ASTM D7137 | Composites | Compression Testing
ASTM D7137 is a testing standard designed to measure the compression residual strength properties of multidirectional polymer matrix composite laminated plates. Susceptibility to damage from concentrated out-of-plane forces is one of the major design concerns of advanced composite laminates. Damage resistance and damage tolerance properties that are derived from this test are useful for product development and material selection.
This test method measures the ultimate compressive residual strength and the effective modulus. A uniaxial compression test is performed using a symmetric laminated sample, which has been damaged and inspected prior to the test, typically per testing via ASTM D6264 or ASTM D7136. The damage is caused by quasi-static indentation or drop-weight impact. Compressive force is applied on the specimen until failure. Applied force, crosshead displacement, and strain data are recorded, continuously. Before conducting ASTM D7137, it is important to read the entire specification in the relevant ASTM publication.
ASTM D7137 | Composites | Compression Testing
- Prepare at least five test specimens as described in the standard. Make sure to follow the instructions for sample preparation and for sample impact in the standard.
- Mount the specimen on the support fixture. Place the specimen and the fixture assembly between flat platens of the testing machine and center it.
- To ensure all loading surfaces are in contact, apply a compressive load. Decrease the compressive load and tare and zero all instrumentation.
- To calculate the percent bending, torque the fixture screws attaching the side and the slide plates. Then apply compressive load until 10% of the anticipated ultimate force is achieved. Decrease the compressive load. Check strain gauge output from opposite faces of the specimen to determine how much specimen bending occurred. Calculate the percent bending at maximum applied force.
- Apply the compressive force at the speed specified in the standard. To determine the effective compression modulus, measure the laminate stress at two specified strain levels, 1000 and 3000 microstrain as described in the method. The applied force at 1000 and 3000 microstrain is an estimate of the average strain.
- Measure and record the force versus displacement and force versus strain (if performed) data, continuously, of minimum 100 data points.
- Ultimate Compressive Residual Strength
- Effective Modulus
ASTM D7137 | Composites | Compression Testing
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