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acceleration of vibration

acceleration of vibration

acceleration of vibration

(OP)
Hi,

I'm a stress engineer working in the transport aircraft industry.  Usually I deal with static strength analysis.  Though, we have had some projects lately dealing with avionics and avionics installations.

So, industry standard test documents (ie RTCA/D0-160D) require a 20g .011sec sawtooth-profile operational shock test as well as static crash safety criteria.  For our general analysis of black-box support structure, we want to relate this shock test to static inertia loads to find the controlling conditon for analysis, not testing.  I cannot seam to find any relation between the two searching the net and my old physics book.  All I find is harmonic related.

Sadly, I cannot locate my eng vibration text.

Any assistance would be very helpful.  Please consider this with a variable mass.

Thanks much,

tony

RE: acceleration of vibration

Here is an approach:

1.  Assume that the structure behaves as a single-degree-of-freedom system.
2.  Calculate or measure the natural frequency of the structure.
3.  Estimate the damping.
4.  Convert the shock pulse into a shock response spectrum, both in terms of acceleration and relative displacement responses.
5.  The peak responses of the structural are then taken from the shock response spectra, as a function of the natural frequency.
6.  Relate the peak acceleration and peak relative displacement values to some criteria limit, such as ultimate stress, fatigue, etc.

A good reference is:

D. Steinberg, Vibration Analysis for Electronic Equipment.
http://www.amazon.com/exec/obidos/ASIN/047137685X/vibra...

Tom Irvine
www.vibrationdata.com

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