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Author Topic: Mass Discrepancies  (Read 25126 times)

James.rogers@nasa.gov

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Mass Discrepancies
« on: July 19, 2019, 02:39:06 PM »
When sizing components with the "Hat Bonded" concept, there is a discrepancy between the mass of the component displayed within Hypersizer and the bdf/f06 files created when using the "Update Nastran" button. With each iteration performed, the component mass within the updated bdf/f06 is further increased by the original amount of mass for the given component.

I have not encountered this issue with the "One Stack Unstiffened" or the "Honeycomb Sandwich" concepts.

James

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Re: Mass Discrepancies
« Reply #1 on: July 19, 2019, 02:42:46 PM »
This likely has to do with non-structural mass (NSM). For smeared panels, HyperSizer uses the NSM field on the PSHELL card to represent the mass of the panel. Two things could be causing this..
 1. Incorrect mass units (lbm instead of slinches)
 2. Added weight, imported from NSM of original model. The "added weight" on the options tab is included in the NSM for the PSHELL.

I hope this is helpful.

-James

James.rogers@nasa.gov

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Re: Mass Discrepancies
« Reply #2 on: July 19, 2019, 04:36:59 PM »
To clarify, for the second option you mentioned, are you suggesting that I modify my import/export options within the "project setup" window?

James

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Re: Mass Discrepancies
« Reply #3 on: July 19, 2019, 04:40:30 PM »
Did you have NSM in your model? Do you see any 'added weight' reported on the options tab?

For future projects, before importing the FEM, deactivate the import/export option that prompts HyperSizer to import and store NSM.

To fix this project you can clear the added weight from the options tab, right-click and apply to all components in the project.

-James