PSI - Issue 5

Terekhina Alena et al. / Procedia Structural Integrity 5 (2017) 569–576 Terekhina Alena et al. / Structural Integrity Procedia 00 (2017) 000 – 000

574

6

S 13 S 14 S 15 S 16 S 17 S 18 S 19 S 20 S 23 S 24 S 25 S 26 S 27 S 28 S 29 S 30 S 31 S 32 S 33

2 2 2 2 2 2 1 1 1 1 1 1 1

0.1 0.1 0.1

27.4 27.6 27.3 29.9 29.8 29.9 27.2 28.3 27.9 30.6 30.7 30.4 27.2 28.3 28.4 31.1 30.8 27

50.3 51.7 49.3

0.545 0.534 0.554

1.5788

0.027 0.027 0.027

1.705

1.5962 0.2663 0.2991 0.2938 2.6024 2.5759 2.3252 2.3752 0.5421 0.6001 0.6041 2.7095 2.2454 2.4256 2.3841 0.4565 0.6893

5 5 5

1.1 1.2 1.1

27.182 24.833 27.182

0.38

0.427 0.399

0.01 0.01

618.6

0.044 0.044 0.469 0.465

0.0046 0.0047 0.0448 0.0443

610 60.4

0.1 0.1

60

5 5 5

1.3 1.4 1.4

23.538 21.929 21.714

0.884 0.925

1.08

0.1 0.1 0.1 0.1 0.1 0.1

0.01 0.01

27.13

641.6 585.8

0.043 0.046 0.472 0.471

0.0078 0.0078

0.1 0.1

59.9 60.3

0.076 0.077

5 5

1.3 1.4

23.923

1.43

22

1.8

S 5MA S 9MA S 12MA S 6 MA

2 1 1

10.66

1.142e-5 1.372e-5 1.332e-5 1.196e-5

9.3345e+5 9.8397e+5 1.2643e+6 1.5142e+6

6362

13.5

11038 12793 27211

16.84 18.11

0.1

3.2. Identification of the Johnson-Cook parameters

The first bracket in equation (7) determined from the quasi-static tensile test at the reference strain rate of 0.0002 s -1 . The plastic strain is calculated by subtracting the elastic strain from the total strain. For the reference strain rate stress values are fitted with (A+Bε n ) as shown in Figure 4a. The fitting is performed until about 0.08 strain since above this strain level necking starts. The fitting parameters for the tensile A, B and n are shown in the same graph: A=363.1 MPa, B=389.89 MPa and n=0.435.

Fig. 4. a) Fitting curve for determing of A, B, n parameters; b) Johnson−Cook curve fitting result vs. experimental result .

To describe the influence of the strain rate effect on the deformation, the yield stress values are regarded as a function of strain rate. So, the value of the constant C is taken equal to 0.0176. At last to check the reliability of the