Random response Analysis RANDPS

ManishKanwal

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!

solon

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).