# Shell vs. brick elements in buckling analysis

Dear All:

I have a structural problem which deals with "Buckling" analysis of a boom with a rectangular cross-sectional area

and 0.25 in. thickness.

Can I use brick element (8 nodes) instead of shell element to simulate buckling of this type of structure?

David.

### brick OR shell might be ok

It is possible that you could do such an analysis with shell elements OR brick elements.  If one dimension of the boom is quite thin, relative to the other dimensions, then it might make sense to use an appropriate shell element.

However, the question is not what element should you use, but rather whether or not your finite element analysis program can do geometrically nonlinear problems?  Since buckling is a large displacement, geometrically nonlinear problem your FEA program will have to use finite strains and consider geometric effects.  Alternatively, the FEA program may be able to do the analysis with small strains but by using a corotational formulation.

You need to look at the capabilities of your FEA software and see if it can handle geometrically nonlinear problems.

Also, you may need to ask if you think the buckling will be entirely elastic, or if it will be inelastic buckling?

If inelastic buckling then it will be geometric and material nonlinear and you will have to specify an appropriate material model to mimic the material used to construct the boom.

regards,

Louie

### we can't use blindly brick

we can't use blindly brick or shell element since there may be chance of getting local or global buckling as a critical load. again it depends upon the length and width of the cross section you are considering. in general brick element predict only global buckling and where as shell elemnt having the capability of predicting both global , local and even interaction buckling.

so please take care of it.

regards,

K.Ramkumar