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A Can a simply supported beam be a cylinder?

  1. Dec 21, 2016 #1
    I have an application where I am trying to figure out the shock load being applied to a metal pin (load cell).

    It is a cylindrical load cell which is supported at either end, and compressed in the middle. There is a slight gap between the end supports and the section compressed in the middle, this provides shear force across two planes which is measured by strain gauges.

    In our situation we know the output from the strain gauges at 500Kg shear force, but the output at 0kg is becoming offset after use, and I need to try and figure out how much force is being applied to create this offset.

    I don't really know where to start, but in my reading so far it seems like if I could treat the pin as a simply supported beam I might be able to make a start. So back to my question, can a cylindrical pin be considered as a simply supported beam?

  2. jcsd
  3. Dec 21, 2016 #2


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    Science Advisor
    Gold Member

    If your load cell has never been significantly overloaded then I doubt whether you have damaged it .

    It is always possible though that your shock load has a short duration spike in it which is causing problems .

    Load cell set ups sometimes develop an off set without them being in any way damaged . Normally this offset is just trimmed out .

    Answer to your actual question is that a beam can certainly be cylindrical in shape .
    Last edited: Dec 21, 2016
  4. Dec 21, 2016 #3

    thanks for the reply - I know that the offset on the load cell is too large to be attributed to drift or output change once in situ. The load cell output is certainly damge of some description, what I am trying to determine is if it is overload, shock or torque that is causing it.

    i'll look more into the maths!

  5. Dec 21, 2016 #4


    Staff: Mentor


    Wouldn't it be better to remove it and directly inspect the part after the damage? With a little magnification you can probably see what the cause is.
  6. Dec 21, 2016 #5
    How would you see it by magnification?

  7. Dec 21, 2016 #6


    Staff: Mentor

    With a low power microscope or a hand held magnifying lens.
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