Inventor 2013 - negative material mass to calculate buoyancy

[Anonymous]

I have a customer who uses negative material mass in Inventor to calculate buoyancy for submerged constructions. After upgrading to 2013, we have a problem: Inventor 2013 does not accept negative material mass 

Any suggestions?

[Daniela_Koloszko]

Please see this post:

http://forums.autodesk.com/t5/Autodesk-Inventor/Negative-mass-calculation-in-Inventor-2013/m-p/37088...

[Anonymous]

The negative density is set using the material properties.

[Daniela_Koloszko]

The current Inventor 2013 behavior is correct. Inventor uses Protein Library from Inventor 2013 and it doesn’t accept a negative density. That’s why negative density doesn’t work.

As for workaround, you can "Disable" protein library temporarily. You can do it in the following way:

• Rename the folder name of “C:\Users\Public\Documents\Autodesk\Inventor 2013\Design Data\Materials”
• Rename the folder name of “C:\Program Files (x86)\Common Files\Autodesk Shared\Materials\2013”

If you need to have a “negative mass”, you can also override the mass with negative value for your calculation in this case. This is possble both via UI (iproperties dialog box) and API(MassProperties.Mass).