How to convert g^2/HZ to g ?
How to convert g^2/HZ to g ?
(OP)
How to convert g^2/HZ to g? I have PSD measurements of an operating Hard disk drive. The unit is g^2/HZ. I want to convert this unit to g so I can use equation F=ma to calculate the force that HDD is exerting on the mounting bracket at different frequencies; so then I can use these numbers in promechanica in the load function to capture the vibrational force that the HDD is exerting on the bracket. I would highly appreciate any help.





RE: How to convert g^2/HZ to g ?
RE: How to convert g^2/HZ to g ?
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RE: How to convert g^2/HZ to g ?
so the area under the PSD is in terms of g^2 ??
RE: How to convert g^2/HZ to g ?
If you are only interested in a specific frequency, then you need to use Miles' Equation: Grms = sqrt( pi/2 * f * Q * ASD ). ASD is the PSD value at the specific frequency, and Q is typically (but not always) 10, it's based on the damping ratio if you know that. If you need Gpk, multiply by 3.
Hope this helps.
Jim
Jim Kinney
Kennedy Space Center, FL
RE: How to convert g^2/HZ to g ?
You misunderstand. The PSD is the environmental random vibration. The response to that is, as Jim says, the Mikles equation.
Your hard drive bracket has only a few resonance points of interest . In that case you apply the Miles equation to get the separate responses.
Also, to add to ,Jim's discussion, the Q value is 1/2*sigma where sigma is the critical damping ratio of the single degree of system and 3 factor is the standard 3 sigma probsbility value, but not the peak.
RE: How to convert g^2/HZ to g ?
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Doug