Combine Random vibration and functional loads FEMAP 10.2 (Nastran) 1

[JaviSanchez]

Hi everybody

Here I come with an easy one. I think my case must be so typical.
I need to combine random vibration and other functional loads (bolts preloads and pressure loads)in a model. I know how to combine functional loads but I don't know how to porceed with random vibration, in order to combine it with other static loads.

Thanks in advance.

 

[izax1]

As far as I know, you can only combine the responses. Maybe you also need to consider static preloading in the dynamic analysis.

 

[BlasMolero]

Dear Javi,
Well, in FEMAP you can make any combination you like based in the results output sets, you can use "Model > Output > Process" to copy, combine, envelope and convert any existing output, being static or dynamic.

In order to perform a randoum vibration, you need to define the excitation, for instance a function of the applied PSD power spectral density (autospectra of base excitation) using the Model > Function menu selecting Type=3..vs.Frequency. Take a look to the tutorials of FEMAP & NX NASTRAN.

Best regards,
Blas.

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Blas Molero Hidalgo
Ingeniero Industrial
Director

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[JaviSanchez]

Hi

I found this paper with a explanation about how to perform random analysis of pre-stressed structures in MSC/Nastran.

http://www.mscsoftware.com/support/library/conf/auc99/p05199.pdf