PSI - Issue 57

Mathilde Renault et al. / Procedia Structural Integrity 57 (2024) 22–31 Mathilde RENAULT / Structural Integrity Procedia 00 (2019) 000 – 000

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5. Anisotropy effect on fatigue Crack initiation is identified using infrared image post-processing similar to that proposed by (Bercelli et al,2022& Carteron,2020). First, lock-in processing is applied to the film to retrieve maps of the temperature amplitude linked to thermoelastic coupling. Rigid body motion between each map is then corrected using a Euclidean algorithm. The initiation and propagation of cracks can be monitored by analyzing the evolution of the field of the temperature amplitude, as shown in Figure 5.

Figure 5 : Evolution of the temperature amplitude 1ℎ on rough surface during fatigue testing for = 130MPa However, the initial heterogeneous field due to the rough surface does not allow the cracks to be easily tracked, so differential measurement is performed by retrieving to each map the initial state, where no cracking occurred. In order to obtain those images, the following operation is done Δ 1ℎ ( , , ) = 1ℎ ( , , ) − 1ℎ ( , , 0) Eq 5 The results of this operation are shown in Figure6.

Figure6 : Differential measure of the temperature amplitude Δ 1ℎ for = 130MPa