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Impact loading for a lowered object

  1. May 11, 2017 #1

    Trying to look at the impact loads on an object when it is lowered by a crane. Assuming a constant crane lowering speed and a known stiffness of the item onto which the object is lowered. ie a mass being lowered onto a beam at a constant speed. I've looked at the classic impact equation for the dropping of objects onto beams , but not sure how to adjust them for lowering of a suspended mass. Any help will be much appreciated.

  2. jcsd
  3. May 11, 2017 #2
    A lot depends upon the shape of the two surfaces where they will come in contact. What did you have in mind?
  4. May 11, 2017 #3

    jack action

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    A very crude approximation would be the conservation of energy:
    $$E_k = E_s$$
    $$\frac{1}{2}mv^2 = \frac{1}{2}kx^2$$
    $$x = v\sqrt{\frac{m}{k}}$$
    • ##m## is the mass of the object;
    • ##v## is the speed of the object;
    • ##k## is the vertical stiffness of the beam;
    • ##x## is the vertical displacement of the beam.
    The impact load is then ##F_i = kx = kv\sqrt{\frac{m}{k}}= v\sqrt{km}##.
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