This paper combines the infrared thermography and the computed laminography techniques to better understand the mechanisms of damage under fatigue for a short fibre-reinforced thermoplastic material. Depending on the experimental technique used, the measurement implies a “homogenization” of the values deduced over a prescribed volume. The real volume contributing to the thermal fields and thus the dissipated energy evaluated from thermography cannot be easily determined. The laminography technique provides precious insights for the determination of the dissipation fields, by providing a clearer view of the in-depth notch front profile as well as the local fibre orientation and by giving an idea of the volume change induced by porosity. In turn, the latter may affect the physical (thermal) constants used in the determination of the dissipated energy.