buckling analysis

[lukasz2]

HI

I’m trying simulate buckling. I started from beam model using BEAM3 element. I did eigenvalue and non-linear analysis (the results are good, I sure because obtained results are similar and probable in both analysis, besides I found tutorial in internet to do this). Then I tried did this analyses with exactly the same dimensions and properties of beam model but using SOLID187 element and I obtained different results of eigenvalue and non-linear analysis and also different than obtained using BEAM3 element.
Then I checked both models (BEAM3 and SOLID187) for deflection. Linear calculations were the same and non-linear analysis not. The deflestions of BEAM3 model are much bigger. It seems that I miss something in options??? How to simulate buckling of 3D elements???

Thanks

 

[cbrn]

Hi,
not intended to offend, but I'd suggest to carefully re-start from the basics and properly understand the theoretical differences between a 1D and a 3D formulation. Moreover, the simplifications / assumptions made for both the formulations have to be known.
Only after that you can venture into more complicated problems.
In what you are depicting I see no surprising things, but the reasons why are a bit too long to explain here (and it's most probably not the scope of a forum like this).

Regards