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Low temperatures have adverse
effects on almost all basic materiel. As a result, exposure of test items to low
temperatures may either temporarily or permanently impair the operation of the
test item by changing the physical properties of the material composing it.
Therefore, low temperature test must be considered whenever the test item will
be exposed to temperatures below standard ambient. Examples of some problems
that could occur as the result of exposure to cold are:
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Hardening
and embrittlement of materials.
-
Binding
of parts from differential contraction of dissimilar materials and the
different rates of expansion of different parts in response to temperature
transients.
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Changes
in electronic components (resistors, capacitors, etc.).
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Stiffening
of shock mounts.
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Cracking
and crazing, embrittlement, change in impact strength, and reduced strength.
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Static
fatigue of restrained glass.
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Condensation
and freezing of water.
The Ranger is tested to the Severe Cold standard of one 24-hour cycle at
-40 C (-40° F).
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