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Homework Help: Relating pavement roughness in frequency to displacement

  1. Aug 9, 2015 #1
    Hi all,

    I'm attempting to optimise a suspension system's spring and damping rate via vibrational analysis.
    Working in the frequency domain, I have calculated the input-output relationship as a ratio (i.e. ground to body, x/q2 in the attachment) and the mean square acceleration response based on an input modelled using an exponential power spectral density.

    From here I want to calculate the corresponding stroke of the suspension components and the separation between the road and the suspension system as a measure of road adhesion. My intention is to optimise the k and c values based on these three measures.

    So what I'm asking is how do I relate the frequencies I've used in my MSAR calculation to the change in vertical height of the road or vice versa? Or am I going about this in the wrong way?

    Attached is the half car model I'm using and the key equations along with my rough spreadsheet used for calculations.

    Thanks in advance.

    Attached Files:

  2. jcsd
  3. Aug 10, 2015 #2


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  4. Aug 10, 2015 #3
    Thanks for the reply. Perhaps I need to be a bit more specific.

    What I'm after is a way of finding q2 or x for a given frequency. So would it be valid to divide the Mean Square Acceleration Response by -omega^2 to get the displacement? I.e. x(f).

    I have delved into a considerable amount of the literature but I can't find an adequate answer.
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