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Bending of a varrying cross section

  1. Sep 17, 2011 #1
    Recently, I had lab. In the lab we took different objects and measured their strain. One object had a varying cross section. The data for strain was recorded. Right now, i'm trying to make a stress strain graph, but the problem is my equation for stress. I don't know how i can take my moment of intertia about the z-axis. I looked all over the web. In addition, I tried contacting my TA but no success for the pass 3 days. If you can help, I would appretiate it.

    Edit: I have the equations for the slopes. The problem lies with my moment of inertia.

    Attached Files:

  2. jcsd
  3. Sep 17, 2011 #2


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    The problem as shown leaves one asking a few questions. I don't know which is the z-axis.

    According to the problem statement, the depth of the beam is constant; apparently only the width varies. Why don't you calculate the moment of inertia at several different locations and draw a curve of inertia versus distance from the fixed end?
  4. Sep 19, 2011 #3

    Are you certain that you need to solve for more than two dimensions?

    According to your problem statement, your height (i.e., your x-axis) is of constant dimensions.

    As your diagram is, according to your problem statement, viewed from above, it's your x-axis that's sticking out from the paper. The only varying dimension is the z-axis (which is the up-and-down axis on your diagram). The y-axis is, as usual, the left-right axis on your diagram.

    I hope this helps.
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