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A (hopefully) easy question to answer about cantilever beams

  1. Mar 3, 2007 #1
    Hi guys,

    just wondering if you could help me out?

    For a standard rectangular cross-section cantilever beam with a concentrated end load how do i work out the top surface stress at a point along the beam? do i just use sigma=My/I where y=half the depth of the beam and M=end load * distance from end load to point of interest ...?

    This sounds right but i'm not certain..sorry, hope this is easy enough to answer.

    thanks a lot!

  2. jcsd
  3. Mar 3, 2007 #2


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    What do you mean exactly?

    If you want the flexionant stresses to the extreme fiber on compression (or tension) of the beam, M will be the corresponding moment at the distance (where you want the stresses) from the diagram (which in this case is a triangle), y will be half of the depth of the beam, and I the area moment of inertia of the beam in the axis of the acting moment.
    Last edited: Mar 3, 2007
  4. Mar 3, 2007 #3


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    Sure, your standard formula will apply, unless there is something you didn't tell us about which means it does not apply.

    For example if it is a short beam, or you want accurate stresses where a load or restraint is applied, or there are large deflections, or the material is anisotropic, or the loads are big enough to cause nonlinear material behavour, or ....
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