You need a DLOAD case control to select the dynamic load. The SID specified in case control can directly reference the TLOADi bulk data entry.
The TLOADi entry then specifies the type of excitation (Load or enforced displacement/velocity/acceleration), gives reference to a TABLEDi field that specifies time vs. scale factor, and an EXCITEID. Any load entries (i.e. FORCE, PLOAD, etc.) that have an SID matching the EXCITEID on a TLOADi will have their magnitudes scaled with time accoring to the TABLEDi data.
Thanks for the reply, but how do I do all that? Right-click on the Solution, then Edit..., then Case Control or Bulk data?. I don't know how to do that. Can you explain it to me in little steps, please?
Sorry. You posted the question in the NX Nastran forum, so I answered in terms of Nastran. If you want to know how to set this up in NX, the post should really be in the NX CAE forum.
What version of NX are you running, and what type of solution are you setting up?