General Mechanical

Propeller shaft induced vibrations analysis

• Luis
Subscriber

Hello everyone,

I'd like to set a mechanical simulation of a rotating (540rpm) propeller shaft of a ship: my aim is to analyze the stress induced by the vibrations to the strut that bears the bushing in which rotates the shaft. How can be done that? Which is the analysis system set that most fits to my case?

Luis

• Sandeep Medikonda
Ansys Employee

Luis,

You can either do a transient structural or a Harmonic response analysis. Please check out the following resources for some info:

Resource 1

Resource 2

Resource 3

Regards,
Sandeep
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• Luis
Subscriber

SandeepMedikonda thank you for your reply. So, in case of transient structural, I should just set a rotational velocity (from "inertial" menu) to my shaft and then check for the stress ? In case of Harmonic response analysis, the path is doing a static structural analysis (in which I set the rotational velocity), then a modal analysis (using as "pre stress" the previous static analysis) and then set the Harmonic response? Am I right?

Regards

Luis

• Sandeep Medikonda
Ansys Employee

Hi Luis,

Yes, see in that example that was shared we had a gravitational load which was done in static. You can just do a harmonic analysis if you want to set up a frequency load or a modal analysis if you want to just look at the natural frequencies.

Note that both modal and harmonic analysis are linear analysis and you are limited in terms of the contacts and materials you can use.

Regards,
Sandeep
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• Luis
Subscriber
Thank you so much for your help! About the rotor dynamics option, is the setting "coriolis effect" to be on or off (as default) ? Thanks
• Sandeep Medikonda
Ansys Employee

Luis,

"Coriolis effect" will account for the "damping” matrix contribution to the equations of the motion due to the rotation of the structure. You might want to keep that for a more accurate simulation.

Take a moment to read this section from the help.

Regards,
Sandeep
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• Luis
Subscriber
Is it to be active for both structural and modal analysis? (since I have linked them in order to take in account the stress from rotational velocity). Thanks, yes as soon as possible I will read it. Thank you again
• Sandeep Medikonda
Ansys Employee

Yes, use it in both:

Analysis Types Supported

The following analysis types support rotating structure analysis using a stationary reference frame:

• Static (ANTYPE, STATIC)

Quasi-static analysis is used to obtain the displacements and stresses of the structure subjected to the gyroscopic moment.

• Modal (ANTYPE,MODAL)

• Linear transient (ANTYPE,TRANS)

For a transient analysis involving a rotating structure with a stationary reference frame, support for a start or stop simulation is available. Issue the KBC command to ramp the rotational velocity.

• Harmonic (ANTYPE,HARMIC)

To include unbalance or general asynchronous rotating forces in a harmonic analysis, use the SYNCHRO command.

• Luis
Subscriber
thank you very much