ASTM D6272 is a test method used to determine the flexural properties of unreinforced and reinforced plastics. These materials include high modulus
composites and electrical insulation materials. This flexure test requires a 4-point fixture where the bottom span is set by a span-to-depth ratio of 16:1
and the top is set at two points equidistant from the centerline. A 4-point bend fixture fully complies with the fixture requirements.
Two test procedures, Procedure A and B, are used, depending on the material properties. Procedure A is used for brittle materials that fracture at low deflections.
Procedure B is used for flexible, more ductile materials that experience large deflections. The specimen is deflected until fracture or 5% strain is reached, whichever
occurs first. To accurately measure the deflection, a calibrated device that meets the ASTM E83 Class C standard for deflection measurement is required.
