Frequency Response and Random Response (Dynamic Response in Nastran)
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- Опубликовано: 4 июл 2024
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Thank you, Structures Aero!
Thank you very much for this video, it helped me understand PSD analysis quite a bit!
Great content. Keep it up!
Dang, how do I even still have a job when you've turned what I do into something so simple! haha. Great presentation.
Thank you Sir.
I was actually on the WFIRST program at Goddard a few months ago. What a small world.
Thanks for this example, I found it very useful. All of the random excitation examples I seen have a flat PSD for the input, which I suppose is essentially the definition of random. Supposing I want to use a PSD that is more peaky, ie it has peaks at harmonics of the machine operating speed - is the analysis still valid? For example are the 1-2-3-sigma percentage breakdowns still valid? Also, supposing I want to know the 0-sigma stress how do I find that value? One more question - if I have measured input PSDs in the X/Y/Z directions is it possible to apply a different PSD to each direction?
Hi,
In the Random PSD plot, in the out put is it possible to evaluate the G value (Gpeak) for a particular frequency. How can I do that? There different versions to find the Gpeak is floating around. I need to find the correct one. Thanks.
Great explanation but would have liked it more if cards were shown in text editor.
Interesting if the sound were not so distorted, words keep escaping my ears... recording sound thru a secondary connection instead of the original source is a terrible idea.
The input PSD you show at 34:58 doesnt match what you plot at 41:20. Do you know why? I appreciate your help.
I figured it out. From ---> community.plm.automation.siemens.com/t5/3D-Simulation-Femap-Forum/Random-Response-Analysis-ASD-Units/td-p/407823
"....For random response analysis, the loading is a unit acceleration( 1g) applied in the frequency response portion of the solution. If you want all of the response quantities(accel,force,stress etc) to have proper units, then this would 9.81m/sec^2
This means after scaling by the ASD, your acceleration results are actually (m/sec^2)^2, which may not be so handy to look at(since your input ASD is g^2/hz). But with Femap charting, you then scale the acceleration results back into g^2/hz by dividing by (9.81m/sec^2)^2
A good check to make is to always request accel response for your base drive node, it should match your input ASD if you are consistent with units. ..."
@@jrharrison3 thanks for letting others know what you figured out. 😃
When i tried to solve im getting FATAL Error please help me in this
USER FATAL MESSAGE 3046 (SQFREQ)
THIS FREQUENCY RESPONSE ANALYSIS HAS NO EXCITATION SPECIFIED FOR IT.
where to define a excitation
Hi, did you find the answer ?
Yes
Where can I download models? Thank you
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