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Steel Plate Thickness issue?

  1. Aug 13, 2012 #1
    I'm using the basic deflection equation to determine how thick a plate of steel would have to be to support a load of approximately 1300 N in a 3 point bend, with surface dimensions of of 420 x 630 mm.

    I = bh3/12; δ = FL3/(C1EI); Esteel = 200 GPa = 200 N/mm; δ = 50 mm (arbitrary);

    h3 = 1300*(4203)*12/(48*50*630*200)

    I'm getting a result of 15 mm... to me that seems a bit thick, especially when the weight would be close to 33 kg. Am I missing anything?

  2. jcsd
  3. Aug 13, 2012 #2


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    Grant_: Nice work. You currently used the wrong units for E. Try again.
  4. Aug 14, 2012 #3
    Your value of E should be in MPa in the equation (i.e. N and mm = MPa). So E = 200000e6. So answer is 3.8 mm?
  5. Aug 25, 2012 #4
    I usually cross check structural calculations like this with BeamCALC or some other tool.
    The bookkeeping along with units variations can cause errors to creep in.
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