PSI - Issue 42

A. Sulamanidze et al. / Procedia Structural Integrity 42 (2022) 412–419 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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The strain-controlled TMF standards highlights the significance of dynamic temperature effects on material fatigue behaviour. A homogeneous temperature distribution is crucial for the replication of TMF in a test laboratory. All of the standards published state the importance of achieving a maximum temperature gradient across the specimen ( ± 5 °C or ± 1%ΔT circumferentially at the gauge location and ± 10°C or ± 2%ΔT axially. In accordance of the requirements for reduced cycle time, as a rule, an induction coil system (ICS) is adopted for the heating cycle and air amplifiers are utilised for cooling to achieve high temperature rates. Usually temperatures are measured and controlled using thermocouples, infra-red pyrometry or more recently thermal imaging cameras. In order to validate the proposed multi-physics algorithm, the temperatures measured by infra-red camera InfraTec ТХ VarioCAM on the lateral surface of SENT specimen were compared to that computed by FEM in the section located at the centre of the gauge length. The measured temperature variation is displayed in Fig. 4a for start (400°C, point 2) and end (650°C, point 3) of heating. Figures 4b and 4c give the comparison of the numerical and experimental data for the same temperature conditions and it can be seen that there is a good agreement between them.

Fig. 4. (a) Infra-red thermography temperature measurements and comparison with FEM (b + 400°C), (c + 650°C).

Fig. 5. 3D-temperature distributions in 5 th IP thermo-mechanical cycle.