IF-.., Downloaded from https://www.everyspec.com ,MIL-STD-81OD 19 ‘July 1983 b. Procedure VI should not be used if it.can be demon- strated ,that the shocks from the transit drop test are of a higher level,. It is considered appropriate”for mediub-to-large test iteme that have a maximum. dimension greater than approximately 23 cm (nine inches). (Small items will be .0 tested to higher level? during transit drop.) c.. ~t conditiw. The test item in this test shall.be raised.at~,orie“~ edge four inches above a solid wo-adenbench top or unti1 the chassis forms an angle of 450 with the bench top or until”point of balance is reached, whichever is less.
(The bench top must be at least U.25 cm [1.6’15inches] thick.) A series.of drops.ehall be performed in.accordance.with 11-3.6. . ,- d. &&&&a. The heights used during this teSt were a>t by exa.mining the typical drops that are commonly made by bench technicians and assembly line personnel: ,, I-3.9”’Procedure W - pvrote~ > a. Procedure VII is intended for equipment to be subjected to shock from explosive devices. The shock can be characterized as.an ~scillatorY transient, with significant frequency content from 100 to 10,000, Hz, which decays to a few percent of its maximum acceleration in 5 to 15 milliseconds (reference b). The shock response spectrum often exceeds several.
thousand at frequencies above,1,00Q Hz (for Q.= 10)... This procedure al.sO~~ aPplieS to .VituatiOnswhich may yield shocks of comparable eeverity, suc,bas atmospheric reentry or water entry of missiles and high-velocity aerodynamic buffeting of high-performance weapon systems. b. This test procedure will not be required along any axis for which both the following are satisfied:
(1) the test spectrum from a ~~ random vibration test (see 1-3.3b) or a functional shock test exceed thie spectrum requirement and (2) if the test spectrum requirement above the frequency range specified for the random vibration or functional‘“shocktest does not exceed g values of O.8 f, where f is the’frequencY”in Hz. (The 0.8 f: acceleration limit corresponds to approximate y 50 in/see spectral velocity. A basic for uee of velocity as a criterion of severity is given in reference c. The value of 50 in./see is selected because of limited observations (unpublished) that military-quality equipment does not tend to exhibit shock failures below a responee spectrum velocity of 100 in./see.) c.
Field measured data, or data obtained from a eimilar environment ueing appropriate dynamic scaling (reference.b, vol. VI) , will be used to define the shock’test reeponse.spectrum requ$.rernent alOng each.@f three orthogonal axes. Measured data will .beconverted intO.tes! requirements in ~, -, accordance with the guidelines outlined fOr the functional test cOnditiOns, I-3.3, with two exceptions: (1) Measured or empirically scaled data will alwaYs be required tO.
determine the teat response spectrum, .2 .....’..,, .,, , The allowed duration for the test shock time history used for response spectrum analysis can be 20 milliseconds or less, unless a longer duration can be justified by applicable data. (2) I o I.UZTHOD516.3. 19 JUIY 1983 516.3-14.