Except for helicopters, the test levels for the six test directions are alwsiys based on the forward acceleration of the vehicle. In the case of helicopters, lOrward acceleration is unrirelated to aeeeleration in the other directions. Tables 513.4-1 and 513.4-II list test levels for Procedure I (Structural Test) and Procedvire II (Operational Test), respectively. Factors which influence the test levels are:

a. Forward acceleration of the vehicle, knowi or unknown?

b. Orientation of test item in the vehicle, imown or игаспот?

e= For fighter and attack aircraft, acceleration loads induced roll, pitch, and yaw change maneuvers.

These factors are accounted for as follows.

1-3.3 Forward aeeelerationJcnowTi and test itea orientation known. №an the forwiard acceleration of the vehicle is known and the orientation of the test item is knowi, the acceleration test levels for Procedure I tests are those valws that are obtained from table 513.4-1 when the known forward acceleration is substituted for A in the table. The acceleration test levels for Procedure II tests are obtained in the same manner using table 513.4-II. For helicopters, the test levels in the tables apply regardless cf forward acceleration.

1-3.4 Forward acceleration known and test item orientation tnkncwn. Ммп the forward acceleration of the vehicle is known and the orientation of tbe test item is unknown, the acceleration test levels for Procedure I testa are the values obtained from table 513.4-1. which gives Uie highest test level Mien the known forward acceleration is sttotituted for A in the table. Use this value to test the item in each cf ths six test directions. The acceleration test levels for Froccdisv II tests ш>е obtained in the same manner using table 513.4-II. For helicopters, the highest test level in each of the tables applies regardless of the foi<ward acceleration.

1-3.5 Forward acceleration unknown and the test item orientation Imown. Vtten the forward acceleration of the vehicle is unknown and the orientation cf the test itam is known, the accslsration tssts levels for Procedure I tests are those values obtained from table S13.4-I when the probable forwaad acceleration as listed In the table for the relevant vehicle category is substituted for A. The acceleration test levels for Procedure II test are obtained in the same manner using table 513.4-II (Not applicable to helicopters.)

1-3.6 Forwiard acceleration unknown and the test item orientation unknown. Wien ths forward acceleration is urJcncwn and the orientation of the test item is tsiknown, the acceleration test level for Procedure I tests in the highest value obtained from table 513.4-1 when the probable forward acceleration as listed in the table for the relevant vehicle category is substittited for A. Use this level to test the item in each of the six directions. The acceleration test level for Procedure II tests is obtained in the sane manner \mini table 5I3.4-II. (Not appllcabls tc helicopters.)

1-3.7 FKhter and attack aircrraft. The test levels as determined from tables 513.4-I and 513.4-II are based on accelerations at the center of gravity (CGD of the host vehicle. For fighter and attack aircraft, the test levels in general must be increased for equipment that is located amy from the vehicle CO to account for loads induced by roll and pitch change maneuvers. Roll inpacts the up and down and lateral left and lateral right acceleration loads. Pitch change inpacts the up and down and fore and aft acceleration loads.

1-3.7.1 Roll maneuver loads, up and down test direction. For wing mounted equipment, the test levels for Procedure I (Structural Test) are the up and down levels as determined in table 513.4-1, plus 1.5 times. UN, the additional load induced by roll, wfcere 1.5 Is a safety factor and ДК is conputed as follo e:

Where: d lateral distance of equipment from aircraft CQ in meters $ - absolute valxie of maximum roll acceleration in rad/s (if unknown, use $ 20 rad/s) g 9.80 m/s

For Procedure II (Operational Test), the test levels are the up and down levels as deUrmined in table 513.4-II plus ДМ .

1-3.7.2 Roll maneuver loads, lateral left, and lateral-right jlirectiona. For wing mounted equipment, the test levels for Procedure I (Structural Test) are the lateral left and lateral right levels as detennined in table 513.4-1 or 1.5 times I, the load induced by roll, wiiichever is the higher, vbere 1.5 is a safety factor and ДЫу is conputed as follows:

Mhere: d lateral distance of equipment from aircraft OQ in meters

Ф absolute value of maxlnun roll velocity, rad/s (if uiknown, use

Ф = 5 rad/s) g * 9.80 m/s*

For Procedure II (Operational Test), the test levels are the lateral left and lateral right test levels as determined in table 513.4-II or ЛМу, wiiichever is the higher.

Wiere: d = fore or aft distance of equipment form aircraft OQ in meters

Ф = maximjtn pitch velocity in rad/s (if unknown, use Ф 2.5 rad/s) g = 9.80 m/s*

For Prccsdurs 11 (Operational Test), the test levels are the fore and aft test levels as determined from table 513.4-II or AN.., whichever is higher.

1-3.7.5 Yaw maneuver loads lateral left and right directions. For wrtng-mounted equipment, the test levels for Procedure I (Strixrtural Test) are the lateral left and lateral right levels as determined in table 513.4-1 or 1.5 times K, the load

induced by yaw, whichever is higher, if<her-e 1.5 is a safety factor and Ky is conputed as follows-

roiere: d = lateral distance of equipment fr aircraft CQ in msters

= absolute value of maximum yaw acceleration in rad/sec (if

imknown, use ф = 3 rad/s) g = 9.80 m/s

For Procedure II (Operational Test), the test levels are lateral right test levels as determined in table 513.4-II or Ny, whichever is the higher.

1-3.7.3 Pitch change naneuver load, up and dovai test dtictiona. For fuselage mounted equipment, the test levels for Procedure I (Structural Test) are the xip and dotwn acceleration levels as determined in table 513.4-1 plus 1.5 times Д N, the additional load Induced by pitch change, where 1.5 is a safety factor and is

ccuvuted as с11о г.

Where: d = fore or aft distance of equipment from CQ in meters

$ = maximjtn pitch acceleration in rad/s (if unknown, use = 5 rad/s2 g = 9,80 m/s

For Procedure II (Operational test), the test levels are the up and down levels as determined in table 513.4-1I plus ДЫ-

1-3.7.4 Pitch change лапеиуег load, fore and, aft test directions. For fuselage-inoinited e iir>niBnti the test levels for Procedurs I (Structural Test) are ths fore and aft levels as determined from table 513.4-1 or 1.5 times Hj, the load Indvieed by pitch change, whichever is higher, where 1.5 is a safety factor and Nj, is cooputed as fol lows:

1-3.7.6 Yaw maneuver loads fore and aft test directions. For fuselage-mounted equipment, the test levels for Procedure I {Struetviral Test) are the for© and aft levels as detsrasinsd froni table 513.4-1 or 1.5 tines ДН, the load induced by yaw change, whichever is higher, wiiere 1.5 is a safety factor and All. is conputed as follows:

Mhere: d = fore and aft distance of equipment from aircraft CO in meters C; = absolute value of maxinun yaw velocity in rad/sec (f unknown,

use ii= 4rad/s) g = 9.80 m/s*

For Procedure II (Operation Test), the test levels are fore and aft test levels as detersrinsd from table S13.4-II or K. sSiichevsr is higher.

1-4 SPECIAL COM5IDEKATIONS

1-4. 1 Test,.interruption. If an unscheduled interruption occurs while the test item is at a specified test level, the test should resume at the test level. Фг. test duration tinss should b€ th€ suro cf the tinss at ths test Isvsl ricr to and folloing the interrimtion,

) 1-4.2 Over-acce 1 eration. If the test item is subjected to acceleration loads in excess of the level specified for the test, the test muist be stopped and the test item inspected and functional ly-tested. Based on the inspection and functional test, an erigineering decision should be made as to whether testing should be resuned with the same test item or a new test item.

1-4.3 Sway space measurements. If a piece of equipment is mounted on isolators, the test should be run with the equipment mounted on the isolators and the sway space should be measured to indicate potential interference wdth adjacent equipment.

1-4.4 itcceleration sinjulation. Careful assessment of the fuiction and characteristics of the test item has to be made in selecting the apparatus on which the acceleration tests are to be performed due to the differences in the manner in wbich acceleration loads are prodiiced. There are two types of apparatus that are cornnonly used: the centrifuge and a track/rocket-powered sled combination.

1-4.4.1 Centrifuge, e centrifuge generates aGoeleratlon loads by rotation about a fixed axis. The direction of acceleration is always radially toward the center of rotation of the centrifuge, wihereas the direction of the load induced by acceleration is always radially away from the aocis of rotation. When mounted directly on the test arm, the test item experiences both rotational and translational motion. The direction of the aeeeleration and the load induced Is constant wdth respect to the

a. Junker, V.J. The Evolution of USAFnvironmentaltesting. October 1965. AFFDL-TR-e5-197. DITC number AD-625-543-

test item for a given rotational speed, but the test item rotates 360 degrees for each revolution of the arm. Certain centrifuges have couiter-rotating fixtures mounted on the test arm to correct for rotation of the test Item. With this arrangemsnt, the test item Snlntains a fixed direction nth respect to space, it the direction of the acceleration and the Induced load rotates 360 degrees around the specimen for each revolution of the arm. Another characteristic is that the acceleration and induced load aire in direct proportion to the distance from the center of rotation. This necessitates the selection of a centrifuge of adequate size so that the portions of the test item nearest to and furthest from the center of rotation are sxibjected to not less than 90 percent or more than 110 percent, respectively, ef the specified tsst level.

1-4.4.2 Track/rocket-powered sled. The track/rocket-powered sled arrangement generates linear acceleration in the direction of the sled acceleration. The test item mounted on the sled is uniformly subjected to the same acceleration level as the sled experiences. The acceleration test level and the time dxiration at the test level is dependent ipon ths ler,gth of ths track, ths pcsr of ths rocket, and the rocket charge. The sled track generally mil produce a slgnifleant vibration environment due to track roughness. Typical ly this vibration is Significantly more severe than the normal service use environment. Careful attention to the attachment design may be needed to isolate the test item fi4>m this vibration environment. In performing Procedure II tests, the s\jpport equipment necessary to operate ths tsst itsir. is tsounted on ths sled arid traverses the track with the test item. This requires the use of self-contained power units and a remote control system to operate the test item while traversing the track. Telemetering or ruggedlzed instrumentation is required to measure the performance of the test item while it is exposed to the test load.

kr№

Vltere: * t level tobe applied

К 1.12 X 10 for metric calculations

R = radial distance from the center of rotation to the moimting

location cn centrifuge sjm in meters N = centrifuge arm revolutions per minute

The orientation of the test item on the centrifijge for the six test directions is as follows:

a. Fore. Front or forward end of test item facing toward center of centrifuge.

b. Aft. Reverse item 180 degrees from fore position=

c. Ud: Top of test item facing tomrd center of centrifrjge.

NETHOD 513.4 ACCELERATION SECTION II

II-l APPARATUS. Either a centrifuge of adequate size or a traok-rooket-poveered sled arrangement may be used A centrifuge is reconnended for all Procedure I (Structural Test) and most of Procedure II (Operational Test) evaltiations. A track/rocket-powered sled arrangement is recomnended for Procedure II evalviations when strictly linear accelerations are required.

II-2 PBCTABATION TOR TEST

II-2.1 Inspections. The test item shall be configured for service application. The item should be visxjal ly inspected for evidence of mishandling and in-transit damage. Any damage observed must be noted on a pretest data sheet and nay be cause for rejection cf the item for tests Sufficient dimensional nBaSurements of the item shall be obtained to provide a reference guide for the evaluation of physical damage that m be induced during the tests.

II-2.2 Mounting of the test item. The test item shall be mounted on the test apparatus ijslng the hardware that is normally used to mount the item in its service installation.

II-2.2.1 Centrifugerounting. For centrifuges, the location for the teat item is normally determined by measurement from the center of rotation of the centrifuge to the looatlon on the centrifuge arm that will provide the g level established for the test. The test item is mounted so that its geometric center is at the location on the arm determined for the g level. G levels may be calculated as follows.

a. uovei. Reverse item ISO degrees from Up p>o8itiOn.

e. Lateral left: Left side of teat item facing toward center of centrifuge=

f. Lateral right: Right side of test item facing toward center of centrifuge.

After the test item is properly oriented and mounted on the centrifuge, шёагигётвпъв and ealeulationa oust be mde to assxs-e that the end of the test item nearest to the center of the centrifuge will be subjected to no lees than 00 percent of the g level established for the test. If the g level ie foind to be less than 90 percent of the established g level, the test item nust be mounted further out on the centrifuge arm aлd the rotational speed adjusted accordingly or a larger centrifuge used so that the end of the test item nearest to the center of the centrifuge is subjected to at least 90 percent of the established g level. Hovisver, the opposite end of the test itsss (ths snd farthest from ths center of the centrifuge) should not be subjected to over 110 percent of the еаЬаЫ iahed g level. For large test items, exceptions should be made for load gradients based on the existing availability of large centrifuges in cormercial or government test f aici 1 ities .

II-2.2.2 Pcket-powgred g 1 sd..mpunting. For rocket-powered sled mounting, th© test item and associated test fixtwe or apparatua shall be inoisited an the sled platform in accordance writh the controlled acceleration direction of the sled. (The test fixture or apparatus should have been designed to isolate sled vibrations from the test item.) Since the sled and test item experience the same g levels, only the orientation of the test item on the sled is critical. The orientation of the test

513.4-1 and the controlled acceleration direction of tbe sled for the six test directions.

11-2.3 Functional pretest. After the test item is mounted on the test apparatus, a conplete functional test shall be made on the test item to assure that the test item complies with the specification requirements. Record functional performance, observed data, and other pertinent information. Failure of the itm to conply to specifications is cause for rejection for test.

For Procedure I (Structural Test). the functional pretest may be performed prior to mounting the test item on the test apparatus. However, for Procedure II (Operational

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the test apparatus to atssure that the test item is properly installed for operation during the Procedure II tests.

II-3 PROCEDURES

II-3.1 Procedure I - 5trix:tural test. Bring the centrifiige to the speed required to indues ths specified g level in ths test item as determined from 1=4 and table 513.4-I for the paur-ticular test item orientation. Maintain this g level for at least one

II-4 INTOBWRTIOW TO BE ЯЕСОКРЫР

a. Test item identification (manufactrirer, serial nxasfcer, etc.).

b. Pretest inspection observations and dimensional meastirements made of the test item.

c. Pretest (lerational periormance data obtained from the test item.

d. Test procedtA>e nijnber, test appvatus, test item orientation, test level, and time duration at the test level.

e. For Procedure II tests, the operational performance data of the test item ivile it is under load.

f. Post test inspection and operational test of the test item.

g. Failure analysis or deviations from SF>ecification, if appropriate.

minute after the centrifuge rpm has stabilized. Bep>eat this test procedure for the remaining five test directions. Upon conpleting the tests in the six test directioriS, ths item should be functiorial ly tested as specified in II-2.3 and inspects as specified in 11-2Л,

II-3.2 Procedure,!! - Operational test.....(centrifuge). Turn on the test item and

place it in its operational mode. With the test item operating, bring the centrifuge to the speed required to indix the specified g level in the test item as determined from 1-4 and table 5i3.4-II for the particular test item orientetioa. Maintain this g level for at least one minute after ths centrifuge г;нп has stabilized. (Л:еск the functional performance of the test item before, during, and after the test and record the results. Bepeat this test procedure for the five remaining test directions. \}pon conopleting the tests in the six test directions, the test item shall be inspected according to I1-2.1

11-3.3 Procedure JI - Operational testjtrack/rocket-powered sled). Turn on the test item and place it in its ci2eraticr.al isode. With the test item operatir.g, accelerate the sled to the level required to induce the specified g level in the test item as determined fx>om 1-4 and table 513.4.II for the paurtlcular test item orientation. Check the functional performance of the test item before, during, and after the test and record the results. Due to the dynamic limitations of track and Sled facilities, additional test т\жш wmy be required to adequately demonstrate acceptable perforssance of the test item ¥lle \sider the test loading, Bepeat this test procedure for the five remaining test directions. Upon conpleting the tests in the six test directions, the test item shall be inspected according to 11-2.1.

METHOD 514.4 VIBRATION SECTION 1

Page

I-l PUBPOSE.......................... 514.4-1

1-2 И*vIЮfaEЖrГAL EFFECT................... 514.4-1

1-3 GLDELIЙES FOR DETERMINING TEST РВОСЕОШШЗ

AND lT CMTOITIONS................... 514.4-2

1-3.3 THANSPORTATION VIBRATION................. 514.4-4

1-3.4 APPLICATION VIBRATION.................. 514.4-14

1-4 SPECIAL CONSIDERATIONS .................. 514.4-41

1-5 RteEKhJJCES........................ 514.4-48

SECTION II

II-l APPARATUS......................... 514.4-53

II-2 PREPARATION FOR TEST................... 514.4-59

II-3 PROCEDURES ........................ 514.4-50

11-4 INFORMATION TO BE RECORDED................ 514.4-63

.ANNEX A.............................. 514.4-A65

I-l PURPOSE. Vibration testing is performed to determine tbe resistance

of equipment to vibrational stresses expected in its shipment and application

environments.

1-2 ENVIBONIiiENTAL EFFECTS. Vibration can cause:

a. Wire chafing.

b. Loosening of fasteners.

c. Intermittent electrical contacts.

d. Touching and shorting of electrical parts.

e. Seal deformation.

f. Conponent fatigue.

g. Optical misalignment.

h. Cracking and ritiiring.