Correlation of creep-buckling tests with theory Page: 2 of 41
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3 1176 01434 3975
NACA RM 56C20- -
NATIONAL ADVISORY COMMITTEE FOR AFRONAUTDS
RESEARCH MEMORAND
CORRELATION OF CREEP-BUCKLING TESTS WITH THEORY
By Sharad A. Patel, Joseph Kempner, Burton Erickson,
and Abol H. Mobassery
STIMMARY
The results of short-time creep-buckling and creep-bending tests of
2024-T4 aluminum-alloy columns of slenderness ratio ll are presented.
The tests were performed at 6000 F, and strain measurements were taken
with high-temperature electric-resistance strain gages. A description
of the development of the gages is given in an appendix. The column
tests show that the critical time decreases much more rapidly with
increasing load than with increasing initial deviation from straightness.
The bending tests indicate that the steady creep rate of the curvature
is a simple power function of applied moment. These latter results,
together with a previously derived creep-buckling theory, are used to
develop a semiempirical formula suitable as a guide for the determination
of the critical time for columns.
INTRODUCTION
When a load-carrying structure is used at elevated temperatures,
its structural elements deform with time even though the external loads
may not change. If the structure contains components which are subjected
to compressive loads, the danger of a local or general instability exists
because of the interaction between the loads and creep deformations. The
need for suitable design criteria covering such failures is apparent.
Unfortunately, such problems are extremely complicated and generally not
amenable to simple calculations . Such is the column problem. Notwith-
standing, several more or less approximate column creep-buckling theories
have been published in the past few years (for example, refs. I to 6).
Some appropriate column tests have also been reported (for example,
refs. 4 and 7 to 11). In reference 10 a fairly comprehensive test pro-
gram, the results of which were presented in the light of the theoretical
results of reference 2, facilitated the construction of column curves for
7075-T6 aluminum-alloy columns. These curves appear to be satisfactory
for design purposes in the temperature range 300 to 6000 F.
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Patel, Sharad A.; Kempner, Joseph; Erickson, Burton & Mobassery, Abol H. Correlation of creep-buckling tests with theory, report, May 23, 1956; (https://digital.library.unt.edu/ark:/67531/metadc62222/m1/2/: accessed April 25, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.