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Random Response Analysis (dB/octave to ((m/s^2)^2)/Hz)

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Hi there,


 


As of my knowledge for doing a random response analysis we require a ASD Vs frequency curve.


 


But here I have the "ASD slope" values (units= dB/Octave) and frequency range.


 


Can any one please tell me how to get "ASD" values from "ASD slope" values.


 


Is there any direct formula to convert them.?


 


I have referred the following site for that but I didn't understand.


http://femci.gsfc.na...mequations.html


 


And also Can any one tell me what is the Verification process for random vibration analysis theoretically. If not with a sample problem,,..


 


Thanks in advance


 


 


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Hi,


 


First : conversion from dB/oct to g²/Hz :


 


for example, you've got a table as folowing:


From 20 to 200 Hz, level = 0.3 g²/Hz


From 200 to 300 Hz, level = -10 db/Octave


From 300 to 1000 Hz, level =0.078 g²/Hz


 


You have to calculate the folowing parameter : alpha=(-10 dB/Octacve)/(10*LOG10(2)) ; K=(0.3g²/Hz)/(200Hz^Alpha)


For F<200, level = 0.3 g²/Hz


For 200<F<300, level =K*F^Alpha


 


Second : Random Tutorial:


 


Use Altair Tutorial RD-2010 and RD-2050


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