PSI - Issue 5

G. Lesiuk et al. / Procedia Structural Integrity 5 (2017) 928–934 Lesiuk et al./ Structural Integrity Procedia 00 (2017) 000 – 000

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fully electronic switching of the capacitors with the use of MOSFET transistors was applied. The current generator for accomplishing the electro-pulsation has been shown in Figure 2. Figure 3 presents implementation of the method of leading the current to the sample.

Fig. 2. The super-capacitor current pulse generator system; 1 – current pulse generator, 2 – electrodes, 3 – specimen.

Current was supplied to the specimen by means of copper wires and screw terminals. The positive square current pulses were applied with the following parameters: impulse duration t i, and the period t o (Fig.4). The current parameters for individual specimens for the total trial time 7s and a period equal 1 ms: 1- ti, = 300 µs, 2- ti, = 200 µs, 3- ti, = 100 µs, 4- ti, = 50 µs. This way two groups of specimens were prepared for the tests: without exposure to the current and after the exposition to current – accomplished after a defined number of cycles corresponding to the nucleation phase of sub-micro cracks.

Fig. 3. The magnified view on tested specimen (1) with the current supplying electrodes (2).

Fig. 4. Parameters of the impulse current Experimental results and discussion.