1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Rayleigh Ritz method to find natural frequencies

  1. Dec 19, 2016 #1
    Hello everyone,

    I have found an old finite element exam question in which you have to use Rayleigh Ritz method to find natural frequencies of a system. The displacement field is given as u(x,t) = q1(t)x. I'm confused as I thought that the equation U = 0.5∫ EI u''2 dx would be used (as part of the method for finding the answer) but differentiating q1(t)x twice will give 0. Am I approaching this problem is totally the wrong way?

    Thanks very much!

    FYI: The way I am thinking about going about this question is to use U = 0.5∫ EI u''2 dx and T = 0.5∫ m dx u°2 (where u° is the first time derivative) and then frequency2 = U/T
  2. jcsd
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Can you offer guidance or do you also need help?
Draft saved Draft deleted