PSI - Issue 47
G. Anglani et al. / Procedia Structural Integrity 47 (2023) 552–562
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G. Anglani et al. / Structural Integrity Procedia 00 (2023) 000–000
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where A i is the amplitude of signal ” i ” in mV and ∆ t i is the duration of the signal ” i ” in s. The ” W 0 ” energy was calculated, according to [34], as the area under the load-displacement curve, obtained via the trapezium rule, according to Equation 2:
2
( δ i − δ i − 1 )
P i = 2
F i + F i − 1
(2)
W 0 =
[J] ,
where δ and F are, respectively, the displacement of the piston (in mm) and the force (in N) measured by the testing machine at two consecutive data points ”i” and ”i-1”, and P is the total number of data points acquired during the test. Examples of the load-displacement curve of virgin and self-repaired specimens are shown in the following section. The fracture energy was then calculated by dividing the ” W 0 ” energy by the ligament area, according to Equation 3 [34]:
W 0 s L
G F =
[N / m] ,
(3)
where W 0 is the total energy of Equation 2 in Joules [J], and s L is the specimen’s ligament area in m 2 . The specimens had dimensions (40 × 40 × 160)mm 3 and the notch width and height were equal to 4 mm, making the ligament area equal to (40 × 36) mm 2 , see section 2.1. The fracture energy of a virgin and a self-repaired PUC specimens can be seen in Figure 3a and 3b. The AE rate can be seen in Figure 3c and 3d for the same virgin and self-repaired specimens respectively.
PUC Virgin
PUC Self-Repaired
300
300
1400
1400
Force Fracture Energy
Force Fracture Energy
1200
1200
250
250
1000
1000
200
200
800
800
150
150
600
600
100
100
Force [N]
Force [N]
400
400
50
50
200
200
0
0
0
0
0
0.1
0.2
0.3
0
0.1
0.2
0.3
0.4
Accumulated Fracture Energy [N/m]
Accumulated Fracture Energy [N/m]
Displacement [mm]
Displacement [mm]
(a)
(b)
PUC Virgin
PUC Self-repaired
1400
100
1400
1200
1200
80
80
Force Accumulated number of AE Signals AE Rate
1000
1000
60
60
800
800
600
600
40
40
Force Accumulated number of AE Signals AE Rate
400 Force [N]
400 Force [N]
N of AE Signals
N of AE Signals
20
20
200
200
0
0 1020304050 Time [s] 0
0
0
0
50 100 150 200 250 Time [s]
(c)
(d)
Fig. 3: Load vs displacement, load vs time, and accumulated number of AE signals vs time curves of a virgin (a,c) and a self-repaired PUC (b,d) specimen subjected to static tests.
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