PSI - Issue 47

G. Anglani et al. / Procedia Structural Integrity 47 (2023) 552–562

559

8

G. Anglani et al. / Structural Integrity Procedia 00 (2023) 000–000

AE Rate and Force - Not Collapsed Specimen

AE Rate and Force - Collapsed Specimen

200

1500

150

1000

180

900

160

800

140

700

1000

100

120

600

100

500

80

400

Force [N]

Force [N]

500

50

60

300

40

200

Accumulated N of AE events

Accumulated N of AE events

20

100

0

0

0

0

025

50

0

150

250

350

450

550

650

750

850

950

1050

1150

1250

1350

1450

1550

1650

1750

1850

1950

2050

2150

2250

2350

2450

2550

2650

2750

2850

2950

3050

3150

3250

3350

3450

3550

3650

3750

3850

3950

4050

4150

4250

4350

4450

4550

4650

4750

4850 5000

25

50

100

150

200

250

300

350

400

450

500

550

600

721

N of cycles

N of cycles

(a)

(b)

Fig. 6: Load vs N of cycles curve and Accumulated N of AE events vs N of cycles curve of an uncollapsed (a) and a collapsed (b) PUC specimen.

The evolution of the Felicity Ratio can be seen in Figures 7a and 7b, and of the Calm Ratio in Figures 7c and 7d. For the uncollapsed specimen, it can be seen that both Felicity Ratio and Calm Ratio remain overall constant. Moreover, the Felicity Ratio remains high (around 0.8) and the Calm Ratio remains low (around 0.25–0.35). In the case of the collapsed specimen the situation is very di ff erent. The Felicity Ratio starts high (around 0.7) and ends very low (close to zero), while the Calm Ratio starts low (around 0.4) and finishes high (around 0.75). This is an indicator of severe damage in the specimen. The state of damage can be resumed in the damage assessment diagram, represented in Figure 8a. The values plotted are the means of the Felicity Ratio and the Calm Ratio along all cycles with AE activity. For the uncollapsed specimen, an additional static test was realized after the fatigue testing, to quantify the performance of the self-healing resin after fatigue. The load-displacement curve, as well as the fracture energy, can be seen on Figure 8b. It can be seen that the resin maintains good performance, even after the fatigue tests. The results are summarized in Table 1.

Felicity Ratio vs N of cycles - Not Collapsed Specimen

Felicity Ratio vs N of cycles - Collapsed Specimen

1

1

0.8

0.8

0.6

0.6

0.4

0.4

Felicity Ratio

Felicity Ratio

0.2

0.2

0

640 650 660 670 680 690 700 710 720 N of cycles 0

1000

2000

3000

4000

N of cycles

(a)

(b)

Calm Ratio vs N of cycles - Not Collapsed Specimen

Calm Ratio vs N of cycles - Collapsed Specimen

1

1

0.8

0.8

0.6

0.6

0.4

0.4

Calm Ratio

Calm Ratio

0.2

0.2

0

0

1000

2000

3000

4000

640

660

680

700

720

N of cycles

N of cycles

(c)

(d)

Fig. 7: Evolution of Felicity and Calm Ratios with the N of cycles for the uncollapsed (a,c) and collapsed (b,d) specimens.