Testing the strength and stiffness of polymer matrix composites

Abstract: The directional nature of fibre reinforced polymer matrix composites makes them a more formidable proposition than do isotropic materials such as metals and plastics when attempting to measure their true mechanical properties. It can be extremely difficult to ensure that a pure and uniform stress state is imposed on a significant volume of the material in order to extract the desired property data. If that is to be achieved, great care is required in the design of specimens and loading arrangements. Whatever the idealised designs for specimen and loading jig turn out to be, they still need to be transferred into reality, which means that equal care is required in creating both. Assuming this can be done satisfactorily, there are test method standards available that define how the test should be carried out. Some are better than others in achieving what they set out to do. This chapter attempts to guide the test practitioner through what can be something of a minefield.