Buckling Analysis - Cantilever Beam 1

[salukice]

Hello,

I have a very generic problem of a cantilever beam with a load at the end and am trying to calculate the critical load. I have calculated the critical load to be about 32,000 psi. When I run the analysis through Pro E Mechanica, the first buckling mode is supposed to occur at about 12,000 psi and the second at about 32,000 psi. Why would my hand calculations have found the second mode instead of the first mode?

Also, if anyone knows of a good place either on the internet or a good book to learn more about buckling, please let me know.(Preferably internet resources)

Thanks in advance for any help anyone can give me!

 

[SWComposites]

Please post a figure showing the beam, loading and boundary conditions.

Also post the ProE mode shapes.

What solution are you using for your hand calculation?

Why are you quoting buckling in terms of psi and not load (lbs)?

If this is a cantilever beam with a transverse load, it is likely to fail in bending, not buckling.

 

[rb1957]

i think Pro may be telling you about buckling about the weak axis of the beam, which could be irrelevant to your problem, and the strong axis which is relevant 'cause that's the solution you calculated.

 

[GregLocock]

Or you may have underconstrained the Pro E model, or overcosntrained your hand calc (eg assuming 0.75 of a sine wave as the deflected shape, when it should be 0.25 wave).

Cheers

Greg Locock

SIGlease see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[TERIO]

Buckling References:

Robert M. Jones, "Buckling of Bars, Plates, and Shells". Search for it on google books, I believe you can read the whole book there.

Timoshenko and Gere, "Theory of Elastic Stability". A paperback reprint came out recently for about $15.

 

[Twoballcane]

Are you comparing a horizontal beam that is fixed at one end and free on the other with a load on the free end causing deflection with a beam that is vertical with a compression load going down the axis of the beam (bucking)? These are two different situations.

Tobalcane
"If you avoid failure, you also avoid success."