Analysis of heat sources accompanying the fatigue of 2024 T3 aluminium alloys

This paper deals with the calorimetric analysis of fatigue mechanisms of an aluminium alloy. Local 1D and 2D expressions of the heat diffusion equation were used to separately estimate the coupling and dissipative sources accompanying the fatigue test. The image processing was based on local approximations of surface temperature fields provided by an IR camera. The set of approximation functions accounted for the spectral properties of the sought sources. The analysis of thermoelastic source distribution allowed us to point out the possible heterogeneous character of fatigue loading from the beginning of the test. We observed that the zones where thermoelastic source amplitudes were the highest were potential loci of fatigue crack onset. On the other hand, such fine results on the dissipative source distribution were hard to obtain because of low signal-to-noise ratios. Nevertheless, we observed that the global dissipated energy rates increased linearly with the loading frequency