PSI - Issue 33

Branislav Djordjevic et al. / Procedia Structural Integrity 33 (2021) 781–787 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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Fig. 3, it can be seen that values of J c are bit a lower on B net = 20 mm specimens in comparison to one with B net =16 mm. Larger thickness provides more concervative data, but there is still a severe scatter of results. Influence of the temperature on r c - J c dependance can be observed in Fig. 4a. The values or blue and red dots represent different values of r c - J c . The blue dots have higher values than red ones and can be observed in a somewhat linear form of distribution. As for the red dots (results of testing at - 90℃) no visible distribution can be observed, but scatter of r c are seems to be larger in comparison to blue ones. Besides that, influence of thickness is also present and has to be examined. In Fig. 4b, dependence of r c and z c can be observed for the C(T)50 specimens tested at - 60℃ . Idea here was to show influence of displacement rates on the cleavage initiation sites, which r c and z c parameters represent. Scatter is obvious along with scatter of J c parameter. From this small number of results, it can be concluded that greater displacement rate during testing provide cleavage initiation more to be on the middle of the specimen, but yet more results need to confirm this statement.

700

700

600

600

500

500

400

400

Tested at - 90℃

300 J c (N/mm)

300 J c (N/mm)

200

200

100

100

Tested at - 60℃

0

0

14

15

16

17

18

19

20

21

14

16

18

20

22

thickness of specimen

thickness of specimen

a) b) Fig 3 (a) Influence of the temperature on J c scatter; (b) Influence of the specimen thickness on J c scatter (testing at -60°C)

700.0

0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60

600.0

500.0

400.0

J c (N/mm)

r c (mm)

300.0

200.0

100.0

0.0

0.00

0.50

1.00

1.50

2.00

2.50

0.00

1.00

2.00

3.00

4.00

5.00

6.00

r c (mm)

z c (mm)

C(T)50, -60°C (Btot = 20 mm)

C(T)50, -90°C (Btot = 25 mm)

v = 0,5 mm/min

v = 0,02 mm/min

Fig. 4 (a) J c - r c dependence on temperature (testing at -60 ℃ and -90 ℃ ); (b) r c - z c dependence on displacement rates (testing at -60 ℃ )

4. Conclusion Like numerous studies in this field, this one represents a statistical interpretation of the obtained results. From the obtained results and discussed parameters, few observation could be emphasized: