Erik Kostson
Ansys Employee

In your initial question you pulled it up (that is what you mean with initial displ. you said) and you release to see the free vibration. That was a transient analysis as it is a transient event (pull and release, followed by free vibration).

Now if you have a harmonic event like say we move the fixed end of the beam up and down with a sinusoidal displacement then we can use a frequency domain harmonic structural response. We have a course on that, so you can see how it is done.

All the best