## General Mechanical

#### Elastic and Elastic-plastic Shear Buckling of plates with initial imperfection

• feliperignacio
Subscriber
Hello,n(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 n* Static structural analysis (1): Defining border conditions and lateral loads of magnitude 1 using an elastic steel (structural steel)n* EigenValue Buckling: for obtain the magnitud of elastic buckling loads n* 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. nI 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.nThe element used in this analysis is Shell281.nnote: (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) n
• feliperignacio
Subscriber
it is could be a problem of shear locking?n
• HuiLiu
Ansys Employee
Hi, I'm not entirely sure about your workflow, but it sounded like you are trying to find out the nonlinear buckling load and compare it with linear buckling? If that's the case, I wouldn't expect them to be the same. Typically if any nonlinearity exist in the model (in your case nonlinear material and large deflection), you can have the base static analysis solve as nonlinear, then do an eigenvalue buckling analysis based on that nonlinear base analysis. Did you try this approach? This should give you a more accurate buckling load for a nonlinear based eigenvalue buckling problem. nYou can take a look at this link for more details on linear vs nonlinear based eigenvalue buckling:https://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v202/en/wb_sim/ds_buckling_analysis_type.html?q=bucklingnn