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Vibration profile calculation for shaker table

by yrealyea
Tags: calculation, profile, shaker, table, vibration
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yrealyea
#1
Feb4-13, 12:44 PM
P: 3
Hi guys,

I hope we got some expert out here for vibration profile problems.

I have a device that need to be on a shaker table but I need to "find" its profile to see if the shaker table can actually run this experiment. The Shaker table is Unholtz-Dickie system SA30-560B and I have data of this table's profile in Acceleration (g PK) vs Frequency (Hz).

My device with fixture weights 23.5lbs, and I need to run it between frequency of 10 to 500 Hz with 30.59g force, this is a long life test. Can someone help me on finding the X, X2, X3?

Also that ASD stands for what? I can't figure out what that stands for, but the table's profile has in Acceleration of g-force Peak vs Frequency instead of ASD vs. Frequency.
Attached Thumbnails
unholtz-dickie shaker profile.png  
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AlephZero
#2
Feb4-13, 04:16 PM
Engineering
Sci Advisor
HW Helper
Thanks
P: 6,929
ASD = acceleration spectral density (similar to power spectral density).

The values of x, x2, x3 are all defined by the graph and the table of values underneath. If you don't understand how to interpret the data, I think you need to review the basics of random vibrration theory and testing.

There is no way you will get 30g at 500Hz from that ASD specification.

You also need to check the force output is big enough to shake the mass (plus the mass of the table, etc) at 30g.

This http://www.acutronic.com/uploads/med...tEquipment.pdf suggests the continuous power rating of the SA30 amp isn't big enough.
yrealyea
#3
Feb5-13, 06:48 AM
P: 3
Quote Quote by AlephZero View Post
ASD = acceleration spectral density (similar to power spectral density).

The values of x, x2, x3 are all defined by the graph and the table of values underneath. If you don't understand how to interpret the data, I think you need to review the basics of random vibrration theory and testing.

There is no way you will get 30g at 500Hz from that ASD specification.

You also need to check the force output is big enough to shake the mass (plus the mass of the table, etc) at 30g.

This http://www.acutronic.com/uploads/med...tEquipment.pdf suggests the continuous power rating of the SA30 amp isn't big enough.
Alpha, I drew that chart with table there for convenient, I'm actually looking to calculate the three forces in 3 different axes on my device, so they are not the x, x2, and x3. I know that shaker table can't sustain the test somewhere below a hundred Hz. But I need to find out what is the exact range that it can't be tested so that I can skip that part of test and run the rest of profile that shaker can take.

Again don't worry about the fixture weight for now, can you tell me how you can calculate the PSD x, x2 and x3? I need those 3 values to compare it to the shaker table's profile and see at which point they overlap.

Thanks.

yrealyea
#4
Feb6-13, 07:34 AM
P: 3
Vibration profile calculation for shaker table

Bump, anyone able to help me?
yrael
#5
Mar4-13, 10:19 AM
P: 7
I found the answer, in case anyone else like to know how to solve it.

I was giving an ASD value which represented value in mid (flat) line of profile, I used db/Oct and Hz, along with ASD flat line value with this equation:

P1=P2*(f1/f2)^((db/oct)/3)

P1 is value of ASD I'm looking for at f1=10 Hz
While P2 is the given ASD value of flat line of profile.

Also, if the value of db/Oct is negative then you will use this:

P1=P2/((f1/f2)^((db/oct)/3))


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