×
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

random vibration environment analysis

random vibration environment analysis

random vibration environment analysis

(OP)
Hello everyone,
could anyone plase tell me what is the correct procedure to perform a structural analysis by FEA on an item subjucted to random vibration? I work in aerospace field and use NX.Nastran with Femap. I know the input PSD for this item and I would like to verify its strength. It includes some welded connections also: how are they usually modelled?

Thanks and regards

RE: random vibration environment analysis

Random vibe is based on a natural frequency analysis, so you will need to run that first.  Set your model up with your realistic boundary conditions.  Input your PSD.  There are some other considerations, but I'm not familiar enough with NX to know what to tell you...

Garland E. Borowski, PE
Engineering Manager
Star Aviation

RE: random vibration environment analysis

You have to do a response simulation in NX.   In order to do this, you need to have the NASTRAN response simulation license.  Otherwise you are up the creek.   NX also has  the ability to perform the fatigue analysis.


The NX documentation should be able to give you all the information you need about setting up and running the models?

RE: random vibration environment analysis

(OP)
Hello,

I don't use NX but Nastran with Femap as pre-post, with the licence for dynamic analysis. I am able to perform freq response and to apply PSD, but I would like to know how to consider the results, since I can have PSD of component stresses, and not Von Mises. Is there any standard procedure?

 

RE: random vibration environment analysis

I don't know a whole lot about random vibration analysis, but don't you want to use RMS stress for fatigue evaluation?  The reason I ask is that I have a textbook that has an example of determining the fatigue life of a cantilever beam subject to random vibration.   The example uses the RMS bending stress to determine the fatigue life.

I know NASTRAN is capable of calculating the RMS VonMises Stress.   I can also get X-Y plots of the PSD of VonMises stresses for an individual element.
 

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