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Material with best tensile strength to weight ratio?

  1. Mar 22, 2005 #1
    Could anybody tell me what material will give the best tensile strength to weight ratio? I figure it's between steel cable and the nylon type stuff used in some dog leashes, but I'm not sure which.
     
  2. jcsd
  3. Mar 22, 2005 #2

    FredGarvin

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  4. Mar 22, 2005 #3
    http://en.wikipedia.org/wiki/Carbon_nanotube

    --
    Ray Baughman's group from the NanoTech Institute at University of Texas at Dallas produced the current toughest material known in mid-2003 by spinning fibers of single wall carbon nanotubes with polyvinyl alcohol. Beating the previous contender, spider silk, by a factor of four, the fibers require 600J/g to break. In comparison, the bullet-resistant fiber Kevlar is 27-33J/g.
    --
     
  5. Mar 23, 2005 #4
    Yes, but that's toughness/weight rather than strength/weight.

    The highest strength/weight ratio is usually found in whiskers in which there's no room for defects (so it might still be a nanotube) but it sounds like BasketDan has a larger-scale application in mind.
     
  6. Mar 26, 2005 #5
    carbon nanotube?
     
  7. Mar 27, 2005 #6

    PerennialII

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  8. Mar 27, 2005 #7

    NSX

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    I think Titanium has high strength:weight, since I remember reading an article about the NSX and it's Ti connecting rods.
     
  9. Mar 28, 2005 #8

    Astronuc

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    Some information to consider -

    Fibers
    http://www.machinedesign.com/BDE/materials/bdemat3/bdemat3_6.html

    Kevlar (Aramid)

    PBO (Zylon) - PBO consists of rigid rod chain molecules of poly (p-phenylene-2, 6-benzobisoxazole)

    Highest strength-to-weight ratio of any fiber
    Highest resistance to heat of among high modulus fibers (decomposes at 1200° F)
    Negligible creep
    Poor abrasion resistance
    Should be protected against degradation from light sources

    HexWeb® Honeycombs
    http://www.hexcelcomposites.com/Markets/Products/Honeycomb/Selector_HC.htm

    Titanium and Ti alloys
    http://www.key-to-metals.com/Article20.htm

    World's First Carbon Nanofiber Bridge Debuts
    http://www.netcomposites.com/news.asp?1699
     
  10. Mar 28, 2005 #9

    Gokul43201

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    In general, you want to go the composites way for strength to weight. Among metals, Ti and Ti alloys are pretty high. Among composites, (especially in the low strength regime) most FRPs have a very high s/w.

    Is this a question about a specific bit of trivia, or a general design related question ?
     
  11. Mar 28, 2005 #10

    PerennialII

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  12. Mar 28, 2005 #11

    Chronos

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    Aromatic polyamide fibers [e.g., Kevlar] have the highest tensile strength to weight ratio of any commercially available material.
     
  13. May 30, 2006 #12
    M5 Fiber

    I know I'm a little late on this reply, but I just read your question today. I am at a loss as to why no one has mentioned the M5 Fiber. So, I did a little googling and found some fascinating info at:

    http://www.m5fiber.com/magellan/m5_fiber.htm

    Currently, this IS the strongest, most versatile synthetic fiber that I am aware of. If anyone knows of another, please let me know, as I am always looking for new materials to experiment with.


    "So long, and thanks for all the fish!"

    ---- Bill Myers ----
     
  14. Jun 11, 2006 #13
    Kevlar and basalt fiber are two contenders on the practical scale; carbon nanotubes are the strongest on the laboratory/R&D world.

    But while there are many fibers that exist with high tensile strength, I still think man has not found any composite, polymer, ceramic, or metal that can come close to the versatility of steel.

    I find this interesting. Are there any specs on the mechanical properties of this polymer?
     
    Last edited: Jun 11, 2006
  15. Jun 11, 2006 #14

    Astronuc

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    The Magellan site has a page with the mechanical properties.
    http://www.m5fiber.com/magellan/m5_technical_info.htm

    It maybe sufficiently new that it is not yet in other databases.

    Interestingly M5 (pyridobisimidazole-2,6-diyl (2,5-dihydroxy-p-phenylene) is structurally similar to Zylon (p-phenylene-2, 6-benzobisoxazole). In M5, the oxygen in the benzobisoxazole ring is replaced by NH, hence the pyridobisimidazole, and the phenylene ring has OH attached at 2,5, hence 2,5-dihydroxy-p-phenylene.

    The patent 5,674,969 in the first in a series of four which discuss this and related polymers.
    5,674,969
    The three other patents are: 5,939,553, 5,945,537, and 6,040,478.
    Ref: Magellan Systems International.

    It would appear that Magellan's M5 will replace Kevlar and Zylon in certain (perhaps most) applications - although cost will play a role.
     
    Last edited: Jun 11, 2006
  16. Jun 11, 2006 #15

    russ_watters

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    Steel is actually pretty mediocre in that department. My guess is that Nylon's is several times that of steel (I tried to google it, but all I got was this thread! :bugeye: ) . There are lots of relatively mundane elements and alloys - even basic aluminum - that have much, much better strength to weight ratios than steel. And then there's the more exotic, like some of the things others mentioned. But as asked - what is the purpose of the question? Application makes a big difference.
     
    Last edited: Jun 11, 2006
  17. Jun 11, 2006 #16

    Astronuc

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    Russ brought up a very important (crucial) point - Application - or particularly - Environment.

    Environment certainly include temperature, but could also involve chemical (corrosion or chemical reaction) and radiation.

    High temperatures, might require refractory alloys, because organics would thermally decompose. Carbides of refractory metals would be required for even higher temperatures.

    High radiation environments can destroy organic fibers.
     
  18. Jun 6, 2008 #17
    Equation needed, please

    Would one of you be so kind as to tell me the formula (simplest possible, please) for determining the lowest number of fibers of a particular tensile strength, bundled together into the lowest number of cables, that would be required to lift an object of, let's say, 1200 lbs.? (Physics isn't my forte, so please keep it simple for me. Thanks!)

    Also, would the equation change over time? What I mean is, would the fibers of the cables weaken enough to change the equation between lifting the object 10 feet versus 50 feet in the air? Let's assume that no other outside forces (wind, for instance) are involved. Thanks.
     
  19. Jun 6, 2008 #18
    Oops. I should have said "minimum of four cables" rather than "lowest number of cables." Sorry.
     
  20. Jun 18, 2008 #19
    Don't ignore your basic wood. That's right. Wood comes in many forms. It's really hard to beat, light, strong, underrated. It's a secret weapon. Tell me what you thindk is better than wood. I could use a laugh. I should ask what your application is. Oh. that's it. Oh, that changes everything. The answer would be...........WOOD!
     
  21. Jun 19, 2008 #20
    Thanks for your help.

    I appreciate your reply to my question. I apologize for not providing the application initially.
    I am a theater owner, and I need to hoist a heavy (800 lbs.) set piece with the least visible cables possible. I was hoping some sort of wire or fiberoptics cable might work . . . I could attach a lot of cables . . . I was wondering if there is a basic formula to calculate how many fibers of a particular strength it would take to do the job. Thanks!
     
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