Mass Properties with regards to hidden bodies

[rhobere]

Hello all. I've been lurking on the forum and using NX 7.5 for only about six months now, but this is the first question I've had to ask. My question is whether or not hidden bodies will contribute to the overall mass of a part. To clarify, I'm designing a part that will be tested under three different mounting configurations. As of now, I drew all three in one solid model and just assigned each body to different layers/different reference sets. If I "install" this part onto an assembly and perform a mass analysis on the assembly, will it use the mass of just the displayed body or will it include bodies on hidden layers or reference sets that are not shown?

Thanks in Advance.

 

[kapmnit123]

Hi,
Anything that comes in the MODEL REFERENCE set is counted for mass.(irrespective of if it is visible or hidden).
So remove the bodies from model ref set if you do not wish to count it for mass.
Regards
Kapil Sharma

 

[cowski]

I think the answer depends on how you are performing the mass analysis on the assembly.
Are you using "measure bodies", "advanced weight management", or another method?

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[rhobere]

I'm not the one doing the mass analysis. I'm simply defining one part on a much much larger assembly. I'll assume they're going to be using the Advanced Weight Management tool just because of the complexity of the model.

Thank you for the quick responses.

 

[JohnRBaker]

'Advanced Weight Management' does not necessarily mean that it would be used for complex models. Rather the 'Advanced' tile refers to having additional tools to do things like asserting the weight of things like models of purchased items where you know the weight from the vendor's catalog. Or to set limits so that if while working on a model or assembly, a predefined weight limit was exceeded you would be notified. Or where you might have an assembly where you might have a vaer accurately modeled solid model which when analyzed gives you the correct weight, but which you need to use a simplified Reference Set in the Assembly itself. This way you can direct the system, when it generates the mass properties of the Assembly to use the bodies in a specific Reference Set even if a different Reference Set was used in the Assembly. This will allow you to do things like substitute either empty or very simple representations of Components in an Assembly, maybe just a point or a few 2D/3D curves rather than even a simplified solid.

John R. Baker, P.E.
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To an Engineer, the glass is twice as big as it needs to be.

 

[cowski]

In the weight management dialog box you can specify which reference set to use for the weight calculation. It probably uses the model ref set by default as mentioned by Kapil.

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