MIL-STD 810 Temperature Shock Testing
MIL-810 temperature shock testing helps determine the ability of material to withstand sudden changes in temperature. “Sudden changes” are defined as “an air temperature change greater than 10°C within one minute.” The best temperature shock testing tests to prevent physical damage or deterioration in the material’s performance under temperature shock.
Keystone Compliance is a temperature shock lab with significant MIL-STD 810 temperature shock testing experience. Our temperature shock testing lab is perfect for all your temperature shock certification needs. Our test engineers understand the requirements outlined in MIL-810G temperature shock and MIL-810H temperature shock testing.
The following information is extremely technical in nature. It provides a summary of Method 503.7, as derived from the MIL-STD 810H temperature shock section. It also applies previous versions of the standard including MIL-STD 810G temperature shock.
What are the Effects of a Thermal Shock Environment?
The effects of thermal shocks are usually more severe near the outer portions of the material. Generally, the further from the surface, the slower and less significant the thermal changes. Transit cases, packaging, etc., will lessen the effects of thermal shock on the enclosed material even more.
Sudden temperature changes may either temporarily or permanently affect the operation of materiel. Consider the following typical problems to help determine if this method is appropriate for the material being tested. This list is not intended as all-inclusive.
- Shattering of glass vials and optical material.
- Binding or slackening of moving parts.
- Cracking of solid pellets or grains in explosives.
- Differential contraction or expansion rates or induced strain rates of dissimilar materials.
- Deformation or fracture of components.
- Cracking of surface coatings
- Leaking of sealed compartments
- Failure of insulation protection.
- Separation of constituents
- Failure of chemical agent protection.
- Changes in electrical and electronic components.
- Electronic or mechanical failures due to rapid water or frost formation.
What are the Appropriate Test Levels and Conditions for MIL-STD 810 Thermal Shock Testing?
Select this method based on the MIL-810H thermal shock test item’s requirements documents. Then tailor the process by identifying appropriate parameter levels, test conditions, and techniques for the procedure. Base testing on requirements documents, the Life Cycle Environmental Profile (LCEP), and information from MIL-STD-810 thermal shock. All testing should take place in a thermal shock lab; this method addresses several exposure situations.
These situations are aircraft flight exposure, air delivery – desert, and ground transfer – ambient to either cold regions or desert. Based on the expected deployment, determine which test variation is applicable. Exposure temperatures should reflect shocks from controlled ambient temperature conditions to high or low temperatures. Base the exposure range on the expected service conditions, but extend the temperature levels as necessary to detect design flaws.
Stabilize the whole test item temperature or, if known, the point of interest prior to transfer. If the LCEP indicates a duration less than that required to achieve stabilization, the duration from the LCEP should be used. The critical point of interest may be near the surface of the item. In such cases, a considerably shorter duration may apply rather than complete stabilization of the item.
When selecting test levels consider different environments. For aircraft flight exposure material may be exposed to desert or tropical ground heat or possible direct solar heating. Then it may be immediately afterwards, exposed to the extreme low temperatures associated with high altitude. If not expended, items may be exposed to thermal shock(s) when the platform aircraft returns to a hot ambient environment.
For air delivery-desert exposure this is appropriate if the material is delivered over desert terrain from unheated, high altitude aircraft. For ground transfer ambient temperatures may be akin to cold regions or desert. This is intended to test the effects of movement to and from ambient conditions and cold regions or desert environments. Use engineering design to detect issues related to marginal design.
What Exposure Conditions Should be Tested for in a Temperature Shock Laboratory?
Choose the test temperatures either from field data or from the MIL-810 thermal shock requirements documents. If this data is not available, use the expected deployment application, or world areas that the material deploys from. Or use the most extreme non-operating temperature requirements. It is best to use a range of temperatures reflective of those anticipated in service, rather than an arbitrary extreme range.
Exposure conditions will vary. For aircraft flight exposure, thermal stresses and rates that material experience depend on ambient conditions and flight conditions. Performance of the onboard environmental control systems is also a factor.
For air delivery, exposure depends on the conditions in the aircraft compartment, and the ground at the point of impact. Use a lower temperature extreme assuming an unheated, unpressurized aircraft cargo compartment with the aircraft at an altitude of 8 km. This is the limiting altitude for cargo aircraft because of oxygen pressure requirements when the compartment is unpressurized immediately before airdrop.
For ground transfer exposure, thermal shock could occur during movement to and from environmentally conditioned enclosures to exterior ambient temperatures. The conditions for cold regions enclosures are indoor air at 18-24 °C, with an RH of 30 to 50%. These conditions roughly correspond to normal heating practices in cold regions. Determine if solar heating of material occurs prior to transfer from a desert environment to an air-conditioned enclosure.
What Should the Duration of the Test Be for the Best Thermal Shock Testing?
Procedure IA is for material that is likely exposed only rarely to thermal shock in one direction. For this procedure, perform at least one shock for each appropriate condition, i.e., low to high temperature, or vice-versa. This should be a one-way shock, from constant extreme temperatures.
Procedure IB is single cycle shock from constant extreme temperature. This is for material likely exposed to only one thermal shock cycle. Perform one shock for each appropriate condition, i.e., low-to-high temperature, and one in the opposite direction.
Procedure IC consists of multi-cycle shocks from constant extreme temperature. There is little available data to substantiate a specific number of shocks when more frequent exposure is expected. In lieu of better information, apply a minimum of three shocks at each condition. This means three transfers from cold to hot, three transfers from hot to cold, and a stabilization period after each transfer.
The number of shocks depends primarily on the anticipated service events. The objective of this test is to determine the effect of rapid temperature changes on the material. Therefore, material should be exposed to temperature extremes for as long as those of actual operation, that required for temperature stabilization.
Procedure ID consists of shocks to or from controlled ambient temperature. This procedure follows the durations of Procedures IA to IC, except all shocks are to and/or from controlled ambient conditions.
What Thermal Shock Testing Lab is Best?
Keystone Compliance has been recognized as one of the best temperature shock labs in the country. Our experts are able to provide thermal shock certifications for commercial, military, and aerospace products. Contact us to learn why so many manufacturers rely on Keystone Compliance to meet their compliance testing needs.
There have been several versions of temperature shock testing procedures in MIL-STD-810 temperature shock testing. Below is a list of each version and the appropriate method number:
- MIL-STD-810A Test Method 503.1 Temperature Shock Testing
- MIL-STD-810B Test Method 503 Temperature Shock Testing
- MIL-STD-810C Test Method 503.1 Temperature Shock Testing
- MIL-STD-810D Test Method 503.2 Temperature Shock Testing
- MIL-STD-810E Test Method 503.3 Temperature Shock Testing
- MIL-STD-810F Test Method 503.4 Temperature Shock Testing
- MIL-STD-810G Test Method 503.5 Temperature Shock Testing
- MIL-STD-810H Test Method 503.7 Temperature Shock Testing