Vibration Engineering

Nohman

I've got something of an odd problem I need help from a more experienced engineer than myself to solve, and frankly am running out of places to ask.

Esseentially, I'm looking at various hard drives, but the amount of vibration they produce is an important factor whether they are suitable or not. Problem is I've found that various specs use different measurements, and I'm not quite sure how to convert from one to the other. The requirements are specified in mm and frequency, whereas I've seen values listed in g2/Hz, 10-55Hz (1 minute sweep) or m/s2.

What I'm after I guess is a way of converting between the various units, so that we can actually compare one against the other.

Donovan Puppyfucker

You could save yourself a bit of work by procuring an SSD drive.

Dunadan019

http://www.mobiusinstitute.com/Calculator.aspx?id=2509

that should help.

Nohman

chrishallett83 wrote: »

You could save yourself a bit of work by procuring an SSD drive.

I would love to, although the cost of SDDs in the size and amounts needed puts it somewhat out of our price range unfortunately.

Dunadan019 wrote: »

http://www.mobiusinstitute.com/Calculator.aspx?id=2509

that should help.

Hmm, it does somewhat, although unfortunately specifying frequency and displacement doesn't seem to work, only the other values do with known frequencies.

Dunadan019

Nohman wrote: »

chrishallett83 wrote: »

You could save yourself a bit of work by procuring an SSD drive.

I would love to, although the cost of SDDs in the size and amounts needed puts it somewhat out of our price range unfortunately.

Dunadan019 wrote: »

http://www.mobiusinstitute.com/Calculator.aspx?id=2509

that should help.

Hmm, it does somewhat, although unfortunately specifying frequency and displacement doesn't seem to work, only the other values do with known frequencies.

works for me.

there are 1000 microns in a mm.

Balgair

I'm not sure if this is completely off-topic, but it's very easy to reduce the effects of hard drive vibration by simply suspending your drives in their enclosure, like so:

.
I'd recommend using stretch magic:

, but you can also use pretty much any elastic band, bungie cords, etc. This method tends to reduce a tremendous amount of noise/rattle associated with vibration-- Again, I don't know what your end-goal is, but just thought I'd chime in.

msuitepyon

Looking at this quick reference sheet, it gives an equation relating spectral density (the g^2/Hz number) as a function of peak-to-peak displacement (D, in meters) and f (frequency, in Hz).

Rearranging the equation and using the known frequency from your requirements, you can solve for D and compare it to your amplitude requirement.

EDIT: It also appears that your spectral frequency is only limited to the specified frequency range (10-55 Hz).