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Random response Analysis RANDPS

User: "ManishKanwal"
ManishKanwal
Altair Community Member

Hello all ,

I am performing a Random response analysis and I have a question regarding the keyword RANDPS. What does J & K represent there?

Does K represents the PSD at the source of vibration and J represents the PSD where the vibration is measured?

Thanks!

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    User: "solon"
    solon
    Altair Employee

    Hello,

    The RANDPS card defines the load set power spectral density factors for use in random analysis having the frequency dependent form : Sjk(Ω)=(X+iY)G(Ω). The J and K entries determine whether the PSD is of auto correlation or cross correlation function and X and Y entries are the components of complex numbers, which means they are the real and imaginary parts and usually represent Cross-Spectrum PSD.

    For auto spectral density / Uncoupled PSDF, J = K, scaling from real-valued X will be greater than zero and Y must be equal to zero.

    For cross spectral density / Coupled PSDF (input from 2 sources), J will not be equal to K, and both X and Y can be specified. The Cross-PSD will be a product of a frequency-independent complex value (X+iY) and a frequency-dependent scalar function (G).

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