ASTM D7291 | Composites | Tension Testing
ASTM D7291 is a testing standard designed to measure the through-thickness flatwise tensions strength and elastic modulus of polymer matrix composites. A composite specimen in the shape of either a straight-sided cylindrical disk or a reduced gauge section cylindrical spool is adhesively bonded to cylindrical metal end tabs. The bonded assembly is loaded under flatwise tensile force applied normal to the plane of the specimen until failure. Please note that, for this test to be considered valid, the failure has to occur entirely within the composite laminate.
ASTM D7291 test procedure requires a universal testing machine and a fixture consisting of three different parts that is designed according to the requirements of the standard. Strain gauges may also be used to measure the Modulus of Elasticity. Before conducting ASTM D7291, it is important to read the entire specification in the relevant ASTM publication.
ASTM D7291 | Composites | Tension Testing
Note that there are slight variations depending on the type of sample selected.
- Prepare the test specimen as described in the standard. Measure the specimen diameter at three locations around the circumference. Calculate and record the average diameter.
- Bond the end tabs to the specimen and mount it into the ASTM D7291 fixture. Make sure the long axis of the specimen is aligned and the end tab assembly is aligned with the test direction.
- Apply the strain gauges to the specimen to measure the Modulus.
- Apply a tensile force at a constant crosshead displacement rate as specified in the standard. Measure and record the force versus crosshead displacement data. If strain gauges are used, record the strain data. For specimens that are to be tested to failure, record the maximum force and the displacement (or strain) at the moment of failure.
- Ultimate Flatwise Through-Thickness Tensile Strength
- Through-Thickness Modulus of Elasticity
ASTM D7291 | Composites | Tension Testing
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