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Determining the fatigue behaviour of metallic materials using standardised testing methods is costly and time-consuming. Therefore, several methods have been proposed to shorten the testing time and improve the fatigue optimisation of materials and components. This work presents a new fatigue testing method based on fatigue damage monitoring that allows determining the fatigue resistance in a short time and with few specimens. The presented method, named as the stiffness method, monitors the inelastic strains as an indicator of fatigue damage evolution. Strain measurements were carried out by digital image correlation techniques and showed to effectively follow damage evolution during fatigue tests. Results are convincing and more evident to obtain and discuss than other monitoring techniques, like temperature dissipation. In addition, the method overcomes the main limitations of the existing fast testing methods by avoiding the utilisation of complex apparatus, like infrared cameras or acoustic emission sensors. The approach has been validated in ten different metallic materials, as titanium and aluminium alloys, carbon steels, and stainless steels. The estimated fatigue limit was compared with values obtained following standardised tests, showing excellent agreement. Results allow pointing out the stiffness method as an efficient and effective tool for rapidly determining the fatigue behaviour of metallic materials. Validerad;2023;Nivå 2;2023-06-26 (hanlid);Funder: Fatigue4Light project and the Ministerio de Ciencia e Innovación (PID2019-106631GBC41)

In this work, a numerical procedure to obtain the fatigue performance of composite laminates is proposed. The formulation used is based on the Serial/Parallel Mixing Theory (SP-RoM) and a fatigue damage model. The SP-RoM acts as a constitutive law manager, obtaining the mechanical performance of the composite by solving the behaviour of each constituent material. The fatigue damage model modifies the constitutive performance of the composite constituents in order to consider the degradation of their mechanical properties due to cyclic loading. The proposed formulation is validated for two composite systems, a carbon/epoxy system and a glass/polyester system. In addition, different composite configurations are numerically evaluated and compared with experimental data, in order to prove the capabilities of the formulation. All results prove that the numerical procedure develop is an excellent tool for obtaining the fatigue life and failure mechanisms of composite materials.