I have calculated a pre-deformed structure according to the second-order analysis with RF‑STABILITY and RF‑IMP. Why are the deformations of the CO smaller than the applied pre-deformation?

Answer

In RF‑IMP, you have selected the "Generate pre-deformed FE mesh" option. In this case, the imperfect structure is considered in the calculation by using the deformed FE mesh generated in RF‑IMP. Thus, the CO results refer to the coordinates of the pre-deformed FE mesh and not to the original position in the perfect system.

To better explain this issue, I exported the coordinates of the pre-deformed FE mesh nodes from RF‑IMP to Excel. Based on this information, an imperfect structure was created in a new RFEM file and calculated according to the second-order analysis. The left window shows the deformation of the perfect structure considering RF‑STABILITY and RF‑IMP, and the right window shows the result of the imperfect structure. The results are identical.

Keywords

Deformation Imperfection Pre-deformation Result

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RFEM Main Program
RFEM 5.xx

Main Program

Structural engineering software for finite element analysis (FEA) of planar and spatial structural systems consisting of plates, walls, shells, members (beams), solids and contact elements

Price of First License
3,540.00 USD
RFEM Other
RF-IMP 5.xx

Add-on Module

Generation of equivalent geometric imperfections and pre-deformed initial structures for nonlinear calculations

Price of First License
760.00 USD
RFEM Other
RF-STABILITY 5.xx

Add-on Module

Stability analysis according to the eigenvalue method

Price of First License
1,030.00 USD