Accession Number:

AD0256075

Title:

INVESTIGATION OF THREE ANALYTICAL HYPOTHESES FOR DETERMINING MATERIAL CREEP BEHAVIOR UNDER VARIED LOADS, WITH AN APPLICATION TO 2024-T3 ALUMINUM-ALLOY SHEET IN TENSION AT 400 DEGREES F

Descriptive Note:

Corporate Author:

NATIONAL AERONAUTICS AND SPACE ADMINISTRATION WASHINGTON D C

Personal Author(s):

Report Date:

1961-05-01

Pagination or Media Count:

1.0

Abstract:

Three existing hypotheses are formulated mathematically to estimate tensile creep strain under varied loads and constant temperature from creep data obtained under constant load and constant temperature. The hypotheses investigated include the time-hardening, strain-hardening, and lifefraction rules. Predicted creep behavior is compared with data obtained from tensile creep tests of 2024-T3 aluminum-alloy sheet a 400 F under cyclic-load conditions. A simplified method of calculating creep strain under varied loads is presented on the basis of an equivalent stress, derived from the life-fraction rule, which reduces the varied-load case to a constant-load problem. Creep strain in the region of interest for structural design and rupture times, determined from the hypotheses investigated, are in fair agreement with data in most cases, although calculated values of creep strain are generally greater than the experimental values because creep recovery is neglected in the calculations. Author

Subject Categories:

Distribution Statement:

APPROVED FOR PUBLIC RELEASE