PSI - Issue 42

Nikola Schmidová et al. / Procedia Structural Integrity 42 (2022) 1306–1313 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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Fig. 3 Measured electrical resistance change and relative resistance moment of cyclic flexural tests.

Fig. 4 Measured electrical resistance change and relative resistance moment of quasi-static flexural tests.

Nickel coating was used for preparation of electrical conductive connection to the carbon fiber tows. Then copper wires were soldered to the ends of the carbon fiber tows. These were finally wrapped around the spindle during manufacturing the specimens, see Fig. 2 (a). Carbon fiber tows with soldered copper wires created the electrical connection to the CFRP specimens. 2.3. Experimental setup The loading of the specimens under flexural and torsional loading was carried out under ambient laboratory conditions. An IST Instron PL63N servo hydraulic cylinder was used for flexural tests. The flexural test of the composite profile with the ILT joint was performed in the configuration depicted in Fig. 1 (a). The test was carried out under displacement control at a loading speed 8 mm/min. The torsional test was carried out under ambient laboratory conditions using a servo-hydraulic torsion actuator AT-8-100-V1(Inova Praha s.r.o., Czech Republic). The specimen for torsional loading was clamped at one end to the rigid frame and at the other end the torsional moment was applied through the pin inserted in the eyelet using the loading machine, see Fig. 1 (b). The test was carried out under displacement control at a loading speed 2°/min. The change in electrical resistance was measured by 4-wire resistance measuring method using an Agilent 34401A Multimeter. The same terminals for electrical voltage and electrical current were used on the specimens, see Fig. 2. The distance between the terminals was 60 mm for the flexural specimens and for 200 mm for the torsional specimens. Our intention was to investigate also configuration with separate terminals for electrical current and electrical voltage, because this configuration should be more precise for electrical resistance measurement. Unfortunately, the second pair of electrodes was damaged during manipulation with the specimens. 3. Results and discussion 3.1. Flexural loading For each specimen initial electrical resistance was measured before mechanical loading. Measured data are given in