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National Advisory Committee for Aeronautics, Report - Investigation of the Compressive Strength and Creep Lifetime of 2024-T3 Aluminum Alloy Plates at Elevated Temperatures

The results of elevated-temperature compressive strength and
creep tests of 2024—T3 (formerly 248—13) aluminum-alloy
plates supported in V—grooves are presented. The strength-test
results indicate that a relation previously developed for predict-
ing plate compressive strength for plates of all materials at
room temperature is also satisfactory for determining elevated—
temperature strength. Creep-lifetime results are presented for
plates in the form of master creep-lifetime curves by using a
time-temperature parameter that is convenient for summarizing
tensile creep-rupture data. A comparison is made between
tensile and compressive creep lifetime for the plates and a
method that makes use of isochronous stress-strain curves for
predicting plate-creep failure stresses is investigated.

Since plates are one of the most important load-carrying
components in the structure of an aircraft, an understanding
of their elevated-temperature strength and creep behavior is
becoming increasingly important. At the present time very
little published information (ref. 1) is available on the experi-
mental maximum strength of plates at elevated temperatures
and no data have been found on experimental creep behavior
of such members. The purpose of the present investigation
was to obtain experimental data on both compressive strength
and creep lifetime of 2024—T3 (formerly 248—T3) aluminum-
alloy plates at elevated temperatures. In this study plates
of width-thickness ratios ranging from 20 to 60 were tested to
determine maximum compressive strength at temperatures
ranging from room temperature to 600° F. Creep tests were
made at 400° F, 450° F, and 500° F with a similar range of
width—thickness ratios. In all tests the unloaded edges of
the plates were supported in V-grooves.

The results obtained in the compressive-strength tests are
analyzed to determine whether a materials parameter, shown
previously to be applicable for correlating room-temperature
plate strength with material properties (ref. 2), is also appli-
cable at elevated temperatures.