MIL

Here is what Military Standard 810 Revision "F" has to say on this subject:

"4.2.1.1 Acceleration input control strategy.
Input control is the traditional approach to vibration testing. Control accelerometers are mounted on the fixture at
the test item mounting points. Exciter motion is controlled with feedback from the control accelerometer(s) to
provide defined vibration levels at the fixture/test item interface. Where appropriate, the control signal can be the
average of the signals from more than one test item/fixture accelerometer. This represents the platform input to the
materiel and assumes that the materiel does not influence platform vibration."

Efforts began in 2005 to update "F" to "G". In early May 2006 Steve Brenner (ERI's fixture design instructor - scheduled for Las Vegas, Nevada November 14-16) and I attended a "G" committee meeting at Phoenix, Arizona (during the IEST annual meeting). We'll attend again (during the SAVIAC meeting) at Monterey, California October 29-November 3. Meantime, here is what we have suggested for 4.2.1.1:

"Input control is the traditional approach to vibration testing. An accelerometer will be mounted on the fixture within 1 inch of each DUT mounting point. Exciter motion is controlled with feedback from any of these. Perform a 1g sine sweep. If all agree within 10%, the fixture is acceptable. If not, the fixture is not acceptable. Neither averaging of the several accelerometers (some inputs would exceed the required acceleration) nor extremal control (all other inputs would be less than the required acceleration) is acceptable".

If Anonymous will communicate with me by a private e-mail, I'll send a few other "G" proposal paragraphs that Steve and I submitted.

Best wishes,

Wayne