PSI - Issue 37

Pedro J. Sousa et al. / Procedia Structural Integrity 37 (2022) 730–737 Sousa et al. / Structural Integrity Procedia 00 (2019) 000 – 000

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Regarding ESPI, this machine is already being used with MT specimens, Fig. 8b, where the behavior of the specimen, when subjected to static forces, is analyzed, starting from 1750 N as the reference state, up to 2000 N as the deformed state. Only the Y-direction-sensitive setup was used, and it was possible to obtain good quality phase measurements, as well as the respective displacement field, both shown in Fig. 9.

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Fig. 9. Example of the application of the developed machine to ESPI measurements to an MT specimen subjected to a load from 1750 N (reference situation) to 2000 N (deformed situation): (a) phase measurement; (b) displacement measurement.

In general, a custom portable testing machine was developed for use with interferometric optical methods, in this case mainly Electronic Speckle Pattern Interferometry. It fulfills the design requirements reaching loads of 20 kN and speeds of 240 mm/min, while enabling the use of ESPI with promising results, showing good quality phase maps and displacement fields. Additionally, the machine is already operational, being used in multiple projects and with different specimens. Acknowledgements The authors sincerely acknowledge the funding received from Ministério da Educação e Ciência, Fundação para a Ciência e a Tecnologia (Portugal), under grant PTDC/EME-EME/29339/2017. References Carre, P., 1966. Installation et utilisation du comparateur photoelectrique et interferentiel du Bureau International des Poids et Mesures. Metrologia 2, 13. Creath, K., 1985. Phase-shifting speckle interferometry. Appl. Opt. 24, 3053 – 3058. Grediac, M., Hild, F., 2012. Full-Field Measurements and Identification in Solid Mechanics. Wiley-ISTE, London. Kemao, Q., 2004. Windowed Fourier transform for fringe pattern analysis. Appl. Opt. 43, 2695. Kemao, Q., 2007. Two-dimensional windowed Fourier transform for fringe pattern analysis: Principles, applications and implementations. Opt. Lasers Eng. 45, 304 – 317. Kemao, Q., Gao, W., Wang, H., 2008. Windowed Fourier-filtered and quality-guided phase-unwrapping algorithm. Appl. Opt. 47, 5420. Odintsev, I.N., 2021. Investigation of elastic properties of composite materials with use of ESPI. Mater. Today Proc. 38, 1919 – 1924. Rickert, T.J., Suominen, L., 2017. Residual stress measurement by ESPI hole drilling and XRD – a comparison of the methods using measurements on shot-peened titanium alloys 74 – 79. Sousa, P.J., Carneiro, F., Ramos, N.V., Barros, F., Vaz, M.A.P., Tavares, P.J., Moreira, P.M.G.P., 2019. Application of 3D electronic speckle pattern interferometry for the analysis of thermal response in printed circuit boards. Procedia Struct. Integr. 17, 835 – 842. Yang, L., Xie, X., Zhu, L., Wu, S., Wang, Y., 2014. Review of electronic speckle pattern interferometry (ESPI) for three dimensional displacement measurement. Chinese J. Mech. Eng. 27, 1 – 13.