ASTM D412 – Specimen Size

ASTM D412 is the most widely used standard for measuring the tensile properties of vulcanized (thermoset) rubber and thermoplastic elastomers. This is a general guide designed to help you understand the specimen sizes for an ASTM D412 tensile test and the various system configurations you can use to perform this test. Complete details are provided in the ASTM test manual.

ASTM D412 – SPECIMENS

Depending on the type of specimen, ASTM D412 provides two testing techniques. Please remember that the outcomes of the two testing techniques differ. Test method A uses specimens in the “dumbbell” or “dogbone” shape, whereas test method B uses specimens in the ring shape. Compared to test method B, test method A is more frequently employed. Dogbone specimens need to be die cut from a sheet or plaque that has been injection molded. Because it creates a delicate grain pattern in the material, the direction in which the sheet is extruded is crucial. For consistency, the longitudinal piece of each specimen should be sliced parallel to the grain.

ASTM D412 – SPECIMEN MEASUREMENT:

For ASTM D412 testing, there are two types of cut ring specimens and six types of dogbone specimens that can be used. The shape that is tested the most frequently is a die-cut C dogbone specimen, which needs to be 115 mm overall (the gauge length is 25 mm), 6 mm wide, and 3 mm thick. The specimen’s thickness must be measured three times, with the median measurement serving as the approved measurement.

ASTM D412 – SPECIMEN ALIGNMENT:

The specimens must be held perpendicular to the jaw faces during testing and not inclined at an angle. The specimens should be positioned consistently for each test since specimen misalignment can result in significant changes in test findings.

Common uses of ASTM D412

• Determines the tensile properties of vulcanized rubber and thermoplastic elastomers.