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National Advisory Committee for Aeronautics, Technical Notes - Tensile and Pack Compressive Tests of Some Sheets of Aluminum Alloy, 1025 Carbon Steel, and Chromium Nickel Steel

A knowledge of the tensile Iand the compressive prop-I , ”“r
design of many parts of aircraft structures. -The compres—
sive properties are of particular impIortanc.e because the
design of most ofI these sItructures is dictated by comprés—
sive rather than tensile strength.

A serious difficulty in obtaining the compressive
properties of thin sheet metal is'the.tendency o£.the
sheet to buckle at“a'stress well below the yield
strength. This difficulty is overcome to a large extent
by the.pack method developed in recent years at the
National Bureau of Standards with the support of the
National Advisory Committee for Aeronautics and the
Bureau of Aeronautics, Navy Department (references 1 and
2). Preliminary tests of a number of sheet materials
used in aircraft showed that large differences may exist
between the tensile and compressive properties. There
were also appreciable differences for specimens taken
lengthwise of the sheet and those taken crosswise.

For this reason it seemed desirable to obtain the
tensile and compressive properties of sheet metals'used
in aircraft, to evaluate these differences, and to pro—
vide an experimental background for a study and classi—
fication of stress—strain data. The National Advisory
Committee for Aeronautics accordingly requested the
National Bureau of Standards to carry out such an inves-
tigation.

The present paper gives the results of tensile and
pack compressive tests on specimens taken from some
aluminum alloy and steel sheets in the direction of the
length of the sheet and in the direction of the width.
These results are presented for purposes of -comparison
rather than for use as typical properties of the materi—
als. It is hoped that a continuation of this study will
result in obtaining parameters or analytical expressions
that will _provide a better description of the stress—
strain relationship of some of these materials than those
_in use at present.

The description of the sheet materials is given in
table I. The sheets having as their source NACA were
surplus sheets fro.m other investigatibns for the National
Advisory Committee fo_r Aeronautics (references 3, 4, and
5). The sheets having as their source Navy Department
were materials submit.te d from time to time by the Bureau
of Aeronautics, Navy Department, for mechan_ical tests.
The authors take this dpportu'nity to thank thle Navy
Department for permissiOn'to include this material in the
present paper.