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Homework Help: How do I calculate the energy density of a main-spring?

  1. Jan 27, 2013 #1
    1. The problem statement, all variables and given/known data

    How do I calculate the energy density of either a main-spring (like in a clock) or a motor-spring?
    Can someone show me values put into the correct formula for something like e.g. steel?

    I did find some material properties like this: http://www.engineeringtoolbox.com/yo...lus-d_417.html [Broken]

    The motor-spring I am interested in is a type like this: http://www.sdp-si.com/Gateway/D220-T183.htm

    Secondly, I would like to experiment with various materials (composites especially). If I make a plank of this material, how can I measure its properties to be able to put it into the correct formula for energy density of such a spring (if made into a spring)? I would have to take into account the breaking-point of the material of course (i.e. I bend the plank and at some point it either snaps or buckles).

    I did study mech. engineering for a coupple of years but it is 20 years ago and I am rusty ;-)
    I have googled and read a lot but am still stuck. Most stuff only relates to compression-springs but I need to work out spring constant of basically a beam (?) and not sure of to work out the breaking point (of the clockspring) when I know that a certain material will snap when it is deflected a certain amount.

    2. Relevant equations

    3. The attempt at a solution

    Thanks and Regards,
    Last edited by a moderator: May 6, 2017
  2. jcsd
  3. Jan 31, 2013 #2

    nobody knows the answer to this?
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