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Author Topic: Beam orientations in non-global coordinates vs Grid reference  (Read 16606 times)

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Beam orientations in non-global coordinates vs Grid reference
« on: October 30, 2008, 11:57:35 AM »
I have a Nastran FEM of ring frame with CBAR and GRIDs defined in the cylindrical coordinate system. My orientation vector on the CBAR is -1./0./0. so the strong axis is pointing to the ring center.

However the loaded FEM in HyperSizer shows the orientation going in airplane axial direction (or Z in cyl coordinate system). I know that HyperSizer y and z are switched from Nastran (HyperSizer has strong axis in Z direction)

Question:
Do I have to provide the orientation vector in global coordinates as the only way?
Does HyperSizer support Nastran options of providing a beam orientation (by GRID point, by orientation vector), and does it take into account whether the GRID's analysis system is in a rectangular or cylindrical coordinate system?
« Last Edit: October 30, 2008, 12:00:55 PM by Phil »

Phil

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Re: Beam orientations in non-global coordinates vs Grid reference
« Reply #1 on: October 30, 2008, 12:00:30 PM »
I did verify that HyperSizer does not support beam orientations that are not in global coordinates.  The orientation vectors must be defined in global coordinates.

HyperSizer DOES correctly interpret beam orientations that are defined by a GRID reference.

By the way, even if HyperSizer does not correctly interpret the orientation, it will not affect the analysis or sizing if you use "neutral axis" reference plane on your beams on the Sizing Form | Options tab. In that case, there are no transformations to be done either on import of FEA loads or export to the FEM for iteration. If you use one of the other options (Beam Top or Beam Bottom), then the offset vectors exported by HyperSizer to the *.CL1 file will not be correct.