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Tube with variable diameter

  1. Jun 23, 2012 #1

    I am interested to know if a tube can be created that with some kind of mechanism, its diameter will increase on demand

    the range of the diameter should start at the smallest possible (0.01 mm or less if possible, even if the walls of the tube virtually concur) and increase up to 1mm or something

    the tube must have walls so that it will not bend easily (with less than 500grams force or so)

    any hints?

  2. jcsd
  3. Jun 23, 2012 #2


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    Gold Member

    What are the physical requirements of the tube? ie: Does it have to be waterproof, airtight, just cohesive enough for a ball to run along...?
    If the latter, a braided structure like what we Canucks call "Chinese finger puzzles" might work. Aside from that, I'm at a loss for now.
  4. Jun 23, 2012 #3
    It has to be absolutely liquid-proof
  5. Jun 24, 2012 #4


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    Staff: Mentor

    A tube made of a synthetic rubber will expand its bore on demand (the demand being pressure). House it inside a PVC pipe to contain its expansion. May not be able to quite meet your demanding specs, though. :wink:
  6. Jun 24, 2012 #5
    it shouldnt be able to bend, it should only be able to increase its diameter in a specific amount

    I imagine some force/energy would be needed to do the diameter increase

    that force/energy could be mechanical, like the above mentioned chinese puzzle, or in another direction, ie. something like a few rails running inside through the tube in parallel, and by moving them with a direction opposite to the centre of the tube, to increase tube's diameter, given that tube's walls are able to expand (tube can still be non bendable, because of the rails inside it)

    or there maybe other mechanical techniques for this?

    or maybe some kind of magnetic, electric, thermal etc energy could achieve that better?

    or there could be a specific material with such properties?
  7. Jun 25, 2012 #6


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    Does the expansion have to be linearly consistent, or are bulges allowed? I'm thinking along the line of NiTiNOL, specifically Biometal. That .01mm scale pretty much pooches anything that I can come up with, though.
  8. Jun 25, 2012 #7
    it has to be linearly consistent
    the 0.01mm scale is a must! :/
  9. Jun 25, 2012 #8


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    You have definitely piqued my interest, and I'll continue to monitor this thread. Unfortunately, I have absolutely nothing to offer. I hope that someone else can help you.
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