MIL-PRF-87260B(USAF)
4.5.5 Tensile strength and ultimate elongation tests.
Tension tests, including tensile strength and ultimate elongation, shall be conducted in
accordance with ASTM D3574 (Test E), except that the initial jaw separation shall be 2.0
inches. A 2.5-inch jaw separation may be used for consistency with other products, however,
data must be provided in the qualification report showing the correlation between the two grip
lengths. For elongation measurements there are two approved techniques, benchmarks and
crosshead travel. The rate of travel of the power actuated grip shall be 20 ±1 inches per minute
and shall be uniform at all times. The specimen die to be used shall be in accordance with
Figure 1 of ASTM D3574 entitled "Die For Stamping Tension Specimens." The approximate
size of the dry specimen shall be 5.5 inches x 1 inch x 0.50 inch thick. The specimen thickness
dimension shall be between 0.500 and 0.600 inches. For all but qualification, three specimens
per sample shall be tested. If any value deviates more than 20.0 percent from the average, two
additional specimens shall be tested and the average of all five reported. For qualification, 10
specimens shall be tested and all values reported. In addition, a copy of the recorded traces
shall be included in the test report. The tensile strength shall be reported in pounds per square
inch, and ultimate elongation in percent. Tension specimens shall be taken from the upper half
of the test section, and the orientation shall be such that the 1/2-inch dimension (5.5 inches) is
always in the machine direction (see 6.5.4). For special fuel-wet tension tests, the specimens
shall be measured on the dry specimen prior to test fluid exposure and recorded for later usage.
When testing the specimen, it should be removed from the fluid prior to tension tests, drained,
and immediately tested. Do not allow the sample to air dry, as it will affect the test results.
Original dry specimen data shall be used as a baseline for calculating the percent loss in wet
tensile strength for tests in 4.5.16b.
4.5.6 Tear resistance test.
Three specimens shall be tested in accordance with ASTM D3574 (Test F) using a crosshead
speed of 20 ±1 inches per minute. Dry specimen size shall be 6 inches x 1 inch x 1 inch where
the 6-inch dimension is in the machine direction and the slit cut is parallel to the direction of rise.
The tear resistance shall be reported in pounds per lineal inch of thickness. Specimens shall be
cut from 1 inch thick slabs of material. For fuel-wet tear resistance tests (4.5.16b), the
specimen shall be tested immediately after removal from the fluid. Original dry specimen data
shall be used as a baseline for calculating the percent loss in wet tear resistance.
4.5.7 Constant deflection compression set test.
Three specimens shall be tested in accordance with Method B of ASTM D3574 (Test D) at a 50
percent deflection. Sample size shall be 4 inches x 4 inches x 3 inches. The three specimens
shall be cut from the same 3-inch thick slab located in the middle of the test section (bun height)
and adjacent to the specimens used in the compression load deflection test specified in 4.5.8.
The specimens shall be tested (compressed) in the direction of rise (3-inch dimension). Results
for all specimens shall be reported in percent of original thickness.
4.5.8 Compression load deflection (CLD) test.
Three specimens shall be tested in accordance with ASTM D3574 (Test C) at the 25 percent
and 65 percent deflection level after 1 minute at each deflection point. Specimen size shall be 4
inches x 4 inches x 3 inches and taken near the middle of the bun height such that the 3-inch
dimension is in the direction of material rise. The rate of compression (deflection) shall be 2
inches per minute. New material shall be aged for a minimum of 96 hours following thermal
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