Fatigue damage is one of the main failure mechanisms of structures. In the present work Electrical Resistance Changes (ERC) were measured during fatigue tests on notched carbon steel specimens. ERC measurements were performed by monitoring the change in electrical resistance in real-time without interrupting the test at various pre-selected time intervals. The temperature of the specimens was also on-line monitored during the test in order to deduce its effect on the electrical resistance. The comparison of the resistance data measured at initial and different phases of fatigue tests showed the existence of temporal variations associated to fatigue damage: in particular the resistance first decreases, in the initial stages of loading, and subsequently, starting approximately from half-life presents an increase with the number of load cycles due to the internal micro-damage’s accumulation. In the final stages of the fatigue test, prior the final fracture, it increases rapidly, in the propagation phase of the crack. In conclusion, the applied experimental method proved to be valid for studying the evolution of damage and to predict and evaluate fatigue life effectively.
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