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Is this a tensile failure?

  1. Mar 8, 2014 #1
    I have been photographing wires hanging from utility poles that have tangled with and caused automobile accidents. One of these is a puzzle the detail shows a wire from a 7 strand wire rope made out of aluminum. It was too dangerous at the time to anything but drag the wire out of the road and the wire has been removed by the utility. http://www.flickr.com/photos/78934859@N04/12562669533/in/photolist-k97XYz-cabvfq-euZ4FC-hEtawu
     
  2. jcsd
  3. Mar 9, 2014 #2
    Can't you just upload the pic here ??? to view the pic one needs to sign up for flickr...
     
    Last edited by a moderator: Mar 28, 2014
  4. Mar 10, 2014 #3

    Baluncore

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    The wire appears to have been sheared diagonally.
    If it had failed under tension I would expect a ragged end or a thinning.

    It is possible that it was worn over time against an abrasive surface.
    Maybe swinging or vibrating in the wind.
     
  5. Mar 11, 2014 #4
    Here is the photo you can view it on flickr by searching "national electrical code" in quotes.
     

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  6. Mar 28, 2014 #5
    Definitely not tensile failure. I concur with Baluncore. You would see a thinning of the material at the point of break. Possibly broken when it was driven over and dragged along the roadway.
     
  7. Mar 28, 2014 #6
    It's really tough to say...
    (1) these cables are wrapped in a 7 cable bundle, most often twisted to maintain shape.
    (2) Power cables are in tension but they are catenaries, this, coupled with (1) could cause some very odd shearing action, especially coupled with other loads (wind, entanglement, etc)

    There's not much thinning in shear-tensile failures in wire rope. That's a really long "shear plane" (if that's what it is) though...

    These factors make it difficult to tell what had happened. Do you know the events which led up to this failure?
     
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