×
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 Response PSD Output Incorrect

Random Response PSD Output Incorrect

Random Response PSD Output Incorrect

(OP)
Dear all,

I am using Femap as pre/post-processor and MSC Nastran as solver for a random response analysis to study PSD response at certain locations.

However, the PSD response results on certain areas seem to be incorrect/unrealistic.

The whole response output spectrum is lower then input spectrum by an order of magnitude at certain node locations. I have tried this on the Femap default random response example (hingemodel), I can re-create the result given in documentation (on Node 44), however if in the same model I post process some other nodes, I get the same issue in PSD response output. I have attached the result plots for readers to look clearly.

(Please note, the discrepancy due to acceleration unit and output (use of scale factor), I have already take care of it, so that is not the issue).

I have uploaded the result. Anyone who has done Femap example can see the result on Node 44 is as given in the documentation. Node 289 is the input one, which is also correct. Additionally I am post-processing two other node locations (Node 130 and 118) and you can clearly see that they have the same behavior but they are lower than the input by orders of magnitude!. There is something wrong. I have tried different models and methods and I get the same result.

Does anyone have similar experience or any experience person can guide me what can actually be going wrong?

I'll be thankful, because I am quite stuck at this in work. Thanks in advance.

Umer

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