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?

In RF‑IMP, you have selected the "Generate pre-deformed FE mesh" option. In this case, the imperfect structure is considered in the calculation 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 explain this issue better, 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.