PSI - Issue 68

J.C. Gomez-Mancilla et al. / Procedia Structural Integrity 68 (2025) 1208–1215 Gomez-Mancilla J / Structural Integrity Procedia 00 (2025) 000–000 St

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6.2 Manufacturing defects : External and internal pore corrosion was detected, associated with manufacturing defects. This pore is located 430 µm from the surface, with an approximate diameter of 150 µm. No significant cracks are observed connecting this pore with the surrounding microcracks, but it could act as a stress concentrator. 7. Conclusions Nowadays, industries and markets demanding quality control of engineering products require the characterization of their performance by various international standards, including Very High Cycle Fatigue (VHCF) analysis and characterization. Such an international testing standard must render properties of fundamental importance that are not limited to the number of endured load cycles but also where the probe’s Damage Onset starts, which can be identified and characterized. This work proposes three novel criteria based on a modified test set-up proposal, adding another synchronous monitoring axis to the existing axial (Ch1), an orthogonal bending vibration at the probe’s tip (Ch2). The first criterion uses the axial response data, and its results coincide with the existing Nonlinear Acoustic Emission NAE criterion. The results from these two criteria are interesting given the relatively significant difference in the frequency spectra, between 19.5 and 105 kHz, vs. the NAE typically operating in MegaHertz. The second damage onset criterion relies on measuring the bending frequency-split phenomena, BFSI indexes proposed by Gomez-Mancilla (2024), obtained from the bending monitoring axis. In addition, due to stiffness loss, the BFSI damage indexes can be used to estimate a crack-like gravity. The third criterion relies on observing the amplitude and trends of the bending amplitude, which is much more sensible than the currently monitored axial vibration, refer to Fig. 6. To validate, criteria are applied to a real test using sophisticated VHCF equipment, yielding successful results. Finally, an X-ray, XCT, (2024) scan. Computerized tomography using GE Phoenix v|tome|x m is realized on the AISI 302 steel probe. Detection of intergranular microcracks extending in a zigzag pattern suggests a significant advance in material degradation due to fatigue. The results are successful and coherent with the three proposed onset damage criteria, primarily as PSB, and with this work's conclusions. Acknowledgements The author wishes to thank the Sistema Nacional de Investigadores S.N.I. CONACyT ; to Prof. Alfonso Beltrán Fdez, at SEPI-ESIME-Zac. Special thanks to Prof. Nicholas Ranc for providing me with the experimental data here presented that I analyzed; I am grateful with the PIMM Laboratory for the sabbatical year, 2021-2022, spent at the École Nationale Supérieur Arts et Metiers, ENSAM, Paris, France. References Amziane M., Dubé J.F. (2008), Global RC structural damage index based on the assessment of local material damage, J. Adv. Concr. Technol. , vol. 6, no. 3, 2008, doi: 10.3151/jact.6.459. Bathias Claude and Paris Paul C., (2006). Gigacycle fatigue in Mechanical Practice”, Mechanical Engineering book series, ISBN: 0-8247-2313-9, Marcel Dekker, NY, Ed., 2006. Gomez-Mancilla J., (2014), Bending Frequency-Splitted Indexes (BFSI) , a nonlinear method & damage characterization for 1-D vibration-based SHM, ECF24 , submitted for review to Procedia Structural Integrity, Aug. 26-30, 2024, Zagreb. Jacquemain V., Ranc N., Cheuleu C., Michel V., Favier V., Castelnau O., Vinci D., Thiaudiere D., Mocuta C., (2021). Estimation of stress in specimens loaded with ultrasonic fatigue machines, International Journal of Fatigue, vol 153, August 2021 Khan M, Islam T, Nagao T, Kondo Y, Teramoto K, Hattori N. (2015). Monitoring the fatigue damage in ductile cast iron by AE technique. International Journal of COMADEM. 2015; 18 :27-33 Kiser S., Guskov M., Ranc N., (2021). Harmonic Balance Framework For Ultrasonic Fatigue Vibration, Eight International Very High Cycle Fatigue Conference (VHCF8), July 6 th , 2021. Machorro-Lopez M., Adams D.E., Gomez-Mancilla J.C., Gul K.A., (2009). "Identification of damaged shafts using active sensing-Simulation and experimentation," J. Sound Vib. , 2009, doi: 10.1016/j.jsv.2009.06.025 Messager A., Junet A. et al , (2020). In situ synchrotron ultrasonic fatigue testing device for 3D characterization of internal crack initiation and growth, Fatigue Fract Eng Mater Struct . 2020;43. Mostofapour A, Davoodi S. A (2017). Method for acoustic source location in plate-type structure. Mechanical Systems and Signal Processing. 2017; 93 :92-103