Q: How can I get statistics in the time domain of the force produced by a #DRAG load attribute?
REV 5.06

A: The basic idea behind MOSES is that one models "things" and these "things" always effect the behavior of the system. Even Tanaka roll damping effects roll in a time domain simulation. As a rule, unless we say it does not work explicitly, it works all the time.

Now, obtaining the variation of force with time is accomplished via post-processing. We do not store the forces on each item as a function of time since it would be highly inefficient. Instead, there are two commands, ELMFORCE and LDGFORCE which recompute the forces on beam elements and load groups and make these available in the Disposition Menu. Here, you can get the statistics.

Also, when I am in doubt as to how something works, I normally build a simple test to see for myself. For example:

The Data file

     &describe body box

     pgen

       plane 0 100 -rect 0 20 50

     end

     &describe load damp

     *cen 50 0 5

     #drag *cen .064*100*10*50 1

The Data file

     inmodel

     &instate -loc 0 0 -10

     &weight -compute 5 32 29 29

     &instate -vel 10

     &apply damp 0

     &loop i ( 1 2 )

       &status loadg_mult

       tdom -tstep .25 -maxt 10

       prcpost

           traj

               report loc vel

               end

       end

       &apply damp 100

     &endloop

     &FINI

would have told you quite a bit about how this works in the time domain. In particular, it does two time domains, one with and one without the #DRAG so you can easily see the difference.