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Remote mass counted twice?

Question asked by Steve McCallion on Jul 1, 2016
Latest reply on Jul 5, 2016 by Steve McCallion

My coworker and I are performing harmonic and linear dynamic studies on a system.

What we're doing right now is checking how much mass is actually in the FEM model. It's a fairly complex model with a mixture of elements and external masses so we're relying on the MASS MOMENT INFORMATION in the .OUT file to give us this information.


When reading the .OUT file we noticed that the mass seems a bit too much. Thus we've done some testing:

Total mass of applied remote masses = 3kg

Total mass of system reported in .OUT file = 16kg

Suppress remote masses, .OUT file reports exactly 10kg i.e. twice the mass of the remote masses (6kg) has disappeared, instead of the expected 3kg.


We set up a simple test to check this. A cube of aluminium, with a remote mass attached to it. Same result. The .OUT file is reporting the total mass as the cube of aluminium plus twice the external mass.

It does not do this if we change the Remote Mass to a Distributed Mass.


Has anyone else noticed this, and come to the conclusion that the .OUT file is just adding up the mass and reporting it incorrectly?

Indirectly related, I've done tests previously to look at how different bodies with different mass distributions behave compared to remote masses, and don't believe it's applying the external masses in the simulation incorrectly. Just that it's doing some post-processing incorrectly.


One last question, is there anyway of getting the mass of a model without running a ful simulation?