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Matlab: transfer function determination

  1. Sep 1, 2010 #1
    I have a 2 dof vibration system, I have determined the differential equation of the model, can I determine the trasfer function readily with matlab, without using manual algebra operation?
    In other word, I have that differential equation system:


    [m] mass matrix
    [c] damping matrix
    [k] stiffness matrix
    [f] external forces matrix

    through laplace transformation I obtain:


    where s is the laplace variable, how can I find [f]/[x]?
    I'm searching a way for estimating readily the transfer function of mechanical system, it is a loss of time to perform the calculation every time
  2. jcsd
  3. Sep 7, 2010 #2
    may anyone help me?
  4. Sep 7, 2010 #3
    You've pretty much got the TF. Rearrange the laplace you've done above so you get f/x = tf (factorise the left side wrt to X). From there, you can use matlab to analyse the TF.
    MATLAB tools(look in help): tf, bode, ltview.
    The time required to manually calculate the TF is trivial for systems like this. You can use dsolve to get a symbolic solution to the ODE but it's not really necessary
  5. Oct 4, 2010 #4
    I know the tf, bode function, but how can I use them when the system has more than one dofs?
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