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Identify
the exposure temperature for a given load, and the characteristic
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time
associated with that load
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Cooling: usually use the end temperature, and the
time to equilibrate
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Ignition
transient: use the exposure
temperature and the ignition rise
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time
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Shock: exposure temperature and the time to
peak pulse amplitude
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Calculate
the log reduced time, and look up properties
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Example: Cool to –30F in 48 hours
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Log(t) =
log(48 hours * 60 min/hr) = +3.459
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Log(aT)
= -[-416.42+(5.82)(-30)]/[197.3+(-30)] = +3.533
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Log t/aT
= +3.459 – 3.533 = -0.074 minutes
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