MIL-DTL-82909A (OS)
made from 50 Hz to 500 Hz in approximately 7.5 minutes at the test levels indicated in figure 3. The
resonant points shall be noted and a transmissibility plot obtained. A resonant point is defined as a point
which has a transmissibility (output/input) of two or greater. If more than three points are noted from the
search, only the three most severe will be used for resonance dwell. The resonant points of separate battery
packs shall be considered the same if the modes are identical and the resonant frequencies fall within 3
percent of the mean resonant frequency for each mode. If the resonant points are the same (frequencies as
above and identical modes), the resonant frequency nearest the center of the 6 percent band shall be used
and the battery packs vibrated simultaneously during resonance dwell. If the resonant points are not the
same as defined above, the battery packs shall be vibrated separately during the dwell.
(2) Resonance dwell (5 Hz to 500 Hz): The three battery packs shall be vibrated along axis I at
70°F for 7.5 minutes at each resonant point. In the event that more than three points are noted, the three
most severe shall be used for resonance dwell. The response shall be peaked during the dwell period. The
test levels and schedule are shown in figure 3 and table VII, respectively. After the resonance dwell along
axis I, the battery packs shall be visually inspected for external damage.
(3) Sinusoidal cycling (50 Hz to 500 Hz): The three battery packs shall be subjected to the
sinusoidal vibration cycling along axis I at 70°F with the frequency varying logarithmically from 50 Hz to
500 Hz and back to 50 Hz in approximately 7.5 minutes. The test levels and schedule are shown in figure 3
and table VII, respectively. Depending on the number of resonant points found in the search, the battery
pack shall be vibrated for 30 minutes minus the time spent in dwell. After the vibration cycling along axis
I, the battery packs shall be visually inspected for damage. Results of the inspection shall be noted.
(4) Fixed dwell testing: After sinusoidal cycling, the battery packs shall be subjected to a series
of fixed dwells at 70°F along axis I as shown in table VII. The fixed narrow band dwell shall be performed
by sweeping the frequency about ± 5 percent of the specified center frequency. For example, the 100 Hz
dwell should be performed from 95 Hz to 105 Hz at the logarithmic sweep rate specified for the resonance
search.
(5) Sinusoidal cycling (500 Hz to 2,000 Hz): After the fixed dwell testing, the battery packs
shall be subjected to seven sinusoidal sweeps at 70°F along axis I. The frequency shall be varied
logarithmically from 500 Hz to 2,000 Hz and return to 500 Hz in approximately 7.5 minutes with an
applied input of ±10g. After testing along axis I, the battery packs shall be visually inspected and any
damage shall be noted.
(6) After completion on the gunfire vibration along axis I, the procedure shall be repeated along
the axis II orientation.
(7) After completion on the gunfire vibration along axis II, the procedure shall be repeated
along the axis III orientation.
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