Mil-Std-810 Random Vibration Profile Question

[stockdam]

Hi,

Can anyone help to explain a profile in Mil-STd-810.

The profile is shown in Fig 514.5C-9.

It's a vibration profile for propellor aircraft.

L0 is the g2/hz value for the first prop frequency. The profile rolls off at 6db/octave. How do I work out the g2/hz for the other frequencies (harmonics)?

f1 is twice f0 so that's an octave. Does this mean the g2/hz at f1 is L0/2 or is it L0/4 - is the g2/hz rolling off at 6db/octave or is the g rolling off at this rate and therefore g2/hz is a factor of 4 per octave lower?

 

[KENAT]

If you don't get an answer here try forum384

 

[IRstuff]

MIL-STD-810 basically says that you need to get measured data. Table 541.5C-II is the only guidance you can get

TTFN

Eng-Tips Policies FAQ731-376

 

[pstuckey]

g^2/Hz is LO/4 at an octave.

To see an example with numeric values look at figure 514.5C-17.

Peter

 

[stockdam]

Thanks Peter...that's exactly the answer I was looking for and confirms my understanding.