Downloaded from https://www.everyspec.com ~ MIL-STD-81OD 19 July 198.3 h. Fading of colors of color-coded components. I i. Changes in characteristics of elastomers and polymers. .i. Blistering and peeling of paints and other finishes. I k. Softening of potting compounds. 1-2.2 ~. In addition to the heating effects of I-2.1, which are caused by the infrared portion of the solar spectrum, certain degradation from solar energy may be attributable to other portions of the spectrum, particularly the ultraviolet.
Since the rate at which these reactions will occur generally increases as the temperature rises, the full spectrum must be used to adequately simulate the actinic effects of solar radiation. Some examples of deterioration caused by actinic effects are: a. Fading of fabric color. ~.> b. Checking and fading of paints. Deterioration of natural and svnthetic elastomers and oolvmers through photochemical reactions initiated by sh&ter wavelength radiation.” c. I-3 S AND NOTE: This test method should be aoolied at the end of the tailoring process described in section 4 of this standard. a. ~.
This method is used when the test item is likely to be exposed to solar radiation in the open in hot climates during its life oycle, and the effects mentioned in I-2.1 and I-2.2 are of concern. In most cases, this method should replace method 501.2 (high temperature). b. &WdJQC& This method is not to be used to simulate the heating effects that result from enclosed or covered storage conditions. The solar spectrum and energy levels are those that are received at sea level. ‘The ultraviolet portion is simulated only in a general way, but is considered adequately representative of levels in most geographic areas. c. ~.
(See General Requirements, U.Q.U.) The solar radiation test may be applied at any stage in the teat.Program. i d. lest variat-jans. This method is composed of two solar radiation tests: procedures I (cyclic) and II (stsady state). . (1) The choice of test procedure is based on the following: (a) The anticipated exposure circumstances. ,J (b) The expected problem areas within the test item. (c) The duration ‘ofexposure to solar radiation. (2) The related test conditions that are used during the test are determined by: METHOD 505:2 19 JUIY 1983 505.2-2 ..-.