Fatigue behaviour of discontinuous carbon-fibre reinforced specimens and structural parts

Discontinuous fibre reinforced polymers are increasingly used for structural components in automotive applications. In this paper, specimens made from a carbon-fibre sheet moulding compound are tested in constant amplitude fully reversed cyclic fatigue loading. The obtained fatigue lifetime curves are compared against component fatigue test results. In addition, the evolution of modulus in the specimen is compared to the structural stiffness in the component. A power law is used to describe both, degradations of specimen modulus and component stiffness. The exponent of the power law is proportional to the load amplitude, potentially indicating the existence of a fatigue limit.