ASTM D5379 | Composites | Shear Testing
ASTM D5379 is a testing standard designed to measure the shear properties of composite materials. This test procedure introduces the compressive force into the specimen through shear at grip interfaces.
This test method measures the shear stress/strain, the ultimate strength and the ultimate strain, as well as the shear chord modulus of elasticity. The test utilizes a standard universal testing machine and a specially-designed fixture with wedge grip interfaces that clamp one half of the test specimen across its width and support it on its back face as described in the specification. The lower fixture should be mounted on a base plate that supports a linear bearing shaft. The upper fixture should contain a linear bearing which mounts over the shaft on the base.
A minimum of two shear strain gauges with a thin active gauge section that spans the length of the test section between notch roots is recommended to complete the test procedure. Before conducting ASTM D5379, it is important to read the entire specification in the relevant ASTM publication.
ASTM D5379 | Composites | Shear Testing
- Prepare v-notched beams as described in the standard.
- Connect strain gauges to the controller and attach them at +45˚ and -45˚ to the loading axis of the specimen. Zero the force reading.
- Place the specimen loosely into the fixture making sure the notch alignment tool is pulled up into the notch. Lightly tighten the left-hand-side-jaw, and then lightly tighten the right-hand-side jaw. Make sure that the specimen is centered in the fixture and that it is contacting both upper and lower grip jaws on both sides while still being supported on the back side.
- Apply the force at a constant strain rate until failure. Record force versus strain (or position). When the specimen breaks, record the maximum force, the force at failure and the strain as near as possible to the failure. If ultimate strain doesn’t occur within 5% engineering shear strain, truncate the data to this value.
- Shear Stress/Ultimate Strength
- Shear Strain/Ultimate Strain
- Shear Modulus of Elasticity
- Shear Chord Modulus of Elasticity
- Offset Shear Strength
ASTM D5379 | Composites | Shear Testing
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