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My gate !

  1. Feb 8, 2013 #1
    hey guys >>>

    in this morning i woke up ... and Without prior warning

    my gate Turned to this (look at pic )

    1- What is the reason I want to know?

    can any body tell me ??????


    http://hh7.an3m1.com/Sep/an3m1.com_13603318841.png [Broken]
     
    Last edited by a moderator: May 6, 2017
  2. jcsd
  3. Feb 8, 2013 #2

    Borek

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    Staff: Mentor

    Re: my gate !!!!!!!

    Three first things that come to mind - hit, temperature gradient, twisting frame.

    And you are not alone, such things happen.
     
  4. Feb 8, 2013 #3

    jedishrfu

    Staff: Mentor

    Re: my gate !!!!!!!

    I assume you mean the glass just shattered for no apparent reason. It looks like its safetyglass which is two panes of glass with a plastic inner liner

    Its hard to say why, but glass under stress will sometimes need one little push to do that like slamming the door, a sonic boom, temperature change, air pressure change...

    I once witnessed this in a game arcade where my friend removed a piece of glass from a pinball machine and placed it to the side of the machine. When he gently picked it up to reinstalled it, it just shattered. It really shook him up. I think what had happened was he flexed it somehow and that was enough to initiate the fracture that shattered it. It was also probably under stress for a long time with folks banging on it while it was on the pinball machine.
     
    Last edited: Feb 8, 2013
  5. Feb 8, 2013 #4

    phinds

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    Gold Member
    2016 Award

    Re: my gate !!!!!!!

    That doesn't seem to make sense. The POINT of safety glass is that it does NOT shatter and fall apart like that ... it will crack like crazy but hold together.
     
  6. Feb 8, 2013 #5

    jedishrfu

    Staff: Mentor

    Re: my gate !!!!!!!

    Isn't that what you see, a bunch of cracks but it hasn't fallen out? I'm not sure two pane glass would do that and stay in place.
     
  7. Feb 8, 2013 #6

    jbriggs444

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    Science Advisor

    Re: my gate !!!!!!!

    This looks like tempered/toughened glass, rather than laminated safety glass. It is a characteristic of tempered glass that any tiny crack will instantly propagate and craze the entire pane into a network of small pieces. Lamination, if present, would not cause this effect.

    According to wiki, the term "safety glass" is generic and covers implementations using either tempered glass or laminated glass.

    In a vehicle you will typically find laminated safety glass in the windshield and unlaminated tempered glass in the side windows.
     
  8. Feb 8, 2013 #7
    Re: my gate !!!!!!!

    It does look like the unlaminated tempered glass one finds in automobile side windows. If that's the case, rescue personnel use a spring-loaded center punch to break out the window. Using a rock or hammer usually spreads the impact too much to make the glass break, but any short-sharp blow could cause it to look like your photo...
     
  9. Feb 8, 2013 #8

    Nugatory

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    Staff: Mentor

    Re: my gate !!!!!!!

    As others have said, that's the typical breakage pattern for tempered glass. If you had been watching, it probably didn't happen all at once. Instead a single crack forms, and then spreads while new cracks appear over a period of several minutes.

    When it's done destroying itself, you'll have chunks more like gravel than broken glass, with some sharp edges but nothing that is likely to do serious injury. By comparison, a piece of ordinary plate glass in a doorway would break into large sheets projecting into the opening and quite capable of slicing to the bone and through major blood vessels.
     
  10. Feb 9, 2013 #9
    thanks guys >>> for all Information
     
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