FAQ 004412 | It is not possible to design a SHAPE‑THIN cross-section due to invalid symmetry. What is the cause and how can I fix it?

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05/04/2020

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Sonja von Bloh

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Question

It is not possible to design a SHAPE‑THIN cross-section due to invalid symmetry. What is the cause and how can I fix it?

Answer

RF-/ALUMINUM checks the symmetry of general cross-sections and compares them with the SHAPE-THIN evaluation if activating the "Determine symmetry by module and compare with SHAPE‑THIN definition" check box (Figure 01).

Figure 01 - Dialog Box Details, Check Box Symmetry

If both methods provide different results, the corresponding error message appears (Figure 02).

Figure 02 - Error message

Usually, there are small inaccuracies in the SHAPE‑THIN cross-section. Thus, the cross-section Sec‑1.du9 shown in Figure 03 is not absolutely symmetrical to the Z‑axis: The Z‑coordinates of Node 1 and Node 4 as well as Node 55 and Node 60 do not match in the second decimal place.

Figure 03 - Different Z-Coordinates of Cross-Section

SHAPE‑THIN classifies the cross-section as asymmetrical, but RF‑/ALUMINUM as monosymmetric to the z‑axis, so the error message shown in Figure 02 appears.

The SHAPE‑THIN cross-section should be checked for symmetry. When modeling in SHAPE‑THIN, it is useful to only display one side of the cross-section and to create the other half by mirroring. This is also shown in the video.

Keywords

Dlubal FAQ Failed design Symmetry Frequently Asked Question FAQ about Dlubal Question and Answer about Dlubal

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  • Updated 06/08/2020

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