Accession Number:

AD0258552

Title:

SYSTEMATIC AXIAL LOAD FATIGUE TESTS USING UN-NOTCHED ALUMINUM ALLOY 2024-T4 EXTRUDED BAR SPECIMENS

Descriptive Note:

Corporate Author:

TORONTO UNIV (ONTARIO) INST FOR AEROSPACE STUDIES

Personal Author(s):

Report Date:

1960-05-01

Pagination or Media Count:

1.0

Abstract:

A series of axial-load fatigue tests were performed on Al Alloy 2024-T4 extruded bar, using a mean tensile stress of 16 ksi. The basic single-level SN relation was established using 9 specimens at each of 15 alternating stress amplitudes. The statistical behavior of the single-level fatigue endurances at the knee of the SN curve was discovered to be consistent with the rise and decay respectively of 2 endurance distributions, apparently representing the action of 2 different fatigue mechanisms. The logendurance population during transition became bimodal in nature, with the first distribution a continuation of the log normal distributions at stress amplitudes above this region. An extensive 2-level test program was carried out. By this procedure, areas of severe damage accumulation were delineated, as were areas of so-called healing which occur at certain high stress levels 0.1 proof stress, and at high numbers of cycles at low stress levels. Author

Subject Categories:

Distribution Statement:

APPROVED FOR PUBLIC RELEASE