Body mass modification in Mechanical ACT

Pavel Member Posts: 9
5 Likes Name Dropper First Answer Photogenic
edited June 2023 in Structures

(I was about to drop this in SR but maybe it will be more useful in this public space.)

We have a need for modifying mass of bodies in Mechanical. That is: mass that doesn't match the material density*volume.

So my question is whether there is some way to implement this either natively (enhancement request) or using ACT? The closets I can think of is:

  1. making a copy of given material (System's Engineering Data) for all target bodies
  2. Calculate target density and change it in the copied materials
  3. Assign the copied materials to those scoped bodies.

Things get more complicated with multiple materials involved with multiple bodies but that's just mathematical and results with more material duplicates. This is ok solution but I'd like to hear from you whether you have some better idea to achieve this.


We don't find these handy but adding for context of what we've considered or even implemented

  • Previously we employed APDL and made ACT object wrapper for the APDL code but one big drawback is that we don't get to see that change inside Mechanical. Additionally I'm not sure how well this works when combining systems into assemblies (connecting more Systems into another).
  • The native option right now is to use distributed mass but it has 2 issues: 1 - the added mass does not appear in selection information panel, 2 - cannot have negative mass (e.g. cannot set body mass to less than it was), 3 - distribution is not homogenous since only surfaces are used, not to mention the added surface elements to the solution.

Best Answer

  • Pierre Thieffry
    Pierre Thieffry Member, Moderator, Employee Posts: 91
    First Anniversary Ansys Employee Solution Developer Community of Practice Member Photogenic
    Answer ✓

    Hi @Pavel , sounds familiar :-) I think your proposed solution with duplicating material models is the right one. You will have a hard time to reduce the mass otherwise (of course APDL tweaks like you did work as well but yes, you can't check prior to solving and commands may get lost in assemblies).