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Flexural
Flexural properties
of plastics are obtained by placing a specimen on two supports
spaced 4 in. apart. A load is applied in the center at a
specified rate and the loading at failure (psi) is the flexural
strength. For materials which do not break, the flexural
property usually given is Flexural Stress at 5% strain.
In bending, a beam
is subject to both tensile and compressive stresses.
Because most
thermoplastics do not break in this test even after being
greatly deflected, the flexural strength cannot be calculated.
Instead, stress at 5% is calculated, i.e., the loading in
psi necessary to stretch the outer surface 5%. ASTM D-790.
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