## General Mechanical

Topics relate to Mechanical Enterprise, Motion, Additive Print and more

#### MSUP harmonic analysis-rotordynamics

• Samuele Luigetti
Subscriber

Hello,

using MSUP method for harmonic analysis of a rotating structure, the gyrioscopic effect are considered? Since it's not possible to set Coriolis effect ON in MSUP analysis.

• Dave Looman
Ansys Employee

Example 7.4 in the APDL Rotordynamics Guide is a mode-sup harmonic with coriolis on in just the modal.

• Samuele Luigetti
Subscriber

yes, i have also coriolis on in the linked modal, but this is only to consider the changing in natural frequencies value. My suspect is that the harmonic consider that frequency constant, not variable with the rotational velocity (i.e. the sweep frequency)

• Dave Looman
Ansys Employee

Yes, if you are solving for a frequency range, the coriolis effect won't be adjusted based on the frequency.  That's an APDL limitation of the SYNCHRO command.

• Samuele Luigetti
Subscriber

ok thanks, anyway i'm working on workbench but i think it's the same. So, what do you suggest to take the coriolis effect into account for harmonic (except the full method)?

• Dave Looman
Ansys Employee

I don't see an alternative to using the full method.  Any reason not to use the full method?

• Samuele Luigetti
Subscriber

It's a bit complicated,, but i try to explain. The fact is that i have frequency of load different respect rotational velocity. So in the MSUP i set the sweep frequency equal to rotational velocity multiplied by ratio ( where ratio Fr load/Fr rotation), and the analysis take into account the natural frequencies of the linked modal with certain rotational velocity and then in post processing i correct all with the campbell diagram (beacuse the frequency response are not correct due to te fact that the coriolis effect are not take into account). With the full i cannot do this because there is not a linked modal so there's not some natural frequencies referred to a certain velocity (meanwhile in the other case yes). The perfect case would be an harmonic analysis that take into account the coriolis effect and with the possiblity at the same time to have different frequency between load and velocity, but i do not think that's exist.