Downloaded from https://www.everyspec.com MIL-STD-81OC 10 March 1975 MSTHOD 513.2 ACCELERATION 1. PURPOSE. The acceleration test is performed to determine if equip- ment is constructed to withstand expected steady state stresses and to insure that performance degradationsor malfunctions wi11 not be produced by the simulated service acceleration environment. Procedure I is the structural test and procedure II is the operational test. 2. APPARATUS. Either of two facilities may be utilized for accelera- tion tests:’ a centrifuge,or a track and rocket sled facility.
A centri- fuge of adequate size is recommended for all structural and most operation- al tests because of the convenience and ease’of control. However, the . performance of space oriented equipment, such as gyros, space control platforms, etc, are difficult to test on a centrifuge, even when a counter- rotating fixture is employed. A rocket s1ed run is advantageouswhere strictly linear acceleration is required. 3. PROCEDURES. The test item shall be subjected to both tbe structural and the operational test, unless otherwise specified. 3.1 Mounting of test item.
Direction of forward acceleration is always considered to be the direction of the vehicle accelerationand equipment shall be oriented accordingly,using its normal moturtingmeans. For centrifuges, the location of the test item (with reference to the G level established for the test) shall normally be determined by a measurement from the rotational center of the centrifuge to the geometric center of the test item.
Should any point of the test item nearest the center of the centrifuge experience less than 90 percent of the specified G level, the test item shall be moved outward on a radius of the centrifuge or the speed of rotation shall be increased until not less than 90 percent of the specified G level is obtained. Caution: If the furthest end of the test item experiences more than 110 percent of the desired G level at the geometric center (while the nearest end experiences 90 percent or under), then the test item may be tested using a lower speed and a larger radius centrifuge arm.
For large test specimens exceptions should be made to allow for maximum gradient b%ed on the existing availabilityof large centrifuges in commercial or Government test facilities. 513.2-1 METHOD 513.2 10 March 1975