Establishing Gauge Length
The gauge length used for a tensile test refers to the
original length of the specimen or the initial distance be-
tween the grips. Whereas for a compression test, it refers
to the original height of the specimen, assuming the an-
vil and compression table are both initially in contact
with the specimen.
Establishing gauge length is one of the most important
decisions to be made when performing tension tests.
Gauge length is used as a basis for calculating percent
elongation and in determining specimen strain rate;
hence, it can seriously affect the test results.
Sometimes the choice of gauge length is dictated by the
available length of the material, although commonly
used gauge lengths for paper, plastic film, wire, cord and
yarns are from 4 to 10 inches (100 to 250 mm). In gen-
eral: establish the longest possible gauge length, consis-
tent with the capacity of the testing instrument, in order
to increase the sensitivity and accuracy of the elongation
measurement.
Appendix A
Test Planning
Establishing Gauge Length
A-7
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