Applying infrared thermography to study the heating of 2024-T3 aluminium specimens under fatigue loading

The low cycle fatigue behaviour of the 2024-T3 aluminium alloy is examined in this paper in terms of both thermal measurements provided by an infrared camera and an energetic analysis performed with a suitable data processing. Oscillating variations of temperature are mainly due to the thermoelastic coupling. During the transient loading leading to the maximum stress value (higher than the yield stress of the material), sudden increases in temperature are observed. The heat sources produced by the material are assessed using the heat diffusion equation after an in-house filtering method. The mechanical dissipation attributed mainly to plastic strain is then estimated and the cumulative plastic damage is calculated by the temporal integral of it. Plastic damage fields are analysed for two geometries of specimens in order to underline structural effects and to study the initial damage state of the specimen before the steady-state cyclic loading.