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  1. #1
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    Thumbs down Failure Report: Tyvek

    I know everyone loves to talk about how great their hammock is and post pics of their feet, but if you want to know anything about the strength of a design you need failure data. Hence this post of negative results.

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    I made this hammock last spring. It's Dupont Tyvek housewrap, 9 feet long (didn't measure hammock width), with double sheet bends at either end. The blue cord is a structural ridgeline (Amsteel) and it was hung with a reasonable sag angle (see photos). It was in backyard use (i.e rarely longer than a nap per day) for a few months last winter and this spring I'd used it about four times prior to failure. It was stored folded in a bag.

    Today I hung it and got in. There was no obvious damage when I hung it. After about 15 seconds of lying down (i.e. all initial transient loading had died out), it failed with a bang. No identifiable sound of ripping. 90% of the width tore within milliseconds. When I pulled on the tear after failure, it continued to tear with *very* little force (less than tearing paper). I weigh about 175 lb.
    Last edited by tkw954; 05-09-2012 at 21:10. Reason: Sheet bend, not lark's head

  2. #2
    Senior Member nacra533's Avatar
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    I haven't heard of folks trying a Tyvek hammock but I've been gone a while.

    Sacks, tarps, Jerry chairs, sit pads, cooking areas are the uses I am familiar with.

    Glad you're OK. I had a hammock I made for a friend from 1.7/1.9 ripstop fail in the fabric on night one of a 3 night trip. Fortunately, no injuries and he had a pad to go to ground on.
    Last edited by nacra533; 05-09-2012 at 19:23. Reason: Spelking. spelling#%€$& iPad autocorrect!

  3. #3
    Senior Member mangus7175's Avatar
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    First time I've seen anyone make a hammock out of tyvek before. Seen ground sheets, tarps, even bivy's made from this material but not a hammock.

    Based on articles I've read about Tyvek, it has a fabric tensile strength of around 30 to 40 pounds, which clearly your weight exceeded...

  4. #4
    in it for the naps oldgringo's Avatar
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    Did you leave the hammock up last summer for any length of time? I've read that Tyvek has little resistance to UV degradation.
    Dave

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  5. #5
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    I did leave it up last summer, but it was well shaded.

  6. #6
    Senior Member Beast 71's Avatar
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    Quote Originally Posted by mangus7175 View Post
    First time I've seen anyone make a hammock out of tyvek before. Seen ground sheets, tarps, even bivy's made from this material but not a hammock.

    Based on articles I've read about Tyvek, it has a fabric tensile strength of around 30 to 40 pounds, which clearly your weight exceeded...
    30 to 40 pounds No Problem! I'd just have to make a 10 layer hammock .
    "In your face space coyote"-HJS

  7. #7
    Senior Member dukedante's Avatar
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    That's an interesting place to rip, I would have thought it would fail at the lark's head. I've had a tyvek tarp fail, but it was at a place where the fabric had repeatedly been folded and was pretty high stress next to a tie out. It does fail magnificently though, doesn't it?

  8. #8
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    Quote Originally Posted by dukedante View Post
    That's an interesting place to rip, I would have thought it would fail at the lark's head. I've had a tyvek tarp fail, but it was at a place where the fabric had repeatedly been folded and was pretty high stress next to a tie out. It does fail magnificently though, doesn't it?
    I know, I would have expected that, too. I did a bunch of tarp/sail connection tensile tests and the failure was always about 6" from the connection. When I disassembled the knot on the hammock (actually a sheet bend), there was considerable deformation at the bend.

    This failure may have been a weakening due to folding for storage over winter.

  9. #9
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    Quote Originally Posted by Beast 71 View Post
    30 to 40 pounds No Problem! I'd just have to make a 10 layer hammock .
    Yep! LOL A problem of using products for things other than what they are designed and made to do. Can create a dangerous situation. So, use caution. I'm glad there was no injury, except to pride.

    Rain Man

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    "You can stand tall without standing on someone. You can be a victor without having victims." --Harriet Woods
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  10. #10
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    The Tyvek Homewrap is one of the lightest basis weight Tyvek styles DuPont produces. A while back there was a potential application for Tyvek to be used in place of a stretcher (for emergency situations to carry bodies) but none of the traditional Tyvek styles could support average body weight without failure. I'm glad you weren't hurt either!

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