Self-Healing System Applied to Aviation

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."

Comments

Planes were always self healing

[clonan]

So long as they came with their handy dandy bipedal humanoid repair agents...

Potential

[Oxy the moron]

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. :)

Have you seen this boy?

[ivanmarsh]

I for one welcome our flying Terminator overlords.

So...

[ZonkerWilliam]

The plane will heal itself after a crash. Great for the plane, not so much for the passengers.

Re:So...

[SBacks]

Unfortunately, this wouldn't have much of an impact on macro-scale damage. Its much more useful for those tiny microscopic cracks that can grow and lead to a failure. Much like when you slice your finger as opposed to cutting the entire hand off.

Currently

[bostonsoxfan]

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

[X0563511]

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

[gyrogeerloose]

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.

Re:Cost effectiveness?

[Bovius]

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

In before Terminator jokes. Ouch.

Re:One concern with this system

[stormguard2099]

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.

Re:A possible step back

[Harmonious Botch]

...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."

Quite clever, actually.

[Starker_Kull]

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:One concern with this system

[mcrbids]

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.

Re:Welcome!

[AKAImBatman]

I for one welcome our self-healing robot overlords

You know the great thing about bleeding robots? Put enough holes in them and they die just as easily as humans.

We (the human resistance) will remember your allegiances when we send in the full S.W.A.T. team with heavy weaponry and body armor.

similar to the bruising and bleeding...

[veganboyjosh]

healing processes we see after we cut ourselves,

Speak for yourself, emo kid.

Re:One concern with this system

[Archangel Michael]

This is my friend Slashdot. I don't think you've met before; we don't read articles and we make wild speculations based upon collective ignorance.

Re:One concern with this system

[Kelbear]

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.

Re:If it bleeds ...

[The Great Pretender]

What if it ain't got time to bleed?

Not for fibre-reinforced polymers

[Solandri]

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.