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
Solved! Go to Solution.
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.
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)
See image below.
As per the discussion above, the user did not want to use RBE/mass element combination so the following work around can be used.
Simply supported beam example, modeled with Hex elements. First image is the beam bending due to self weight the second image is a distributed NS mass area. to achieve the NS mass area I used the command, MESH>EDGE ELEMENTS, this then takes me through a dialog box to select the existing elements I want to "skin". You can see the property setup - very thin thickness compared to the existing beam (5mm vs 0.01mm).
Note* there are many different ways to do this, for example just mesh the surfaces with the plate property and merge the nodes. I highlighted use of the edge elements incase the geometry was missing & it ensures the exact mesh.
Hope this helps