I am trying to calculate COG of my assembly but the option Tools>Mass Properties>Mesh Properties only gives me the COG when structured mass is included. I want to add NSM and then calculate my COG.
Is there a way that can be done?
Unfortunately, you cannot assign NSM to Solid Element Properties.
As an alternative, for coatings, you can place shell elements with a very low stiffness and zero density and assign the NSM value to the shell property. You could also use Mass Elements attached to the solids using RBE3 elements that do not add stiffeness.
As an add-on to great Chip comments, the problem here is not related with FEMAP, but NX NASTRAN.
According the NX NASTRAN Quick Reference Guide (QRG) for the NSM, NSM1, NSML, and NSML1 nastran entries the properties you can use are PBAR, PBARL, PBEAM, PBEAML, PBCOMP, PCOMP, PCOMPG, PROD, CONROD, PBEND, PSHEAR, PSHELL, PTUBE, and PRAC2D.
Then as you can see, applying the NonStructural Mass Regions to the faces of solid elements is not supported by NX Nastran, therefore FEMAP do not include it in the calculation of Mass Properties and Center of Gravity of solids, OK?.
For workarounds, the coating technique is my recommendation.
Hello Blas and Chip,
I tried adding mass elements to the assembly using RBE3 and when I checked under Tools>Mass properties>mesh property, it still shows me only structural mass included with an added mass which is from mass elements and no NSM.
Does it mean that these mass elements add stiffness to my assembly since they are mentioned under structural mass?
Hi Blas and Chip,
One more question, if the NX Nastran does not allow us to add NSM to solid elements for calculation of COG, is it possible that it takes the NSM applied for solid elements through connection command during analysis?
I tried applying NSM through connect>Non-structural mass region
The highlighted is the NSM created with connection command and the other two are mass elements.
As said Non Structural Mass (NSM) is not supported by solid element faces, then either you use a coating mesh with shell elements, or use concentrated mass elements CONM2.