Euler buckling simulation


#1

If I set up a simple vertical hollow tube (20mm OD, 16mm ID, 400mm long, aluminium) with a fixed constraint on the lower end face and a compressive load on the other which exceeds the critical Euler load (>>80kN) the simulation doesn’t obviously demonstrate Euler buckling. The only way to tell there is a problem is that, once the load exceeds the Euler critical load, the displacement becomes static. Is there a better way to visualise this?


#2

Good evening @irving,

this is already on the roadmap of SimScale as mentioned by @ahmedhussain18 in this post.

@afischer or @dheiny might give you an insight into that upcoming feature.

Cheers,

Jousef


#3

Thanks for that information & link. I note you consider this a 2d problem but that’s just an artifact of the way that @alabrazi presented his problem. Mine is ultimately a 3D problem as the columns are legs to a structure.

There is a more general point here - the representation of failure modes in SimScale. If I set up a simple bending of beam example and I increase the load the only indication I have of failure of the beam is when the displacement becomes non-linear. Or am I missing something?


#4

Hi @irving,

that is right. I was just referring to buckling in general (2D as well as 3D).

Concerning your question about the representation of failure, consider this post of @rszoeke:

Show overload of a structure

Does that somehow cover the wishes you have for the representation?

Best,

Jousef


#5

@Jousef

Thanks, that’s a very useful approach.

It would be nice, in the future maybe, to see failure graphically represented in the WarpByVector filter (or, better, a dedicated ‘Failure’ filter) based on the material properties and a ‘safety factor’ value.

rgds,
Irving


#6

Hi @irving,

I already transferred your feature request. @afischer will keep you up to date.

Enjoy your stay here and have a nice weekend!

Jousef


#7

Hello @Irving,

thank you for your feature request! As @jousefm mentioned I will keep you up to date. We will also collect more feedback from the rest of our users in the near future! I keep you updated!

Best Alex


#8

I’m also interested in same, can you also notify me if this feature is on track?


#9

Hi @gkotelnytskyy!

I will definitely keep you up-to-date, no worries! :slight_smile:

All the best!

Jousef


#10

Hi @gkotelnytskyy,
please don’t forget to vote for this feature here: Buckling analysis feature addition request

Best,
Richard


#11

Is there some workaround before the feature is added.
I.e. applying small lateral force to the column – would it work to the same effect?


#12

Hi @gkotelnytskyy,
as long as you know in which range the critical load will be. this might work.
I made a small example, with a fixed end + pinned collumn under compressive load: https://www.simscale.com/projects/rszoeke/buckling_test/

From hand calculations the critical load should be about 30.31KN.
The nonlinear analysis shows a buckling behavior between load step 0.7 and 0.75, at an total applied of 40KN, whis is betwen 28KN and 30KN:

Best,
Richard


#13

Thanks a lot, @rszoeke, this is the most helpful.

Why did you use non-linear simulation in your project? Isn’t buckling linear at first?


#14

Hi @gkotelnytskyy,
this is exactly what this is about. As we don’t have “Euler buckling” available we need to go with a nonlinear analysis to be able to represent the change in geometric stiffness due to applied loadings and small geometric perturbations.
If we would have used a linear analysis, the above graph would stay linear for any given load.
Best,
Richard


#15

A post was merged into an existing topic: Matrix not factorable