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ptc-3801071-Visitor
1-Visitor
July 14, 2004
Question

Buckling Load Factor

  • July 14, 2004
  • 1 reply
  • 1756 views
ProM Users:

I just used the ProM Buckling analysis module and have some questions.

To my understanding, a typical buckling study first involves a typical
static analysis. From this, a buckling analysis can be performed using and
based on the original static analysis. This all seemed to go well.

Does anyone have answers to the following questions on this topic:?

1. The B.L.F. (buckling load factor) is the only relevant data derived from
this study and is indicative of the magnification factor of the P(critical)
required to push the model to the critical deformation producing buckling?

2. The von mises stresses and deformation data produced from the buckling
study is not accurate.

3. The higher the B.L.F factor the buckling study produces, the less prone
to buckling your model will be. In other words, a higher B.L.F. is better
if your intent is to avoid buckling?

Any light anyone can shed on this topic would be greatly appreciated.

Greg Saiter
ABB Inc.
Columbus, Oh

    1 reply

    D
    david.reid1-Visitor
    1-Visitor
    July 15, 2004
    Greg

    Sound to me like you've got it right.

    Remember that this buckling capability only predicts the onset of buckling.
    Beyond that things get all very complicated and non-linear.

    Yes - a BLF of 1 or less indicates that your assigned load will cause
    buckling.

    No - it gives you more information than just that - it tells you what the
    buckling mode shape will look like. But yes be careful about taking stress
    and displacement data from these results - they involve linear
    extrapolation.

    If you get a negative BLF then this indicates that a buckling mode would be
    initiated if the load were reversed.

    If you have a thin structure under compression then the load required to
    cause regular failure will often be much higher than that required to
    inititate buckling. My recommendation is that you add features to your
    model to prevent buckling, until the BLF gives you a decent safety margin.
    I use the buckling mode shape to guide me to the best place to position
    stiffening ribs.

    I've seen many designs that have many regularly spaced ribs (supposedly to
    prevent buckling) but these have clearly been added purely based on human
    intuition. I'd rather use a more scientific approach to add them where they
    were most efficient.


    ---
    David Reid
    davidr@optima-design.co.uk
    Optima Design Services Ltd
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