PSI - Issue 2_A

Toshiyuki Meshii et al. / Procedia Structural Integrity 2 (2016) 704–711 Toshiyuki Meshii and Kenichi Ishihara / Structural Integrity Procedia 00 (2016) 000–000

710

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Table 2 Fracture toughness test results for S55C (20 °C) B / W Serial No. 1 2



3

4

5

6

2  /  (%)



a / W

0.499 10.5 56.4 29.4 81.5 41.9 71.4 25.2 75.5 167.5 0.496 390.9

0.501

0.498 10.6 56.7 39.6 94.7 49.4 86.3 43.2 98.9 124.4 0.504 228.0

0.498

0.500

0.499

0.499

0.001

0.47 14.7 15.8 95.4 49.2 95.0 1.06 18.2 18.8 48.4 26.1 65.8

P c (kN)

11.5 61.8 66.3

10.8 57.5 41.2 96.6

11.9 65.0 94.8

12.6 67.9 96.4

11.3 60.9 61.3

0.8 4.8

1/2 )

K c (MPa m J c (N/mm) K J c (MPa m

0.5T SE(B)

0.5

29.2 28.3 35.7

1/2 )

122.5

146.5

147.7

114.9 121.4 0.499

M

74.3

119.5 0.500

52.0

51.1

a / W

0.498

0.499

0.499

0.003

P c (kN)

51.1 87.7 44.5

53.5 92.4 53.8

50.4 86.8 44.0 99.8

55.0 94.6 55.2

50.2 86.5 44.3 99.5

4.6 8.1

1/2 )

K c (MPa m J c (N/mm) K J c (MPa m

1T CT

0.5

10.7 13.0 35.4

1/2 )

100.4 221.3

110.4 183.1

111.7 178.4

M

223.9

237.6

P - V diagram for experimental results and EP-FEA results are shown in Fig. 9(a) and (b). As shown in Fig. 9, the path of the P - V diagrams for experiment and EP-FEA are very similar regarding SE(B) and 1T CT either. It was also confirmed that P s is smaller than P c for all of the test results.

(a) 0.5TSE(B)

(b) 1T CT

Fig. 9 Comparison of FEA and experimental P - V diagrams

6. Discussion In Fig. 10, J c s obtained from experiment and J s s were compared. Here,  = T 11 (  a )

1/2 / K is the biaxiality factor,

which represents the intensity of crack tip constraint.

0.5T SE(B)

1T CT

100

Jexp Js Jc(0.02)

91%

J c [N/mm]

125%

J c(0.02) :36%

J s :37%

10

0.1

1

β

Fig. 10 S55C fracture toughness test results J c compared with the predicted minimum toughness J s

As shown in Fig. 10, it is read that all of the experimental J c s for 0.5T SE(B) were larger than those for 1T CT. This was as expected, because of thickness and constraint difference. J s also predicted this tendency. J s predicted minimum observed toughness J c conservatively for 91 % and 125 % for 0.5T SE(B) and 1T CT specimens,