This part of ISO 527 specifies the test conditions for determining the tensile properties of isotropic and orthotropic fibre-reinforced plastic composites. Typical reinforcement materials include glass fibers, carbon fibers, aramid fibers and other similar fibers. The properties typically desired from these materials include ultimate strength, strain at failure, modulus, and in some cases, Poisson's Ratio.
A suitable system for testing these types of materials would be an electromechanical testing machine with mechanical wedge grips or pneumatic side-acting grips. The choice of jaw faces may vary depending on sample type, but typically serrated faces are used. An extensometer is also required to accurately measure strain. Non-contacting extensometers, such as the Advanced Video Extensometer (AVE), have the resolution and accuracy to measure strain to failure for most composite materials. It is important to note, that because such little strain occurs within the initial linear elastic region of the stress-strain curve where modulus is measured, a clip-on extensometer is typically required in order to achieve the standard's extremely tight accuracy specification of approximately 1um.
If Poisson's Ratio is a desired property to be calculated, both an axial and a transverse extensometer are required. We find that our customers typically use a biaxial extensometer for this type of application.