;:._ . .,5 Downloaded from https://www.everyspec.com MILATD-81@ 15 June 1967 /- ) METHOD 513.1 ACCEI.FJUTION L =. - lhe accelerationtest is perfomed to determine if equipnent is conetruoted to withstand expecteds!teadystate atressca and to insure that performance degradationsor malfuuctlonewill not be prnduced by the eimulated Barvice acoelerationenvironmentother than gravity. Procadure I is the struc- tural test and Procedure II is the operational test. 2. Apparatus. - Eithar of tw facilities may be utilised for acceleration tests: a centrifuge,or a track and rocket sled facility.
A centrifuge of ade- quate size Is reccmmandedfor all structural smd most operationaltests because of the convaniermeand ease of control. However, the performanceof space oriented equlpnent,such as gyI’os,epace control platfonnc, etc., are difficult to test on a centrifuge,even when a counter-rotatingfixture is amployed. A rocket sled run is advantageousshare &trlctQ linear accelerationis required. 3. fiooeduree.- lhe tesk itsm ehall be subjected to both the structural and ,.- the operational teat, unless otherwise specifiad. 3.1 Mountl.n$! of test item.
- Direotion of forward accelerationie always con- sidered to be the direction of tha vehicle accelerationand equipment shall be oriented accordingly,wdmg its nermal mourrtl.mg means. For cemtrifuge8,the location of the test itcsn(withreference to the G level established for the test) shall normally be detenninadby a measurement from the rotatinhal centar of the cen- tri~e to the gemetric center of the test item.
Should w petit of the test itm nearest the center of tha cemtrii’ugeexperienceless than 90 percent Of the specified G level, the test itan shall be moved outward on a radius of the cen- trifuge or the speed of rotation shall be increased vntil not less than 90 percent of the specified G lavel ia obtained. Caution: If the furthest end Of the test item .xperiancesmore than 110 parcent of the desired G lavel at the geometric center (while the nearest and expariances90 percent or umdar), then the test . itan may be tested using a lower speed and a larger radius centrifuge am.
For large teat speclmame axceptiona should be made to allnw for maximum gradient baaad on the axisting availabilityof large oentrifugee in canmercial or Govarrnrmntt=t facilities. (-- 3.1.1 Teat itan orientation (centrifu ~ e . - When a centrifuge is used to attain the required accelerationlevele, the test itaceshall be oriented as follows: Fore: Front or forward end of tact itssnshell face toward center of cemtrifhge. Aft: Reveree item 180 d0gree8 from tha poaitien. up: Top of specimen shall face toward center of centrifuge. Down: Reverse item 180 degraes frrxothe %Pn ~sltien. Lateral: Each side (right, left) in turn shell fece toward canter of centrifuge. ,.. 513.1-1 ”.’ .
METHOD 513.1 ...... Xl Oct~ber 1969 .,. .