Elastic and Elastic-plastic Shear Buckling of plates with initial imperfection
(sorry for my eng) I am performing a model of pure shear in plates with different thickness for capture both types of buckling. The different plates are squares of 1[m] of length. This procedure is make in three stages
* Static structural analysis (1): Defining border conditions and lateral loads of magnitude 1 using an elastic steel (structural steel)
* EigenValue Buckling: for obtain the magnitud of elastic buckling loads
* Static structural analysis (2): Same model with Bilinear isotropic hardening for the steel Fy 250 [MPa], large deflections on, initial imperfection associated with the first buckling mode and the loads with the magnitud obtain previously are applied incrementally in 100 steps.
I do this procedure for ten different thickness from 2[mm] to 9[mm] then I draw the force vs displacement. My problem is that for small thicknesses (elastic buckling) the plate does not fail at the elastic limit and exceeds this value while for greater thicknesses (elastic plastic buckling) it does have an asymptotic behavior towards the elastic plastic buckling load having good results.
The element used in this analysis is Shell281.
note: (in the analysis with thinner plates I also used bigger values of Fy because workbench it wont let me use a perfect elastic material for the second static structural analysis)