PSI - Issue 37

Jürgen Bär et al. / Procedia Structural Integrity 37 (2022) 336–343 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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• The calculation of quotients allows the easy detection of crack initiation by using the separation of the curves in case of asymmetric and steps for symmetric cracks. • The inclination of a crack front leads to differences in the potential quotients. • The curvature of a crack front is difficult to describe due to the different sensitivity of the potential probe on the narrow and on the flat side of the specimen. • For a quantitative description of the crack length and the inclination and curvature of the crack front detailed FEM calculations and additional experiments are needed. The use of multiple potential drop measurement appears to be a promising method and will be investigated in further experiments. References Bär, J.; Volpp, T.; 2001 Vollautomatische Experimente zur Ermüdungsrissausbreitung. Materialprüfung 43, 242-247; DOI: 10.1515/mt-2001 430610. Bär, J.; Tiedemann, D.; 2017. Experimental investigation of short crack growth at notches in 7475-T761. Procedia Structural Integrity 5, 793–800; DOI:10.1016/j.prostr.2017.07.171. Bär, J.; 2020. Crack Detection and Crack Length Measurement with the DC Potential Drop Method–Possibilities, Challenges and New Developments, Appl. Sci. 10(23), 8559; DOI: 10.3390/app10238559 Bauschke, H.-M.; Schwalbe, K.-H.; 1985. Measurement of the depth of surface cracks using the Direct Current Potential Drop Method, Z. Werkstofftechnik 16, 156–165; DOI:10.1002/mawe.19850160504. Campagnolo, A.; Bär, J.; Meneghetti, G.; 2019. Analysis of Crack Geometry and Location in Notched Bars by Means of a Three-Probe Potential Drop Technique, International Journal of Fatigue 124, 167-187; DOI: 10.1016/j.ijfatigue.2019.02.045. Černý, I., 2004. The use of DCPD method for measurement of grow th of cracks in large components at normal and elevated temperatures. Engineering Fracture Mechanics 71, 837–848; DOI:10.1016/S0013-7944(03)00012-2. Chretien, G.; Sarrazin-Baudoux, C.; Leost, L.; Hervier, Z.; 2016. Near-threshold fatigue propagation of physically short and long cracks in Titanium alloy. Procedia Structural Integrity 2, 950–957; DOI:10.1016/j.prostr.2016.06.122. Doremus, L.; Nadot, Y.; Henaff, G.; Mary, C.; Pierret, S.; 2015. Calibration of the potential drop method for monitoring small crack growth from surface anomalies – Crack front marking technique and finite element simulations. International Journal of Fatigue 70, 167-187; DOI: 10.1016/j.ijfatigue.2014.09.003. Enmark, M.; Lucas, G.; Odette, G. R.; 1992. An electric potential drop technique for characterizing part-through surface cracks. Journal of Nuclear Materials 191-194, 1038-1041; DOI: 10.1016/0022-3115(92)90632-U. Hartweg, M.; Bär, J.; 2019. Analysis of the crack location in notched steel bars with multiple DC potential drop measurement, Procedia Structural Integrity 17, 254-261; DOI: 10.1016/j.prostr.2019.08.034 Johnson, H. H.; 1965. Calibrating the Electric Potential Method for Studying Slow Crack Growth. Materials Research and Standards 5, No. 9, 442– 445. Lambourg, A.; Henaff, G.; Nadot, Y.; Gourdin, S.; Pujol d'Andrebo, Q.; Pierret, S.; 2020. Optimization of the DCPD technique for monitoring the crack propagation from notch root in localized plasticity. International Journal of Fatigue 130, 105228; DOI:10.1016/j.ijfatigue.2019.105228. Meriaux, J.; Fouvry, S.; Kubiak, K.J.; Deyber, S.; 2010. Characterization of crack nucleation in TA6V under fretting–fatigue loading using the potential drop technique. International Journal of Fatigue 32, 1658–1668; doi:10.1016/j.ijfatigue.2010.03.008. Ritchie, R.O.; Garrett, G.G.; Knott, J.F.; 1971. Crack-Growth Monitoring: Optimisation of the Electrical Potential Method Using an Analogue Method. International Journal of Fracture Mechanics 7, 462–467. Si, Y.; Rouse, J.P.; Hyde, C.J.; 2020. Potential difference methods for measuring crack growth: A review. International Journal of Fatigue 136, 105624; DOI: 10.1016/j.ijfatigue.2020.105624. Tada, N.; Uchida, M.; Funakoshi, A.; Ishikawa, H.; 2011. Experimental Study of Three-Dimensional Identification of Semi-Elliptical Crack on the Back Surface by Means of Direct-Current Electrical Potential Difference Method of Multiple-Point Measurement Type. J. Pressure Vessel Technol. 133, 014502; DOI: 10.1115/1.4001918. Tesch, A.; Pippan, R.; Döker, H.; 2007 New testing procedure to determine da/dN– Δ K curves at different, constant R-values using one single specimen. International Journal of Fatigue 29, 1220–1228; DOI:10.1016/j.ijfatigue.2006.10.022. Verpoest, I.; Aernoudt, E.; Deruyttere, A.; Neyrinck, M.; 1981. An Improved A.C. Potential Drop Method for Detecting Surface Microcracks during Fatigue Tests of Unnotched Specimens. Fatigue & Fracture of Engineering Materials & Structures 3, 203–217; DOI: 10.1111/j.1460 2695.1980.TB01360.x. Wiehler, L.; Bär, J.; 2020. Crack Detection and Localization with Multiple Potential Drop Measurements. Procedia Structural Integrity 28, 925-932; DOI: 10.1016/j.prostr.2020.11.065.