8.6 Load-Deflection Curves:
8.6.1 Load-deflection curves shall be recorded to or beyond
the maximum load for all static bending tests. The curves shall
be continued to a 6 in. (150 mm) deflection, or until the
specimen fails to support a load of 200 lbf (890 N) for primary
method specimens and to a 3 in. (76 mm) deflection or until the
specimen fails to support a load of 50 lbf (220 N) for secondary
method specimens.
8.6.2 Deflections of the neutral plane at the center of the
length shall be taken with respect to points in the neutral plane
above the supports. Alternatively, deflection may be taken
relative to the tension surface at midspan. However, take care
to ensure that vertical displacements which may occur at the
reactions are accounted for.
8.6.3 Within the proportional limit, deflection readings shall
be taken to 0.001 in. (0.02 mm). After the proportional limit is
reached, less refinement is necessary in observing deflections,
but it is convenient to read them by means of the dial gage