ASTM D3039 describes the standard method for
tensile testing polymer matrix composites. It covers test methods for a wide range of specimen dimensions as well as many different testing configurations. In this application we tested carbon fiber specimens. The specimens were prepared with tabbed ends that allowed for a secure grip on the specimen and ensured that breaks occured within the gauge length and not in the jaw face. This testing was preformed for a customer that desired results from their specimens at both high (85° C) and low (-60° C) temperatures.
For this test, we used a
5585H floor model system because it is designed for tensile testing applications. To test the specimens at the required temperatures, we used an
environmental chamber with a range from -100° C to 350° C. This chamber allowed us to run tests at 85° C using the internal heating coils and then at -60° C by piping in liquid nitrogen. Before starting the test we placed the specimen in
30 kN mechanical wedge grips, attached our
clip-on extensometer, and waited for the chamber to reach the set temperature. When testing far below or above ambient temperatures, polymer composites will often expand or contract, putting the specimen in tension or compression as the temperature changes. The 5500 Series frames used with
Bluehill 2 Software come with a
specimen protect feature that allows you to set a load threshold that won't be exceeded until the test is started. Additionally, we used the optional
specimen alignment device to ensure optimal alignment of the specimen in the jaw faces, since offset loading can greatly effect tests results.
We successfully tested carbon fiber specimens using the environmental chamber to hold our desired temperature. The results we included using Bluehill 2 Software are
tensile strength,
strain at
break, and
Young's modulus. Other results included in ASTM D3039 are
Poisson's ratio and transition strain.
Due to the complexities and enormity of ASTM D3039, we recommend that you review the standard to fully understand its requirements.