Shear strength testing for plastics, by ASTM D-732.

Intertek provides shear strength testing using the ASTM D732 punch tool technique.

Shear strength by punch tool ASTM D-732 scope:
Shear strength testing is used to determine the load at which a plastic or film will yield when sheared between two metal edges. Shear strength results are important to designers of film and sheet products that tend to be subjected to shear loads, or in applications where applied crushing loads are a risk.

ASTM D-732 test procedure:
The test is performed by clamping a test sample attached to a 1-inch punch between two metal fixtures. A male punch is then forced through the hole in the metal fixture causing shear along the edge of the hole. A universal testing machine is used to push the punch until shearing of the specimen occurs.

Specimen size:
The specimens are usually 2 inch diameter discs or 2 inch squared plates and thickness ranging between 0.05 and 0.5 inch. A 7/16th inch hole is drilled through the center of the specimen to mount it in the fixture.

The results are expressed as shear strength and are given in the units of MPa or psi. The shear strength is calculated by dividing the force required to shear the specimen by the area of the sheared edge. The area of the sheared edge is equal to the circumference of the punch multiplied by the thickness of the specimen.


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