Compressive properties of polymer matrix composite laminates using a combined loading compression (CLC) test fixture, by ASTM D6641

Intertek composites and polymers laboratories provide ASTM D6641 testing for composite laminates.

Compressive Properties ASTM D6641 Scope:
This test method determines compressive properties of polymer composite materials by applying combined end-loading and shear-loading using a combined loading compression (CLC) fixture. ASTM D6641 is designed for polymer matrix composite laminates which contain at least one 0˚ ply, but other materials can also be tested. The test fixture is designed to provide a combined loading to the unsupported center 12 mm (0.5 inch) gauge length of the specimen.

In comparison, other ASTM test methods outline only shear-loading such as ASTM D3410 or only end-loading such as ASTM D695.

Alternatively perform ASTM D6641 modified using the Hydraulic Composites Test Fixture (HCCF) for improved reproducibility.

ASTM D-6641 Test Procedure:
The test specimen is inserted into the two halves of the test fixture so that the ends of the specimen are flush with the top and bottom of the test fixture, and the bolts in the fixture are tightened to a specified torque to capture the test specimen. The fixture is placed between the platens of a Universal Testing Machine, and if a strain measuring device is being used, it is attached to the specimen. The specimen is compressed to failure.


  • Laminate compressive strength (maximum load / (specimen width x specimen thickness)
  • Laminate compressive modulus (chord modulus from 0.1% to 0.3% strain)
  • Compressive Poisson’s Ratio by chord method (calculated from 0.1% to 0.3% strain)

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