Defining Damping for CMS — Lesson 7

Any guidance on how to define damping for CMS in RDB?

The attached example illustrates the setup (and exposes the damping as parameters)

On the Condensed Part, you can insert a command. Note that this command is typed with the solver target. MAPDL commands will be used by the generation pass, but RBD commands will be consumed by the use pass. So, insert an RBD command in which you retrieve the Condensed Part Id. The internal variable set by Ansys Mechanical™ structural finite element analysis software is _cpid and the comment doesn't say that. Note that this Id is also the same as the name of the folder used for the generation pass (cpxxxx)

Because multiple parts can be condensed together, there is a need to translate this _cpid into a solver CMS part id. This is done using the "FindCMSBodyByCondensedPartId" macro. This will return a CMS Part on which you can apply Alpha and Beta damping.

A few additional notes:
RBD now supports damping from the generation pass. The C reduced damping matrix produced by the generation pass is used in the use pass. Damping values can be defined in EDA.
AlphaDamping and BetaDamping are CS_Variable, not necessarily constant values. That means that this damping can be model state dependent.