PSI - Issue 57

SEVEDE Théo et al. / Procedia Structural Integrity 57 (2024) 335–342 SEVEDE Théo/ Structural Integrity Procedia 00 (2019) 000 – 000

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the axial length of the sample. The maximum value of the thermal source is registered at the center of the sample when it is equalto zero at the extremities. In addition, its maximum intensity increases with increasing the stress amplitude. furthermore, the algebraic value of the thermal source remains positive and meets the thermodynamics’ laws. 4. Conclusion This study has enabled to set up a methodology to assess the thermal source term through a specimen subjected to a heterogeneous stress amplitude. Unlike the historically assumed 0D approach in homogeneous loading cases, the conventionalself-heating methodology does not allow to correctly identify the thermal source term in heterogeneous configuration. The proposed methodology in this study is based on identifying the temperature field in the form of a second-degree polynomial coupled to a Fourier series basis and as function of the specimen axial position. Writing the 1D heat equation gives a direct relationship between the thermal source term and the temperature field, enabling to calculate it. The proposed method enables to identify the thermal source term field along the specimen with a high accuracy. This thermal source will be used as input data for the multiscale probabilistic model to determine the fatigue curves of the material. 5. References [1.] Bathias, Claude. "There is not infinite fatigue life in metallic materials." Fatigue & Fracture of Engineering Materials and Structures , 1999: 559-565. [2.] Behnaz Amini, Younes Demmouche, Mahmoud Barati, Guillaume Helbert, Shabnam Arbab Chirani, Sylvain Calloch,. "Self-heating of metastable 304L austenitic stainless steel under cyclic loading: Influence of initial martensite volume fraction, testing temperature and pre-strain." Mechanics of Materials , 2020: 103-596. [3.] Cédric Doudard, Sylvain Calloch, François Hild, Philippe Cugy, André Galtier,. "Identification of the scatter in high cycle fatigue from temperature measurements." Comptes Rendus Mécanique , 2004: 795-801. [4.] Cédric Doudard, Sylvain Calloch, François Hild, Stéphane Roux,. "Identification of heat source fields from infrared thermography: Determination of ‘self - heating’ in a dual -phase steel by using a dog bone sample." Mechanics of Materials , 2010: 55-62. [5.] Claude Bathias. "Piezoelectric fatigue testing machines and devices." International Journal of Fatigue , 2005: 1438 – 1445. [6.] Corentin Guellec, Cédric Doudard, Bruno Levieil, Ludovic Jian, Anthony Ezanno, Sylvain Calloch,. "Parametric method for the assessment of fatigue damage for marine shaft lines,." Marine Structures , 2023: 0951-8339. [7.] N. Ranc, A. Messager, A. Junet, T. Palin-Luc, J.Y. Buffière, N. Saintier, M. Elmay, L. Mancini, A. King, Y. Nadot,. "Internal fatigue crack monitoring during ultrasonic fatigue test using temperature measurements and tomography." Mechanics of Materials Volume 174 (2022): 0167-6636. [8.] Perez Mora, R. Study of the fatigue strength in the gigacycle regime of metallic alloys used in aeronautics and offshore industries. Mechanics of materials. Arts et Métiers ParisTech, 2010. [9.] Rémi Munier, Cédric Doudard, Sylvain Calloch, Bastien Weber,. "Determination of high cycle fatigue properties of a wide range of steel sheet grades from self-heating measurements." International Journal of Fatigue , 2014: 46-61.