ASTM D7078 | Composites | Shear Testing
ASTM D7078 is a test method used to study the shear properties of a composite material. While the test fixture and set up for this test may look a little complicated, the mechanics and calculations of the test are straightforward. The specialized fixture allows the user to apply very high shear forces due to loads being applied through the specimen faces as opposed to edges. The V-notched specimen shape provides a consistent and localized failure in the gauge area.
Before conducting ASTM D7078, it is important to read the entire specification in the relevant ASTM publication.
ASTM D7078 | Composites | Shear Testing
- Prepare and condition the test specimens according to the geometries and guidance described in the test standard. ASTM D7078 provides recommendations regarding fiber orientations of the specimen and how they will affect test results.
- Measure and record the specimen’s width and thickness at the notched location.
- Insert the test specimen in the grips according to the procedure described in the test standard. Spacers are used to assist in centering the specimen in the grips, which is essential for accurate results.
- Ensure the bonded strain gages are properly mounted to the specimen and zeroed. Tighten the clamping bolts to the specified torque.
- Mount the test fixture in the test machine.
- Apply load to the specimen at the specified rate prescribed by the test standard.
- Continue the test until failure.
Calculations:
- Ultimate Shear Strength
- Ultimate Shear Strain
- Modulus of Elasticity
ASTM D7078 | Composites | Shear Testing
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