NTS Solar Radiation (Sunshine) Facility MIL-STD-810G

Solar radiation can be very damaging to materials and equipment stored and used outdoors. MIL-STD810, Method 505 is designed to evaluate materials as they are exposed to the radiation and heating effects of direct exposure to sunlight. NTS has developed and is now operating state of the art facilities in Tempe, Arizona for this testing. Proprietary radiation sources provide the spectral content and irradiance to the exacting tolerances required by the

standard. In addition to the radiation requirements, the stan-dard also requires that temperature and wind speed also be controlled to tight tolerances. NTS test cells are purpose built to provide the correct environ-ment to replicate the conditions seen in the field as required by the MIL Standard. NTS radiation sources are engineered to provide the correct spectral content, which includes UV A, UV B, visible, and infrared wavelengths.

NTS operates several test cells dedicated to solar radiation testing with internal volumes of 1000 cubic feet, which allow economical testing of larger test articles. Multiple radiation sources are available to provide the required heat and ra-diation in a configuration that allows the test subjects to be irradiated from any angle. Uniformity of the radiation across the test article is controlled within specification limits.

NTS engineers have designed a user interface system based on LABVIEW software that provides full control of all required pa-rameters for testing. This proprietary software monitors spectral content, irradiance, airspeed, test article and chamber tem-perature and other selectable parameters and displays the data in real-time. All parameters are plotted to graphical for-mat for review and inclusion in the test report. The system auto-mates the setup and calibration, resulting in better accuracy and lower cost to the customer. All instrumentation is cali-brated by an accredited laboratory, and is traceable to NIST. Full equipment lists with calibration traceability are provided with the subsequent test report.

Examples of test materials • Glazing and transparent armor • Carbon fiber , Kevlar, and other armor • Plastics and elastomers • Electrical and electronic components • Portable communication equipment • UAV and control equipment • Alternative power equipment • Any materiel used in an outdoor application

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MIL-810-G SOLAR TEST PROCEDURE 1

Solar Intensity (W/m2) Chamber Temperature UUT Temperature top under cover

UUT Temperature bottom Plate Temperature under UUT Plate Temperature

NTS Solar Radiation (Sunshine) Facility MIL-STD-810G

Advantages of NTS system • Spectral content and irradiance meet MIL-STD-

requirements • Better control of all test parameters • Ability to handle larger test articles • Ability to orient test article/radiation source as required • Real-time monitoring and recording of irradiance and

spectral content

Procedure 1 testing (Heating Effects) • Used to investigate response temperatures when materiel

is exposed in realistically hot climates, and is expected to perform without degradation during and after exposure

• Used to generate maximum response temperature of the test item, for use in Procedure 2 solar testing

• It is preferable to use the solar radiation test rather than a temperature-only test because the effects of differential heating caused by solar radiation on materiel are un-known

Procedure 2 testing (Actinic Effects) • Used to investigate the effects on materiel of long expo-

sure to sunshine • An accelerated designed to reduce the time to repro-

duce the cumulative effects of long periods of exposure • Chambers designed to provide enough cooling air to pre-

vent the test item from exceeding peak temperatures that would be attained under natural conditions

Current capabilities • Procedure 1 system - 4’ x 6’ irradiated area • Procedure 2 system - air cooled Mecury-doped Metal Hal-

ide lamps - 4’ x 6’ irradiated area • Procedure 2 system - water cooled capillary lamps - 4’ x 6’

irradiated area