Fatigue characterisation of structural steel by means of the small punch test: Development of a methodology

• A methodology for high cycle fatigue characterization of structural steels using SPT has been developed. • Fatigue characterization of S355 steel using rotating beam standard tests and the new SPT methodology. • Definition of iso -damage S PT -N curves for structural steels. • A parameter ( k SPT ) that correlate the fatigue limits from SPT and rotating beam test has been defined. Knowledge of the fatigue behaviour of materials is fundamental to the safe design of structures. Standardised tests are used for this purpose, but their application requires a considerable amount of material, which in many cases is not available. To overcome this problem, the use of miniature tests would be the optimal solution. This work analyses the application of the Small Punch Test (SPT) to characterise the fatigue behaviour of structural steels. To this end, an experimental methodology has been developed to analyse not only where SPT-fatigue damage initiates and how it propagates, but also its relationship with changes in specimen compliance. Based on this methodology, different S PT -N iso -damage curves and the SPT-fatigue limit have been obtained for two structural steels. By comparing these results with those obtained from rotating beam fatigue tests, a simple correlation has been proposed between the fatigue limits obtained from SPT and rotating beam fatigue tests.