my system has a modal vibration mode 3.1Hz. So i have to chasge system to have a mode higher than 4Hz.
I can't insert a guide because the vibration mode is in a location where i have an huge displacement (a branch at the end of a veery long hot main header).

i thought to use a snubber.

Do i insert snubber only in dynamic input or have i to model both in static input both in dynamic input?

View the animation of the 3.1hz mode of vibration. See if there are any locations of significant displacement where you could add a restraint. Any restraint at a (displacement) high point will kill the mode.

i can't insert a restraint where is needed. the only solution maybe is a snubber. so the question remain open: i have to insert the snubber only in dynamic input or also (only) in static input? what does change inserting it or not in static input?

Have you considered adding a loop to avoid a snubber?

Have you given any thought as to how you might specify such a snubber?

Michael makes some good points to consider.

However, to answer your question, you can define the snubber either in the model itself, or in the dynamic input - BUT NOT BOTH. If you put the snubber in the model, it will only be considered in a static analysis if the load case is OCC and/or you check the "activate snubbers" checkbox in the Static Load Case Editor.

Snubbers will always be considered in a dynamic analysis.

thank you. better inserting in static imput or i can forget they are there

note: i solved the problem changing pipe routing (client didn't want but at the end they unserstood it was cheaper and better than using a snubber), but i had that question the answer will be ususeful if in future i will use a snubber