FED-STD-228A
4.3 The specimen shall be placed in the testing machine so that the bench marks are between the spools
when spool grips are used. When using the usual wedge-type grip there shall be a distance of at least 1
inch between each bench mark and the adjacent grip. The speed of the power-actuated grip shall be 10
± 2 inches per minute under no load.
4.4 After rupture of the specimen the breaking force shall be read from the dial recorder, or scale to the
nearest pound and the value recorded as F. If the specimen breaks outside the bench marks or within 1
inch of either bench mark, the results shall be discarded and additional specimens tested until breaks are
obtained within the prescribed portion.
4.5 The broken specimen shall be immediately laid on a smooth surface, the ruptured areas fitted
together as closely as possible with the two portions placed on a straight line, and the distance between
the bench marks measured to the nearest 1/32 inch. The length shall be recorded as L.
5. RESULTS
5.1 Calculation.
5.1.1 The tensile strength of the specimen shall be calculated as follows:
Tensile strength, p. s. i.= _4F_
š(D)
2
where:
F=the breaking force of the specimen, in pounds
D=minimum diameter of the specimen, inch
5.1.2 The elongation of the specimen shall be calculated as follows:
Elongation, percent = L-10 x 100
10
where:
L=the distance between bench marks on the specimen immediately after rupture, inches
5.2 Unless otherwise specified in the detail specification, three specimens from each inspection unit shall
be tested.
5.3 The tensile strength or elongation of the conductor or wire of the inspection unit shall be the average
of the results obtained from the specimens tested.
5.4 The tensile strength of the conductor or wire of the inspection unit shall be recorded to the nearest 10
pounds per square inch.
5.5 The elongation of the conductor or wire of the inspection unit shall be recorded to the nearest 0.5
percent.
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