Euler and Global/Local Buckling

[drennon236]

I was trying to find out what Global Buckling is, and someone defined it as: "Global buckling is classical Euler buckling. This has to do with the “global” cross-section properties (EI) and the beam/column unbraced length “L”."

I understand Euler Buckling load can be found with the help of an equation, but how does it relate to global buckling? Does global buckling means it just buckles "everywhere", while local buckling is limited to small areas of the structure?

 

[EdStainless]

In my experience;
Global buckling is when you have a perfectly symmetrical part with perfectly symmetrical (or some very well defined eccentricity) loading and you exceed the limits and you get bucking failure.
In local buckling you are usually talking about some localized anomaly, such as distortion, dimensional or property variation, or point loading that causes buckling.In both cases the buckling is a complete failure.
In the real real world local buckling is what you nearly always see, ideal materials and loading simply don't exist.

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P.E. Metallurgy, consulting work welcomed

 

[ESPcomposites]

On the structural analysis side, we would consider global buckling of a column to be the "overall buckling" of the cross section. The entire column curves in this scenario (but the deformed cross section has the same shape throughout the column - at least at the macroscopic level). If we consider an I-beam, local buckling could be the buckling of just the flange or the web, but can occur at a load that is less than global buckling load (and in this case, the deformed cross section would not be the same throughout the length - there would be local "waves" in the deformation of the flange/web).

P.S. We might also consider "overall buckling" of a column to be the case where the column can no longer carry additional load (as opposed to local buckling since the column may be able to carry additional load). However, this is not necessarily the Euler load. The column can be a short/intermediate column (Johnson range of the Johnson-Euler solution) and this would also be considered "overall buckling".

Brian

http://www.espcomposites.com

 

[Eagleee]

usually people refer to those terms as:

1. local buckling - instability of a component of a structural member (e.g. the flange of a beam as ESPcomposites notes)
2. global buckling - instability of a structural member
3. global buckling - instability of a structure

From here, it depends on what level of detail you want to go into. Usually it is clear from the context if by 'global buckling' no. 2 or no. 3 from above are referred to. Attached a very quick paint sketch.