MIL-D-87030B(SH)
of the aging interval, the specimens shall be cooled at room temperature on a
flat surface and allowed to rest not less than 4 hours before determination of
shrinkage. The average shrinkage in each direction shall be calculated as
follows and reported to the nearest 0.1 percent:
Percent shrinkage = O - A x 100
0
Where O = Original length or width (inches).
A = Length or width after aging (inches).
4.6.1.3 Density. Five specimens each 2 inches square shall be weighed
separately to the nearest 0.001 gram on an analytical balance. The thickness
of each specimen shall be determined in accordance with ASTM D 1056 and the
following formula shall be used to determine density:
D = 0.95 x W
T
3
Where D = Density in lb/ft .
w = Sum of the weights of the five specimens (grams).
T = Sum of the thicknesses of the five specimens (inches).
4.6.1.4 Elongation. An incline plane type of machine (for example I-P-4
or similar type) with a suitable autographic recording device shall be used.
Specimens of the fabric shall be cut 4 by 6 inches with the long direction
parallel to the direction to be tested. The specimen shall be evenly aligned
without tension or slack in the 1- by 3-inch clamps set 2 inches apart. The
machine shall run through two complete cycles, proceeding to its maximum
depression so as to exert a 5-pound tension. Five specimens, each containing
different wales and courses shall be tested, using individual recorded
elongation graphs. The average stretch of five specimens for each direction
shall be measured at the peak of the last recorded cycles, in a line perpen-
dicular to the horizontal zero axis and reported to the nearest percent.
4.6.1.5 Tensile stress. The test specimen shall be dumbbell shape and cut
using die "C" as specified in ASTM D 412. Specimens shall be cut in the length
direction of the sample. The tensile stress test shall be made on a power-
driven machine equipped with suitable jaws to firmly hold the specimen in place
while they are separating at 20 ± 2 inches per minute, The machine shall be
equipped with a recording device so that the applied force is accurately measured
during the extension of the specimen, The test specimen shall be conditioned
for 4 hours in a conditioned atmosphere of 65 percent relative humidity and
70°F. Dumbbell specimens shall be marked with a marker having a marking edge
1/16 inch in thickness. The sample shall be under no tension at the time it
is marked. Marks shall be placed equidistant from its center and perpendicular
to its longitudinal axis. The center of the marks shall be 1.0 ± 0.003 inch
apart. Set the grip separation at 2.5 inches minimum. Place the dumbbell
tabs in the grips of the testing machine, using care to adjust them symmetri-
cally in order that the tension will be distributed uniformly over the cross
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