×
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

Modal identification using Frecuency domain descomposition

Modal identification using Frecuency domain descomposition

Modal identification using Frecuency domain descomposition

(OP)
Hello, I´m spanish, my english is very bad...
I try to make a program that use the method "frequency domain descomposition" (FDD) (Brincker et al. (2000)).
I try to calculate the modal parameters of a cantilever beam. This method take n-signal and make the spectral density matrix. Then compute the singular value descomposition (SVD) for each frequency and take for a new approximation, for the frequency response of my mechanical system, the maximum singular value of each frequency. The eigenvector at the natural frequency is the shape mode, and the damping ratio is estimated from the inverse fft of the svd around the peak of the natural frequency.

I have a problem to calculate the PSD of each signal. I´m usin the command pwelch of MATLAB, that use the welch's method to estimate de PSD. The parameters of this command are the length of the window to average, the overlap of these windows and the number of samples that I anlyze.  I see that the spectrum's amplitude and shape change with the value of the length window.

Someone could help me.
Thanks!

RE: Modal identification using Frecuency domain descomposition

This question belongs in the Mechanical engineering other topics, or Finite element analysis engineering or Programming language engineering

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