PSI - Issue 21

Tuncay Yalçinkaya et al. / Procedia Structural Integrity 21 (2019) 52–60 Yalc¸inkaya et al. / Structural Integrity Procedia 00 (2019) 000–000

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6

3. Numerical Results In this section the performance of the developed model is tested through numerical simulations conducted in Abaqus software for the SS316 austenitic steel presented in Fig. 5 and deformed under compact tension. A curve fit of the hardening data is used. The specimen has 120 µ m length and 100 µ m width, which is prepared according to ASTM-E399 standards. For the bulk response isotropic elasticity and experimental plasticity data is used, while cohe sive zone elements are inserted ahead of the notch. The obtained micromechanics based traction-separation relations are implemented as user element subroutine (UEL) in Abaqus software based on the PPR model (see Cerrone et al. (2014)).

SS316 austenitic steel

500

400

300

11 - true

200

100

True Stress vs True Strain data Curve fit

0

0

0.05

0.1

0.15

0.2

11 - true

Fig. 5. True stress-strain data for SS316LN steel

(Avg: 75%) S, Mises

(Avg: 75%) S, Mises

(Avg: 75%) S, Mises

0.000 35.417 70.833 106.250 141.667 177.083 212.500 247.917 283.333 318.750 354.167 389.583 425.000

0.000 35.417 70.833 106.250 141.667 177.083 212.500 247.917 283.333 318.750 354.167 389.583 425.000

0.000 35.417 70.833 106.250 141.667 177.083 212.500 247.917 283.333 318.750 354.167 389.583 425.000 441.468

Y

Y

Y

Z

X

Z

X

Z

X

(Avg: 75%) S, S22

(Avg: 75%) S, S22

(Avg: 75%) S, S22

−300.000 −200.000 −100.000 0.000 100.000 200.000 300.000 400.000 500.000 600.000 700.000 800.000 900.000

−300.000 −200.000 −100.000 0.000 100.000 200.000 300.000 400.000 500.000 600.000 700.000 800.000 900.000

−300.000 −200.000 −100.000 0.000 100.000 200.000 300.000 400.000 500.000 600.000 700.000 800.000 900.000 −307.423 955.861

Y

Y

Y

Z

X

Z

X

Z

X

Fig. 6. Stress distributions for di ff erent initial pore fractions

In Fig. 6 the e ff ect of the initial porosity ahead of the crack tip is illustrated in CT specimen. The von Mises stress and the stress in the loading direction distribution are shown just before the crack starts to propagate, which