PSI - Issue 13

Yanning Guo et al. / Procedia Structural Integrity 13 (2018) 806–812 Yanning Guo/ Structural Integrity Procedia 00 (2018) 000 – 000

810

5

Fig.4 shows the stress-strain curves of 2024 under different strain rates. With the strain rate increasing, the yield strength of sample at 2600 s -1 increases significantly. Thus it can be deduced that the yield strength of 2024 are affected by the strain rate during the plastic deformation stage. This is because the higher strain rate is not helpful to the continuity of material interior grain slippage, which will easily induce stress concentration and increase resistance of deformation. On the other hand, the value of peak flow stress and fracture strain is similar. The slope of all five curves remains practically constant in the elastic deformation stage. In addition, at room temperature, the elastic modulus of 2024 has low strain rate sensitivity.

a

b

500

600

400

500

400

300

300

200

200

Ture Stress (MPa)

Ture Stress (MPa)

100

1300 2600

1300 2600

100

0.00

0.05

0.10

0.15

0.20

0.25

0.00

0.05

0.10

0.15

0.20

Ture Strain

Ture Strain

c

d

600

500

500

400

400

300

300

200

200

Ture Stress (MPa)

True Stress (MPa)

1300 2600

1300 2600

100

100

e

0.00

0.05

0.10

0.15

0.20

0.25

0.00

0.05

0.10

0.15

0.20

0.25

Ture Strain

True Strain

500

400

300

200

Ture Stress (MPa)

1300 2600

100

0.00

0.05

0.10

0.15

0.20

0.25

Ture Strain

Fig.4 Comparison of 2024 stress-strain curves with different strain rate (400rmp-150mm/min): (a) Sample 1; (b) Sample 2; (c) Sample 3; (d) Sample 4; (e) Sample 5