Using The
Pseudo Velocity Shock Spectrum For Shock Damage Potential Part 2
Dr. Howard Gaberson, MFPT Society/SAVIAC
Abstract:
To defend PVSS on 4CP I show computations to illustrate pseudo velocity
compared to relative velocity shock spectra indicating pitfalls for relative
velocity. The difficult relative velocity low frequency
problem and lack of asymptotes. Next I go into details of
experimental failure tests to determine which transient motion analysis method
is the best indicator of damage potential. Evaluation of shocks of
failing blowers exposed to six different violent loadings. Failure data
time histories are analyzed into peak g levels, time histories, Fourier
transform magnitudes on 4CP, PVSS on 4CP, and acceleration shock spectra.
The best damage potential analysis is the damped PVSS on 4CP, but damping is
essential. Next we consider shaker generated shocks and
analyze examples of synthesized shocks to meet an acceleration SRS, and
pre and post pulse simple shocks that can be shaker generated. They lack
low frequency content. The rebound on a drop table simple shock reduces
low frequency content. Next we analyze shock isolation and consider
the equipment lowest mode natural frequency and the equipment fragility.
Most shock isolation literature is wrong because it is based on peak
acceleration. Theoretical and experimental shock
isolation. Explosive PVSS, Pyro shock
PVSS. We show how to apply PVSS on lumped MDOF systems and continuous
systems (beams, roods , plates). We consider use
of damping. Heavy damping is needed to show polarity or positive and
negative spectra. Damping precludes swept sines
spectrum generation; it makes a kind of broccoli spectrum. Deceptive SS calculation at sparse selected frequencies.
Finally some calculation issues: mean removal and detrending.
Illustrate with the
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