NATIONAL BUREAU OF STANDARDS REPORT

U783

STATIC LOADING TESTS OF AN

Ao Go A. EXPENDABLE TOP RUNWAY LIGHT HEAD

ASSEMBLY WITH A GLASS COVER

L. K. Irwin

To

Equipment Laboratory

Wright Air Development Center

Department of the Air Force

<NBS>

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS
U. S. DEPARTMENT OF COMMERCE

Sinclair Weeks, Secretary

NATIONAL BUREAU OF STANDARDS

A. V. Aslin, Director THE NATIONAL BUREAU OF STANDARDS

The scope of activities of the National Bureau of Standards at its headquarters in W ashington,

D. C., and its major field laboratories in Boulder, Colorado, is suggested in the following listing of

the divisions and sections engaged in technical work. In general, each section carries out specialized

research, development, and engineering in the field indicated by its title. A brief description of

the activities, and of the resultant reports and publications, appears on the inside back cover of

this report.

W ASHINGTON, D. C.

Electricity and Electronics. Resistance and Reactance. Electron Tubes. Electrical Instru- ments. Magnetic Measurements. Process Technology. Engineering Electronics. Electronic

Instrumentation. Electrochemistry.

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Enameled Metals. Concreting Materials. Constitution and Microstructure.

Building Technology. Structural Engineering. Fire Protection. Heating and Air Conditioning. Moor. Rool. and Wall Coverings. Codes and Specifications.

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Analogue Systems. Applications Engineering. • Office ol Basic Instrumentation • Office of Weights and Measures

BOULDER, COLORADO

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Extreme High frequencv and Noise. Microwave Frequency and Spectroscopy. Microwave

Gircuil Standards.
NATIONAL BUREAU OF STANDARDS REPORT

NBS PROJECT NBS REPORT

0201-20-2331 July 1956 I4.783

STATIC LOADING TESTS OF AN

A. G. A« EXPENDABLE TOP BUNWAY LIGHT HEAD

ASSEMBLY WITH A GLASS COVES

L« Ko Irwin

Engineering Mechanics Section

Mechanics Division

To

Equipment Laboratory

Wright Air Development Center

Department of the Air Force

NBS Lab. No. 6*4/2-lj.-3

<NBS>

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

The publication, reprinting, or reproduction of this report in any form, either in whole or in part, is prohibited

unless permission Is obtained in wrltingfrom theOffice of the Director, National Bureau of Standards, Washington

25, D. C, Such permission is not needed, however, by a Government agency for which a report has been specifically prepared if that agency wishes to reproduce additional copies of that particular report for its own use,

STATIC LOADING TESTS OP AN

Ac Gc A. EXPENDABLE TOP RUNWAY LIGHT HEAD

ASSEMBLY WITH A GLASS COVER PLATE

by

L. K« Irwin

1, SAMPLE

An expendable top runway light head assembly with a 3/4-

inch thick glass cover plate, manufactured by the American

Gas Accumulator Division, Elastic Stop Nut Corporation, was

submitted for static load tests o The light head assembly

represented parts of a prototype runway marker light. The

steel ring in which the 7-inch diameter glass plate was

mounted was fabricated by the "Hydraform" process. The various components submitted for test were disassembled after the

tests and are shown in figure 1.

2 0 TESTS AND PROCEDURES

Four static load tests were made on the light head assembly* For the first test, the load was applied through a 20 x

4*4, 10-ply rating, aircraft tire with the air pressure at no

load measured to be 155 lb/in? The tire and assembly are

shown in the loaded condition in figure 2.

In the second test, the load was applied through a 1-inch

thick x 6-inch diameter steel disc centered on the glass plate

with a matching 3/16-inch thick rubber pad between the steel

disc and the glass plate.

A 3/4- inch thick by 7-inch diameter steel disc on a

matching l/4-inch thick rubber pad was centered on the glass

plate with the 3/l6-inch pad retained in place from the previous test for the third test. The rubber pads were in contact with item I and the glass plate in item K shown in

figure 1.

For the fourth test, items G, H, I and J were removed

and the load was applied through the 7-inch diameter steel

disc and matching l/4-inch pad centered on the glass plate.
'

: - ;• i .

'

' '

,

.

*

- - i

.

:

' •

' ; IS

'

'

-
Lab. No. 6.l}./2-lj.«3 page 2

Continuously increasing compressive loads were applied

in tests 1 and 2 until the predetermined loads were reached,

then the loads were removed quickly® For tests 3 and [|., the

loads were applied as for the previous tests but loading was

stopped after failure of components was indicated by pronounced decreases in the loading rates.

3. RESULTS

Four static load tests were made on an A. G. A. expendable top light head assembly. The results of these tests are

given in table 1.

Table 1 - Static Load Tests of an

Head Assembly.

A 0 Go A 0 Expendable Top Light

Test

No.

Loading

medium

Maximum

load

Unit

load* Remarks

lb lb /in?

1 20 x 1^. 1^ tire 9,100 Snapping sound at 5600

lb, probably from the

plastic ring, item H in

figure 1

2 6 -in. diameter

steel disc and

rubber pad

14,800 524 No visible damage

3 7 -in. diameter

steel disc and

rubber pads

15,000 390 Top gasket, item J in

figure 1, extruded toward

center of glass plate

4 7=*in. diameter

steel disc and

rubber pad

25,500 663 Bottom gasket under glass

plate, item K in figure 1

extended toward center of

glass plate

* Ratio of maximum load to area of loading disc
I .
Labo No® 6 • 4/

page 3

The damaged top gasket is shown in figure 3 immediately

after test 3 ° There was a marked decrease in the rate of

loading at l!4.,600 lb without a corresponding change in the

rate of motion of the testing machine heado Loading was continued to a maximum load of 15 S 000 lb and then removed quickly <» The bottom gasket on which the glass plate Was seated

is shown in figure i4- extruded toward the center of the plate

after sustaining a compressive load of 25^500 lb after which

there was a pronounced drop in the indicated load 0 No? additional load was applied

For the Director

,

Bo L® Wilson* Chief*

Engineering Mechanics Section,

Division of Mechanics®

Washington, D, C«

July 1956
s '


Figure 2y The light head assembly sustaining a load

applied through a 20x4*4 aircraft tire*

of 9 P 100 lb

Figure

3©

The

partially

disassembled

light

head

components

after

test

3*

The

top

gasket

was

extruded

toward

the

center

of

the

glass

plate

i

Figure 4. The glass plate and mounting ring assembly after test

4. The bottom gasket extruded toward the center of

the glass plate after sustaining a maximum load of

25,500 lb.

THE NATIONAL BUREAU OF STANDARDS

Functions and Activities

The functions of the National Bureau of Standards are set forth in the Act of Congress, March

3, 1901, as amended by Congress in Public Law 619, 1950. These include the development and

maintenance of the national standards of measurement and the provision of means and methods

for making measurements consistent with these standards; the determination of physical constants

and properties of materials; the development of methods and instruments for testing materials,

devices, and structures; advisory services to Government Agencies on scientific and technical

problems; invention and development of devices to serve special needs of the Government; and the

development of standard practices, codes, and specifications. The work includes basic and applied

research, development,' engineering, instrumentation, testing, evaluation, calibration services, and

various consultation and information services. A major portion of the Bureau’s work is performed

for other Government Agencies, particularly the Department of Defense and the Atomic Energy

Commission. The scope of activities is suggested by the listing of divisions and sections on the

inside of the front cover.

Reports and Publications

The results of the Bureau’s work take the form of either actual equipment and devices or published papers and reports. Reports are issued to the sponsoring agency of a particular project

or program. Published papers appear either in the Bureau’s own series of publications or in the

journals of professional and scientific societies. The Bureau itself publishes three monthly periodicals, available from the Government Printing Office: The Journal of Research, which presents

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which provides data for determining the best frequencies to use for radio communications throughout

the world. There are also five series of nonperiodical publications: The Applied Mathematics

Series, Circulars, Handbooks, Building Materials and Structures Reports, and Miscellaneous

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Information on the Bureau’s publications can be found in NBS Circular 460, Publications of

the National Bureau of Standards ($1.25) and its Supplement ($0.75), available from the Superintendent of Documents, Government Printing Office. Inquiries regarding the Bureau’s reports and

publications should be addressed to the Office of Scientific Publications, National Bureau of

Standards, Washington 25, D. C.