×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Natural frequency of turbine rotor

Natural frequency of turbine rotor

Natural frequency of turbine rotor

(OP)
I get peculiar results from turbine rotor. Adding constraints to bearing locations lowers natural frequencies. Higher frequencies with no constraints comparing to same mode shapes as in constrained model. No damping included at bearing locations. Beam and shell elements are used. Adding any constraints should add onto natural frequencies, right?

Thanks a bunch

RE: Natural frequency of turbine rotor

Are any of the bearing locations hollow shafts modeled with shell elements, and constrained at a single node on the OD?
I was getting some unrealistic results from deflections at the bearing locations that looked kind of like this C>.  Kind of like a tent pole poking a very localized high spot.

With my shaft modeling I started using 2 pairs of spring elements attached tangentially at the neutral axis OD. 4 springs = one bearing.  This is probably somewhat stiffer than a real bearing, but I got pretty good results with it.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources