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Homework Help: Buckling of a short structure

  1. Jun 2, 2010 #1
    1. The problem statement, all variables and given/known data

    Finding the critical buckling load of a really short column with wide cross section (is it still considered a column?)

    E = 22 GPa
    Yield: 300 MPa
    Load: 28N
    thickness: 0.226 mm
    I = 670706.51 mm^4 (is this right?)
    Load Applied Area (as indicated by white arrows): 190400 mm²

    Presentation1-2.jpg

    I understand from http://www.engineersedge.com/column_buckling/column_ideal.htm that I should be applying Johnson's Formula.
    2. Relevant equations

    Euler Buckling :

    [URL]http://172.31.254.243/www.engineersedge.com/column_buckling/image/column1.gif[/URL]

    Johnson's Formula

    [URL]http://172.31.254.244/www.engineersedge.com/column_buckling/image/johnson.gif[/URL]



    3. The attempt at a solution

    Using Johnson's formula, I've found out the Critical Buckling Load (Pcr) is 57119986 N

    I know this is a really short structure with a wide cross sectional area so naturally the Pcr will be bigger but could someone please verify my method?
     
    Last edited by a moderator: Apr 25, 2017
  2. jcsd
  3. Jun 2, 2010 #2

    minger

    User Avatar
    Science Advisor

    I don't think that will work. Typical buckling problems assume a deflected shape, which you won't get.

    The issue is not that it is short, but that it is thin-walled. Roark gives an idea for thin-cylindrical tubes, but not thin-rectangular tubes. I will quote his paragraph, 12.3 Columns and other Compressions Members
    My best guess would be to perhaps run a really good buckling model in ANSYS/Nastran and give it a good safety factor.
     
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