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Frequency response analysis using NASTRAN

Frequency response analysis using NASTRAN

Frequency response analysis using NASTRAN

(OP)
Hallo!
 I am running point mobility to find out the '0' Hz equivalnet static stiffness of bracketry of a typical SUV frame.Calculating the deflections and from deflections calculating the stiffness. Aim is to find out the equivalent static stiffness in a free-free conditions. But, I do nothave any tool or back ground to support my results. Can any body suggest a way for that.

Kamalakar

RE: Frequency response analysis using NASTRAN

So, do you have a plot of mobility for the driving point? ie velocity per unit force, vs frequency?

Cheers

Greg Locock

RE: Frequency response analysis using NASTRAN

(OP)
Let me be more clear. My intention is to find the equivalent static stiffness at '0'Hz. displacements are my outputs from the analysis. (SOL111). I am finidng the static stiffness only without constraining the frame

Regards
Sasank

RE: Frequency response analysis using NASTRAN

Oh, so is the plotted curve  horizontal at very low fgrequencies? If so then the stiffness is just the test load (1 N?) divided by that displacement.

  

Cheers

Greg Locock

RE: Frequency response analysis using NASTRAN

(OP)
Greg
Thanks for the reply. But, my question is can we validate this stiffness with some kind of test or theotically?

Regards
kamalakar

RE: Frequency response analysis using NASTRAN

Yes, by hitting it with an impact hammer and measuring the resulting vibration. The technique is called experimental modal analysis. Your noise and vibration laboratory will be able to do this for you.

Cheers

Greg Locock

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