Learning Forum

[dmg15]

I had a question regarding center of mass and moment of inertir. The fact is that I have built a model to perform a modal analysis, where I have a surfeca and distributed masses. The problem is that I would like to know its center of mass and moments of inertia, but if I select the surface and view its properties, the distributed masses, which are affecting the center of mass and inertia of the model, are not taken into account. I know that when you have multiple bodies, the solution is to build a common part in DM and then view the properties of the part and you will get the proper center of mass and inertias, but with distributed masses this is not possible. Any suggestions?

[mrife]

The distributed mass is not an CAD object in Mechanical - it really gets defined in the model when the solver input file is created. When solving the mass summary is given at the start of the actual FEA equation solving step. You can find this in the Solution Information. This has the benefit of being the FEM mass and not the CAD mass. Suppress all the parts except those you want the center of mass etc. Add a boundary condition and fix all bodies to have zero displacement. Add a empty Commands object (so Mechanical thinks there is a load) and solve. Then view the Solution Information use the ctrl-f to bring up the find tool. Search for the word PRECISE and check on the Match Case box. It should take you to the precise mass listing and the center of mass etc is given there.
Mike

[dmg15]

Thanks for the answer