7. Test Specimens
1 The specimens may be cut from sheets, plates, or
molded shapes, or may be molded to the desired finished
dimensions. The actual dimensions used in Section 4. , Calculation,
shall be measured in accordance with Test Methods
D 5947.
NOTE 3-Any necessar polishing of specimens shall be done only in
the lengthwise direction of the specimen.
2 Sheet Materials (Except Laminated Thermosetting Materials
and Certain Materials Used for Electrical Insulation
Including Vulcanized Fiber and Glass Bonded Mica):
1 Materials mm Wl6 in. ) or Greater in Thickness-
For flatwise tests, the depth of the specimen shal be the
thickness of the material. For edgewise tests, the width of the
specimen shall be the thckness of the sheet, and the depth shal
not exceed the width (see Notes 4 and 5). For all tests, the
support span shal be 16 (tolerance :! 1) times the depth of the
beam. Specimen width shall not exceed one four of the
support span for specimens greater than 3.2 mm (18 in.) in
depth. Specimens 3.2 mm or less in depth shall be 12.7 mm (12
in.) in width. The specimen shall be long enough to allow for
overhanging on each end of at least 10 % of the support span,
but in no case less than 6.4 mm (1/4 in.) on each end. Overhang
shall be sufcient to prevent the specimen from slipping
though the supports.
NOTE 4-Whenever possible, the original surace of the sheet shall be
unaltered. However, where testing machine limitations make it impossible
to follow the above criterion on the unaltered sheet, one or both surfaces
shall be machined to provide the desired dimensions, and the location of
the specimens with reference to the total depth shall be noted. The value
obtaned on specimens with machined surfaces may differ from those
obtained on specimens with original suraces. Consequently, any specifications
for flexural propertes on thcker sheets must state whether the
original suraces are to be retaned or not. When only one surace was
machined, it must be stated whether the machined surace was on the
tension or compression side of the beam.
NOTE 5-Edgewise tests are not applicable for sheets that are so thn
that specimens meeting these requiements canot be cut. If specimen
depth exceeds the width, bucklg may occur.
2 Materials Less than mm WI6 in.) in Thickness-
The specimen shal be 50.8 mm (2 in.) long by 12.7 mm (12 in.
wide, tested flatwise on a 25.4-mm (I-in.) support span.
NOTE 6-Use of the formulas for simple beams cited in these test
methods for calculating results presumes that beam width is small in
comparson with the support span. Therefore, the formulas do not apply
rigorously to these dimensions.
NOTE 7-Where machine sensitivity is such that specimens of these
dimensions canot be measured, wider specimens or shorter support
spans, or both, may be used, provided the support span-to-depth ratio is at
least 14 to 1. All diensions must be stated in the report (see also Note 6).
3 Laminated Thermosetting Materials and Sheet and
Plate Materials Used for Electrical Insulation, Including
Vulcanized Fiber and Glass-Bonded Mica-For paper-base
and fabric-base grades over 25.4 mm (1 in.) in nominal
thckness, the specimens shall be machined on both suraces to
a depth of 25.4 mm. For glass-base and nylon-base grades
specimens over 12.7 mm (12 in.) in nominal depth shal be
machined on both suraces to a depth of 12.7 mm. The support
span-to-depth ratio shall be chosen such that failures occur in