Polar Moment of Inertia in NX7

[kkaldor]

I am trying to figure out a polar moment of inertia in NX7 of a hollow section. In the Analysis->Section Inertia menu, it states the section type as Hollow and to specify a "Hollow Thickness". I don't understand what this "Hollow Thickness" is referring to. If I change the value, it changes my result.

I am used to the program (Pro/E) solving this for me and not having to specify anything but a cross section. Can anyone help me out? This is what my part looks like. I'm trying to get the polar moment of interia with respect to the left vertical edge, in the x-axis.

 

[JohnRBaker]

You're misunderstanding the use of the term 'Hollow' for the 'Section Type'. In your example, despite the face that it has an internal 'void', it is is NOT 'Hollow' for purposes of this analysis. Change this setting to 'Solid' and ignore the value for 'Hollow Thickness'.

The 'Hollow' option is for those situations where your profile consists of only curves and you're using the 'Existing Section' type of analysis. This is intended for when the existing 'section' of curves represents the cross-section of a thin-walled body, like a piece of ductwork or other sheetmetal part.

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
Siemens PLM:
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To an Engineer, the glass is twice as big as it needs to be.

 

[kkaldor]

John,

Thanks for the response. I have tried using the "solid" section type, but it just gives me a warning when I click OK or Apply that says "Due to open sections, hollow analysis is used". Any suggestions?

Thanks

 

[JohnRBaker]

Without seeing your model I couldn't comment on this since the image that you posted appears to represent the cross section of a SOLID body.

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.