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Linear metal expansion - For an Old timer

  1. Mar 24, 2012 #1

    DHA

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    Hi all

    I am a newbie here, so please go gentle

    It is along time since I have had to use Thermal Co-efficients of expansion for various metals.

    However, I am trying to tie in some figures I have been given to what I know to be reality.
    i am sure that I am doing something basically wrong, or the whole theory of such science will hve to be re-written

    Now I know that aluminium expands at a rate of 1 or 2 mm per metre ( depending on colour ) I am involved here with the flashings on buildings , so thicknesses from 0.9mm to 3mm thick )

    Given that knowledge ( unless the building industry is wrong ) I have been given a co-eff of 22.2 x (10 power -6) m/m K (Not sure how to get -6 as supertext )

    How do I relate that back to a dimension of 2mm or so that I am familiar with ( I am sure I can not count the right number of zeros ) but hey it's well over 40 years since I did this and a good 50 since I did it at school

    Much appreciated

    A confused Old Timer

    DHA



    PS Perhaps I should add ~ I am moving decimal point 6 places to left, then 3 to right (to bring to mm ) obviously wrong as it is no where near ??
     
    Last edited: Mar 24, 2012
  2. jcsd
  3. Mar 24, 2012 #2
    When you say 1-2mm expansion for 1 m bar, what is the temperature change producing this expansion?
     
  4. Mar 24, 2012 #3

    NascentOxygen

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    Staff: Mentor

    Hi DHA! http://img96.imageshack.us/img96/5725/red5e5etimes5e5e45e5e25.gif [Broken]

    That means for every degree Celcius it is heated, each metre of length (and thickness) expands by 0.0000222 metres (i.e., by 0.0222 mm).

    So a 100°C rise would see each metre of it stretch by 2.22mm.
     
    Last edited by a moderator: May 5, 2017
  5. Mar 24, 2012 #4

    DHA

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    OK Forgot about temp difference, How thick am I ?

    Thanks
     
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