Stiffness not changed for Buckling Constraint

[JanPio]

Hi,
I try to implement buckling constraint of 1 into my analysis.
My settings:

• Failure analyses: only stiffness requirements
• ABD components: all D_ij (also tested with all A_ij and all D_ij, same problem)
• one buckling load case from ANSYS
• panels in the region where buckling occurs first are "one stack unstiffened" starting at 2mm thickness, Max bound is sufficiently high
• all elements are in a common display set that is selected for the constraint
• FEA loads extraction: peak element filtered (if this makes a difference for FEA constraints)

Working:

• Mode shape displayed in FEM Viewer
• correct Eigenvalue displayed in FEM Viewer
• max translation of 1 displayed in FEM Viewer
• iterations run without error
• buckling contraints, lambda_actual, lambda_req and the factor are shown in the iteration report
• the thickness is increased once from 2 to 3 mm

However, the factor does not seem to be correctly translated into required stiffnesses of the panel (see table below).
Not working:

• the thickness is not further increased
• all component factors for stiffness are =1 (see table below)
• all margins of safety are (slightly) positive (probably because the required stiffness matches the actual stiffness in the table)
• there is no Mode Detection Parameter higher than the order of E-31, which seems very low to me

      

lambda limit	lambda actual	Factor
1	0.002128684	469.7737189

D11	D11,req Current	D11,req Next	Factor
181121.4823	181121.4823	181121.4823	1

Do you know why the obviously high "Factor" does not lead to further panel thickening?
Thanks,
Jan