Downloaded from https://www.everyspec.com MIL-STD-810D 19 July 1983 (2) number of show. The equipment undergoing test shall he subjected to a sufficient number of suitable shocks to meet the specified test conditions at least three times in both directions along each of three orthogonal axes. A suitable test shock for each’direction of each axis ia one that yields a response spectrum that equals or exceeds the required test spectrum over the specified frequency range when using a duration of twice the specified TE value for the test shock time history, and when the effective duration of the shock ia within twenty percent of the specified TE value.
The spectra are to be determined for positive and negative maximum accelerations (either maximum’absolute or equivalent static), Q . 10, and at lea”stl/6-octave frequency intervals. If the required teat spectrum can be satisfied simulta- . neously in both direction. along an axis, three shock repetitions will satisfy the requirement for that axis. If the requirement can only be satisfied in one direction, it is permissible to change the test setup and impose three additional shocks to satiefy the spectrum requirement in the other direction; setup change possibilities are to reverse the polarity of,the test shock time J history or to reverse the test item orientation.
@ It is permissible to simultaneously meet the test requirements along more than one axis with a single test shock. Consequently, it ia conceivable that a minimum of three test shock repetitions will satisfy the requirements for both directions of all three orthogonal axes. At the other extreme, a total of eighteen shocks will b,erequired if each shock only satisfies th”etest requirements in one direction of one axis. (3) ~ test item. The test item shall be operational before, during, and after test as is appropriate to ita functional use. d. ~.
The intent of this test ia to disclose failures which may result from, or adjustments necessitated by, shocks experienced hy an item during use in the field. Even though an item has successfully withstood even more severe shocks during shipping or transit chock tests, there are differences in support and attachment methods and in functional checking requirements that make this additional test necessary. Tailoring of the test is required when data are on hand, can be measured, or can be estimated from related data using accepted scaling techniques.
When such data cannot be gotten, pulse waveform control, as defined in figure 516.3-4, may be ueed, although testing in both directions is required to assure meeting the spectrum requirements of figure 516.3-1 in the negative direction. I-3.4 a. > Procedure II is to be used when equipment will require a shipping container. It establishes a minimum critical acceleration level for a handling drop height. This acceleration level may later be furnished to a package designer as an acceptable critical acceleration. b. ~. Procedure II is not intended for testing extremely fragile equipment such as missile guidance systems, precision-alined test equipment, gyros, inertial guidance platform9, etc.
When the critical acceleration is required, procedure III (I-3.5) will be used. METHOD 516.3 19 July 1983 516.3-5