ASTM D5379 is a testing standard designed to measure the shear properties of composite materials. This testing program introduces compressive force into the specimen through shear at the fixture interface.

This testing method measures shear stress/strain, ultimate strength and strain, as well as shear string elastic modulus. This test uses a standard universal testing machine and a specially designed fixture with a wedge-shaped fixture interface, which clamps half of the specimen across its width and supports it on its back according to the specifications. The lower fixture should be installed on the bottom plate supporting the linear bearing shaft. The upper fixture should include a linear bearing installed on the shaft of the base.

It is recommended to use at least two shear strain gauges, with the thin effective strain gauge section spanning the length of the test section between the notch roots, to complete the testing procedure. Before implementing ASTM D5379, please be sure to read the complete specifications in the relevant ASTM publications.

Test procedure:

Prepare V-shaped notched beams according to the instructions in the standard.

Connect the strain gauges to the controller and connect them to the loading axis of the specimen at speeds of 45 ° and -45 °. Reset the force reading to zero.

Loosely place the sample into the fixture, ensuring that the notch is aligned and the tool is pulled into the notch. Gently tighten the left lower jaw, then gently tighten the right lower jaw. Ensure that the specimen is centered in the fixture and in contact with the upper and lower jaws on both sides, while still being supported on the back.

Apply force at a constant strain rate until failure occurs. Record the relationship between force and strain (or position). When the specimen fractures, record the maximum force, the force at failure, and the strain as close as possible to failure. If the ultimate strain does not occur within the 5% engineering shear strain range, please truncate the data to this value.