just a few load cycles.

    • I'm no engineer, but wouldn't the use of new self-healing polymers be inferior to a mechanical failsafe or backups.

      Mechanical failsafe? Backup? Okay Mr. No Engineer, perhaps you could explain how you provide a backup for a monocoque wing skin?

      Aircraft are often partly glued together and the technique can be used in cars as well []

      , I guess the Loremo actually uses some glued aluminum, or so I believe I've seen in some of their propaganda before.

      If you had an epoxy or something that would automatically squirt itself into fatigue cracks in aluminum, then air/UV harden, it would be a major blow for freedom. Now, write tha

      • by Hojima ( 1228978 )
        From RTFA I saw that it was meant for micro-fractures etc. When you talk about bullet holes, you either have air pressure going into the wing and pushing the liquid back, or air pressure going under the wing, creating a vacuum that depletes the healing liquid. Now as for monocoque wing skin, I assume that the parts are glued so that chemical hazards are not a problem, and physical hazards have been tested. Now it seems to me that you are worried about bullets. Let me assure you that the only way to repair
    • IIRC, a much more primitive type of "self-healing" technology was instrumental in the WWII Allied victory.

      Fuel tanks for aircraft used a sandwich of aluminum and a polymer that hardened on contact with air (similar to the gunk you can get at the Autoparts store to stop a leak in your gas tank).

      Fuel leaks from gunfire or flack stopped or slowed dramatically, reducing the risk of fire and the need to bail out prematurely because of fuel loss (remember, some of these missions were extremely long, especiall

    • by geekoid ( 135745 )
      This would be used in addition to the things you mentioned, not instead of.
  • world war 2 (Score:2, Informative)

    self sealing fuel tanks. []
  • by Starker_Kull ( 896770 ) on Monday May 19, 2008 @01:38PM (#23464590)
    My first worry upon reading the idea would be that some dim bulb would propose that we need to reduce the number of heavy tear-down inspections to look for fatigue damage, since they 'self-repair'. But the article proposes using not only a resin that flows out to repair broken fibers, but putting dye in the resin so that fatigue cracks (and the subsequent self-repair) are much more obvious to inspectors.... To quote the article:

    "This approach can deal with small-scale damage that's not obvious to the naked eye but which might lead to serious failures in structural integrity if it escapes attention," says Dr Ian Bond, who has led the project. "It's intended to complement rather than replace conventional inspection and maintenance routines, which can readily pick up larger-scale damage, caused by a bird strike, for example."
    Nice idea... I hope we see it deployed in production aircraft someday.
    • Re: (Score:3, Interesting)

      by rkanodia ( 211354 )
      Hopefully the dye will only be visible under UV light, or else I am going to freak the hell out when I see purple veins start to bubble up from the surface of the wing of the plane I am flying in.
      • I am going to freak the hell out when I see purple veins start to bubble up from the surface of the wing of the plane I am flying in.

        You have a problem flying in a toaster? If it's good enough for Star Buck, it's good enough for you.

    • Re: (Score:3, Interesting)

      by wsanders ( 114993 )
      Well, then the danger is the mechanic in a hurry or under pressure is going to see the spar covered with filled in cracks, and say "it must be working OK!"

      Still, probably better than the explosive decompressions one gets with aluminum.

      Back in the old days, a good agent for finding these problems was the tar from cigarette smoke. If a small hole or crack occurred, the sludge from accumulated smoke would seep out of the crack under pressure and produce a visible stain. The crack would often self seal, althoug
  • I think this is great. Imagine the day when every component of machinery is self-healing. Machines will have skin, bones, circulatory systems, and yes, brains. With each new technology, we're recreating/modifying nature and ourselves.
  • by veganboyjosh ( 896761 ) on Monday May 19, 2008 @01:51PM (#23464726)
    healing processes we see after we cut ourselves,

    Speak for yourself, emo kid.
  • "I don't think so, Dave"
  • ...Reading that as "self-hating system" and thinking it was a good idea, though probably "self-loathing" would do.
  • I envision lots of FAA inspectors looking at a lot of half healed parts by the crater, instead of parts not healed at all.
  • The article does not say that the technique is being used in any designs. It says:

    "The new self-repair technique developed by the current EPSRC-funded project could be available for commercial use within around four years."

    It's a nice sounding lab exercise, but it's not being used in any new designs, and won't be for a few years, if ever.

    • Re: (Score:2, Informative)

      by SBacks ( 1286786 )
      That's actually caused by the fact that its used in Aerospace applications. The testing/qualification process to get a part into operation takes 4-5 years minimum, and usually more like a decade. If they forecast this being in use in 4 years, then its got to be pretty much ready for full scale testing now.
  • In the 1980's was just lowly 2nd LT in the Air Force and one of my many duties was to tow targets for AAA crews. This time it was pulling targets for the Sargent York Anti-Aircraft system and during one runs the Sargent York AA system start hitting my F-5 rather the tow target. My F-5 was damaged but was barely airworthy and I got the F-5 on a backup runway near the test site. This was my closest time I ever needed to pull the ejection handle in my life and I was other combat operations after this. I wished
  • This isn't self healing any more than a scab represents a healed wound. When aircraft wings bleed nano-agents that reweave the carbon fibres, then I'll call the system self-healing. Until then, label it correctly. Self-patching, or even more correctly, damage-mitigating materials or design.

Life in the state of nature is solitary, poor, nasty, brutish, and short. - Thomas Hobbes, Leviathan