Temperature Shock

MIL-STD-810G METHOD 503.5

A temperature shock test is designed to determine if the equipment can withstand sudden changes in ambient temperature without experiencing physical damage or deterioration in performance. So "sudden changes" is defined as "a change in air temperature of more than 10 degrees Celsius in one minute."

This method is designed to evaluate the effects of sudden temperature changes of the exterior surfaces of equipment, complex items on the exterior surfaces, or interior items located near exterior surfaces.

This method is essentially a surface test, usually of:

A. Transfer of materials between climate-controlled environmental zones and extreme external environmental conditions or vice versa.

B. Elevation from a high ground temperature to a high altitude using a high-performance vehicle (hot to cold only).

C. Air passage / air pressure drops at high altitude / low temperature from aircraft. In this case only the outer layer is inspected (packaging or surface).

The effects of thermal shocks are usually more severe near the outer parts of the equipment. The greater the distance from such an area (depending, of course, on the properties of the material involved), the less significant the impact and the thermal changes. In enveloped systems and the like, enveloping will further reduce the effects of thermal shock on closed equipment. Sudden changes in temperature may temporarily or permanently affect the operation of equipment. The following are examples of problems that may result from exposure to thermal shock that may be related to the test subject. These typical problems should be considered to determine if this method is appropriate for the test subject.

 

A partial list includes:

A. Structural

1. Glass explosion in optical equipment.

2. Distortion and / or destruction of moving parts.

3. Explosion of bullets or sealed elements (explosives).

4. Differential contraction or expansion rates

5. Distortion or breakage of components.

6. Explosion of surface coatings.

7. Cell leakage.

8. Insulation puncture.