PSI - Issue 72

Sergio Arrieta et al. / Procedia Structural Integrity 72 (2025) 362–369

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observed between controlled laboratory conditions and actual component performance. The specific test matrix, detailed within WP3, is structured as follows:  WP3.3. Uniaxial Tests (solid and hollow cylindrical specimens): This WP focuses on the influence of surface finish, variable amplitude loading (Colin et al. (2010)), and simulated PWR environmental conditions. Testing commenced in November 2021, with preliminary results presented in Fig. 2. As of December 2024, 80 uniaxial tests have been completed.

Fig. 2. Uniaxial fatigue tests in air (at 300 ºC) and PWR environment.

 WP3.4. Features Testing: This WP will investigate the impact of loading conditions on fatigue life by employing specifically designed specimen geometries. Testing will be conducted in both air and PWR environments. Specimen designs will include, but are not limited to, membrane-type specimens, as described in Dhahri et al. (2018), cruciform specimens (Gill et al. (2021)), and notched solid specimens. Starting in 2024, 10 features tests have been completed. This initial phase of experimentation investigates the influence of variable amplitude loading and surface finish on the fatigue life of 316L stainless steel. Variable amplitude testing involves the superimposition of periodic overload cycles onto a baseline of constant amplitude cyclic loading, as illustrated in Fig. 3.

Fig. 3. Example of variable amplitude fatigue test (periodic overload).

The heterogeneity and complexity of the proposed testing regime necessitate a highly methodical approach, prioritizing the statistical relevance and analytical tractability of the variables. Furthermore, the utilization of non standardized methodologies requires careful consideration of data integration and comparability with results derived from standardized tests. To mitigate potential risks associated with these challenges, a preliminary assessment of each research topic was conducted, evaluating both its inherent difficulty and potential yield. Additionally, an Expert Panel