FED-STD-228A
4.4 The width of the specimen shall be determined as described in method 1411 except that
measurements shall be made at 5 places equally spaced along the length of the portion of the specimen
that is to be placed between the grips of the testing machine, and the minimum value recorded as W.
4.5 The ratio of the clearance between the grips of the testing machine to the width of the specimen shall
be not less than 5 to 1 and not more than 10 to 1 at the start of the test. The specimen shall be placed in
the machine with the long dimension parallel to and the short dimension perpendicular to the direction of
the applied force. The speed of the power-actuated grip of the machine shall be 12 inches ± 0.5 inch per
minute. The machine shall be set in motion and the force required to break the specimen read from the
dial scale, or recorder, and the value recorded as F.
4.6 If the specimen skips between the jaws, breaks in or at the edges of the jaws, or if for any reason
attributable to faulty technique an individual measurement falls markedly below the specified minimum,
such individual result shall be disregarded and another specimen shall be tested.
5. RESULTS
5.1 Calculation. The tensile strength of the specimen shall be calculated as follows:
Tensile strength, p. s. i., = _F_
TW
where:
F=the breaking force of the specimen, pounds
T=the minimum thickness of the specimen, inch
W=the minimum width of the specimen, inch
5.2 Unless otherwise specified in the detail specification, two specimens from each tape selected shall
be tested.
5.3 The tensile strength of the tape shall be the average of the results obtained from the specimens
tested.
5.4 The tensile strength of each tape tested shall be recorded to the nearest 10 pounds per square inch.
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