Dynamic buckling beam - imperfection

paula94

Hello, 

 

I work on a vehicle suspension optimization. For that purpose I need to perform a dynamic buckling analysis of a tube (meshed by 1D beam elements). I have already performed static analysis, static buckling and modal analysis and the next step is performing dynamic buckling with force impulse. In order to perform this analysis I need to apply an imperfection of the geometry (initial deformation). The imperfection is supposed to be the first buckling mode from static buckling and the corresponding displacements are assumed as a coefficient 0.01, 0.05 etc. Therefore my question is whether it is possible to apply such buckling mode imperfection in OptiStruct, if so where I can find this option?

 

Thank you for any help in advance.

Simon Križnik

Hi,

buckling instability causes convergence difficulties for implicit methods. Therefore I suggest using Radioss explicit solver instead following this procedure:
1.perform modal analysis in Optistruct
2.in postprocessing create a derived load case>linear superposition>use small scale factor (1e-2 to 1e-3)

3.export the deformed shaped.

4. import the deformed shape into Hypermesh Radioss user profile and set up non-linear buckling analysis.

 

By using the deformed shape obtained from the modal analysis the structure will have geometry imperfection triggering a buckling pattern consistent with modal and linear buckling analysis.

 

Note:1D element idealization will not capture the true buckling behavior of the thin-walled structure. Therefore 2D shell elements should be used instead.