ORNL-1771 - Oak Ridge National Laboratory

ANP QUARTfRLY PROGHESS REPORT
As before, the stress ratio is independent of the
diameter a of the piston rod. Since the piston rod
is in compression, however, it should be made
large enough to prevent buckling. The bleed lines
shown in Figs. 7.4~ and b should be kept open
during testing to assure that no pressure leaks
from the large-diameter chamber to the smaller one.
A test rig has been built that imposes the con-
dition rrt/oa = no. Strain measurements made with a
strain-gage bridge fastened to the gage area showed
that the friction in the system was negligible and
that the only active stress was tangential. A speci-
men is now being tested at 1500°F under this stress
cond it ion.
There has been considerable speculation as to
the possibility of a difference in the rote of cor-
rosive attack of fused salts in contact with lnconel
under tensile stresses as compared with lnconel in
compression. In order to observe any difference, it
is desirable that the compressive and tensile
stresses be imposed on the same specimen and be
of the same magnitude. One approach to this prob-
lem is to test a specimen under pure bending con-
ditions. This would ensure that the magnitude of
the maximum tensile stress would always be equal
to that of the maximum compressive stress during a
given test. An apparatus which would produce this
effect was also designed by Jordan, and a specimen
is now being tested in o fused salt medium. A
drawing of the specimen and the loading apparatus
is presented in Fig. 7.5. If it is assumed that no
friction occurs between pins C and D and the
specimen, all the force P wi II be transmitted across
section 1-1 by the link I_ and no axial force will
exist in the specimen. Likewise, since link L is
loaded axially, it cannot transmit any bending
moment and therefore the specimen must resist any
bending moment existing across section 1-1. The
force in link L will be equal to P to satisfy the
equilibrium of forces. The bending moment in the
specimen will then be equal to the product of P and
the horizontal distance between the centers of pins
A and 6. In order to minimize variations inthe
bending rrioment (and therefore stresses) in the
specimen during a test, the horizontal distance
between A and B should be held as nearly constant
as possible. Since the specimen deformsunder load,
the ends will rotate and some change in the distance
AB must occur. In order to minimize the change,
the pins A and B are placed with their centers
slightly above and below, respectively, a horizontal
116
P
SP
UYCLASSIFIED
ORNL-LR-DWG 2852
SPECIMFN
Fig. 7.5. Apparatus for Testing a Sheet Specimen
Under Pure ending Cod it ions.
diameter. This will allow some rotation to occur
with very little change in the horizontal distance.
The apparatus shown in Fig. 7.5 has been con-
structed. Strain gages were placed on the tension
and compression sides of a specimen, and load was
applied. In the range of loads contemplated in a
creep test, the tensile and compressive strains
were essentially of the same magnitude; thus very
little friction existed between the pins and the
specimen.
HIGH-CONDUCT IV ITY -F IN
SODIUM-TO -AIR RAD !AT0 R
Developmental work has continued on a sodium-
to-air radiator with fins of a high-thermal-conductivity
material. The developmental effort includes in-
vestigations of materials with high thermal con-
ductivity, the development and testing of brazing