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NonStructural Mass Region

Pioneer
Pioneer

Hello all,

 

I want to apply a mass via NonStructural Mass Region. In a little video tutorial by Siemens it seemed pretty easy and I did it the same way, but now I can't see any effect of the mass in modal analysis or frequency response analysis.

Of course, the region is enabled. The number is so small because I use tons as unit.

 

What you see in the image is just an example modell. In my real modell I applied the mass using a RBE3 element, as NonStructural Mass Region doesn't work. But I want to avoid the RBE3 element because it increases the time my simulation needs (because it's quite big).

So it would be nice if somebody has a hint to make the NonStructural Mass Region work.

 

Thanks in advance

 

2018-03-02 12_19_30-Femap with NX Nastran - [balken_mass_region _ Untitled].png

5 REPLIES

Re: NonStructural Mass Region

Legend
Legend

Svede

 

I have never used the NS mass region, but I use another method to add NS mass to my models. It works best if you still have geometry and are able to split it, so that the mass is added to the areas you want.

 

- Create duplicate property for the mesh area you wish to add NS mass

- Update elements properties for this region and chose new property (this property should have a unit value of 1 in the NS mass)

- Run model mass check and reference NS mass value

- Divide this by the value you want and update your property.

- re run mass check.

 

NS_MASS.JPG

Re: NonStructural Mass Region

Siemens Legend Siemens Legend
Siemens Legend

@svede

Are those solid elements?

From the Nastran QRG:

NSM and NSM1

Type - Properties are: PBAR, PBARL, PBEAM, PBEAML, PBCOMP, PCOMP, PCOMPG, PROD, CONROD, PBEND, PSHEAR, PSHELL, PTUBE, and PRAC2D. ELEMENT list of individual element IDs of element that can have NSM. (Character)

Re: NonStructural Mass Region

Pioneer
Pioneer

@T_GiampietroYes they are solid elements, then that's why it isn't possible... Thanks for the advice!

 

@Stuart_Sgreat thank you! I will try out this method.

Re: NonStructural Mass Region

Legend
Legend
Svede

If your model is actually using solid elements the NS mass in the propery will not be available - but you could use:

MESH > Edge Members

To skin the solid elements and apply the NS mass to these shell element etc.

Re: NonStructural Mass Region

Pioneer
Pioneer

Nice, it worked! Thank you again very much!