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