Is it possible to override mass in NX? 3

[JavadM]

Hi friends.
i have to design a mechanism. i don't know about specific material but the mass for each components is given.
is there any way to specify custom mass for a part in NX instead of specifying certain material?

NX 12



regards

 

[JohnRBaker]

YES, under 'Weight Management' you can Assert such things as weight and mass as well as other properties such as COG, etc.

John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:

The secret of life is not finding someone to live with
It's finding someone you can't live without

 

[JavadM]

Hello dear john
thanks a lot.
i changed mass of a sample for test. in file properties asserted mass is as i want, but using measure command i see the exact amount for solid body.
i attached screen shot.

the mechanism should be later analyzed by motion simulation.
question pops is that "which one of these mass amounts is recognized by simcenter or motion simulation"?



sincerely
javad

 

[cowski]

I don't know enough about motion simulation and asserted weight values to answer your question, but I do have an alternative method:
Mass = Density * Volume
Use the measure body command to find the volume of your part; then using the equation above, you can solve for the density that would result in your desired weight
Density = Mass/Volume
Use menu -> edit -> feature -> solid density to assign the calculated density to the solid body. Now the measure body command will return the desired mass value and it will return correct mass properties (COG, inertia values, etc) assuming the real part is of uniform density.

www.nxjournaling.com

 

[JavadM]

hi cowski

amazing method.you saved me
also it will be possible to create an intermediate material with this calculated density for motion simulation application.


thanks a lot

 

[MikeHyde]

Just to explain the differences in the methods - Assert Mass acts on the part but does not change the mass of the bodies. We use this for black-box items to set the mass and COG for the vehicle weight roll-up where we only need it to be correct at part level.

Cowski's method acts on the individual bodies which is better for your requirements.

Mike Hyde
NX12.0.0 with TC11.3 and Vis 11.3

 

[Xwheelguy]

If you're only concerned about mass, then cowski's method will work just fine.

However, you can also create a Local Material (Tools -> Materials -> Manage Materials) and enter the density value for a Local Material (a User Defined Material, more or less) which should be able to be copied from part to part. The difference is you can also control more than mass (mechanical properties, thermal, etc.) in case you're going to use this model downstream in some NX analysis application (for the motion simulation). I've quit using Edit Solid Density altogether for mass - assigning materials is more informative and allows you to make notes and actually label the material to give other users the info they may need or know where the density value came from (as they can differ from spec to spec for certain materials) and you can't plug that info into the model density alone.

If you're not going to use all the other Material property entries, just ignore them and focus on the Density value.

Tim Flater
NX Designer
NX 11.0.1.11 MP8
GM GPDL 11-A.3.3
Win7 Enterprise x64 SP1
Intel Core i7 2.5GHz 16GB RAM
4GB NVIDIA Quadro K3100M

 

[Toost]

If your parts , or some of your parts, in an assembly has asserted values, you MUST use the weight management - calculate to get correct weight of your assemblies.
The "measure bodies" does NOT bother about asserted values.
i have not tried the NX12 "measure" feature. yet.
I do not know if the different simulations care about the asserted values.


Regards,
Tomas

 

[Toost]

Oops, seems that the asserted Weight now also populates the "file" ( See assembly navigator) in case one has the customer default Generate weight data set under Analysis - Weight management,
I think that it did not in previous releases.


Regards,
Tomas

 

[JavadM]

Hi again
thanks for sharing your experiences.
as it seems motion application don't cares about asserted mass. links mass is what measure tool displays.
this also can be seen in information window for each link in motion navigator.
so for these applications cowski and Tim methods works fine.


best regards
javad