Heat Source Reconstruction Applied to Fatigue Characterization Under Varying Stress Amplitude

Fatigue damage is associated with heat release leading to material self-heating. The present study deals with the measurement of mechanical dissipation from temperature measurements by infrared (IR) thermography during a fatigue test with varying stress amplitude. The experiment was performed in two steps on an additively manufactured steel specimen. First, specific acquisition conditions of the thermal response were used to remove the cyclic fluctuation due to thermoelastic coupling. Second, heat source reconstruction was applied to evaluate the calorific origin of the self-heating during the test. A simplified version of the heat diffusion equation was used assuming a uniform distribution of mechanical dissipation within the specimen. The relationship between stress amplitude and mechanical dissipation was identified without the need for a steady thermal regime at constant load amplitude.