PSI - Issue 13

Kiiko V.M. et al. / Procedia Structural Integrity 13 (2018) 1433–1437 Author name / Structural Integrity Procedia 00 (2018) 000 – 000

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similarly to that shown in Fig. 1a. The laboratory instruments used were a stabilized TEC-18 as a constant current source and a digital multimeter Shch4300 as a voltmeter. Measurements were obtained as follows. An initial cut of 10 mm was made in the sample. An electrical current (2 amperes) was passed through the sample. An immobile voltmeter contact (“fixed point”) was placed at the end of the cut, and a movable voltmeter contact was placed at a series of points (“movable points”) such that the voltage measured by the instrument was zero. As a result, the movable point represented the position of the equipotential line passing through the fixed point. The cut (crack) was then lengthened, and the new position of the equipotential line was determined. The results are shown in Fig. 5. In addition, the dependence on the cut length l of the shift x of the exit point of the equipotential line at the edge opposite to the beginning of the cut was established (shown in Fig. 6).

Fig. 6. Dependence of the shift x of the movable contact N on the crack length l (see Fig. 2a): “points” show the results of three series of measurements, and the solid kine shows the analytic calculation results.

4. Conclusions

1. The calculated and measured fields of equipotential lines on the surface of flat specimens containing a crack practically coincide. It is important that the calculations are done based on the analytic dependence obtained in this paper. 2. The calculated dependence on the crack length of the shift of the point where an equipotential line passing through a given point intersects a line defined along the edge of the sample practically coincides with the measurement results. 3. The obtained results lead to the possibility of automatically tracking the length of a developing conductive crack and controlling the destruction process. Acknowledgements This research was supported by the Russian Foundation for Basic Research (Project: 17-08-01739 a). Markochev V. M, Bobrinsky A. P, Kiiko V. M., 1979. New method for measuring the length of conductive samples. Laboratory, vol. 45, № 9, pp. 861-862. Markachev V. M, Bobrinsky A. P, Kiyko V. M., 1978. Method for measuring the length of developing cracks in conductive samples and device for its implementation. Patent: 561441. Sosnin F. R., Podmasteryev K. V., 2004. Non-destructive testing: Handbook in 7 volumes. Under the editorship of Klyuev V. V.. Vol.5. № . 2: electrical control M.: mechanical engineering, pp 677. Shkatov P. N., Chernenko P.I., 2013. Measurement of depth and angle of surface cracks by electro-potential method. Vestnik MGUPI - №44 Litvinov L. N., Tsypushtanov F. G., Parks V. A., Bakumov V. N., 1988. Electro-potential crack depth meter. Patent: 1408205 Osiecki D. A., Tsvelev V. V., 1996. Method of measuring crack propagation in conductive samples. Patent: 1834491 Lavrentyev M. A., Shabat B. V., 1987. Methods of the theory of functions of complex variable. - M.: Nauka. – pp. 736. References