PSI - Issue 3

G.M. Domínguez Almaraz et al. / Procedia Structural Integrity 3 (2017) 571–578 Author name / Structural Integrity Procedia 00 (2017) 000–000

575

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be observed: 1) ultrasonic fatigue endurance decreases as the displacements at the end of the awl increase, 2) mean testing temperature increases with the awl displacements, 3) maximum temperature and maximum stress were located at the contact zone between the awl and the Nafion 115 strip, and close to clamped ends of strip. In Figure 4 are shown the mean temperature obtained by a thermographic camera for the tests: 1, 3, 4, 8, 12, 13, 16 and 18, listed on Table 2.

Table 2. Ultrasonic experimental results on the Nafion 115 strip, under three points bending modality. Test Number Ultrasonic vibration displacement ( µ m) Mean testing temperature (° C) Fatigue life (Number of cycles)

1 2 3 4 5 6 7 8 9

13 13 14 15 16 18 19 19 20 20 21 21 23 23 24 24 25 25

32.0 30.0 36.0 37.0 40.0 38.0 50.0 47.0 50.0 50.0 47.0 52.0 55.0 55.0 60.0 58.0 48.0 49.0

5.0 x 10 6 5.6 x 10 6 4.0 x 10 6 5.1 x 10 6 5.3 x 10 6 2.3 x 10 6 3.8 x 10 6 3.1 x 10 6 1.5 x 10 6 2.8 x 10 6 2.5 x 10 6 8.0 x 10 5 9.7 x 10 5 1.1 x 10 6 8.1 x 10 5 5,7 x 10 5 5.9 x 10 5 1.0 x 10 6

10 11 12 13 14 15 16 17 18

Fig. 4. Thermographic images of testing specimens: 1 (a), 3 (b), 4(c), 8(d), 12(e), 13(f), 16(g), and 18(h), listed on Table 2.