• Version
• 131 Downloads
• 1.31 MB File Size
• 1 File Count
• January 31, 2017 Create Date
• January 31, 2017 Last Updated

National Advisory Committee for Aeronautics, Technical Notes - Creep Behavior of Structural Joints of Aircraft Materials Under Constant Loads and Temperatures

The results of 55 creep and creep-rupture tests on structural Joints
are presented. Mbthods are described by which the time to rupture, the .
mode of rupture, and the deformation of Joints in creep may be predicted.
These methods utilize creep data on the materials of the Joint in ten-
sion, bearing, and shear. The accuracy of these methods is within the
scatter of the materials creep data.

Aerodynamic heating effects require that aircraft structures for
high—speed flight be designed so that excessive creep deformation and
creep rupture will not occur during the design lifetime of the structure.
In order to execute properly such designs, an understanding of the creep
behavior of structures is necessary.

A limited study by the Aluminum Company of America of the creep of
riveted joints, which involved the testing of only four specimens,_ref—
erence 1, showed that the creep of a Joint can be considerably greater
than the tensile creep of an unriveted sheet. This study aroused the
interest of the various aircraft establishments in this country in the
need for obtaining a more thorough understanding of the creep of struc-
tural Joints. To fill this need, the National Advisory Committee for
Aeronautics sponsored a more comprehensive investigation of the creep
of structural Joints at the National Bureau of Standards, reference 2.

This investigation corroborated the Alcoa result that the creep of a
joint can be considerably greater than the tensile creep of an unriveted
sheet. Furthermore, no correlation between the creep of a Joint and the
tensile creep of an unriveted sheet was found. Several_§mpirical design
criteria were proposed, but the number of different Joint designs inveSti—
gated was insufficient to verify completely these criteria.

The purpose of this report is to describe an investigation which
was undertaken as an extension of that reported in reference 2. The
present investigation was conducted at the NBS under the sponsorship and
with the financial assistance of the-NACA. It—involved‘the testing of
additional joint designs, with the aim of establishing design criteri
for structural joints in creep.