PSI - Issue 2_B

G. Mirone et al. / Procedia Structural Integrity 2 (2016) 974–985 Author name / Structural Integrity Procedia 00 (2016) 000–000

976

3

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

1.7

Area Reduction Percentage

J-C dyn. Ampl.

1.6

1.5

Experimental (Noble et al.) FEM - 785MPa 200 micros. D3mm

J-C dyn. Ampl.

1.4

1.3

1.2

1.1

time [ms]

10000 20000 30000 40000 50000 60000 S.R.[s-1]

1

0

25

50

75 100 125 150 175 200

0

Figure 1: experimental valiudation of the material parameters for the Remco Iron (Mirone 2013)

0.006

60000

SIM#1 SIM#2 SIM#3 SIM#4 'SIM#1 'SIM#2 'SIM#3 'SIM#4

strain

Elastic strain on bars

Strain rate [s-1]

0.005

50000

SIM#1 input SIM#2 input SIM#3 input SIM#4 input

0.004

40000

0.003

30000

TRUE

0.002

20000

0.001

10000

ENG

strain

time [s]

0

0

0

0.3

0.6

0.9

1.2

1.5

0

0.0001

0.0002

0.0003

0.0004

Figure 2: Incident waves and true strain rate s simulated on the Remco Iron

1400

True Strain rate [s-1]

1

1200

 Eq /  True

0.8

1000

MLR POLY SIM1 - Avg Mises stress from FE SIM2 - Avg Mises stress from FE SIM3 - Avg Mises stress from FE SIM4 - Avg Mises stress from FE

800

0.6

SIM#1 SIM#2 SIM#3 SIM#4

600

0.4

400

0.2

200

Post-necking strain

True strain

0

0

0

0.3

0.6

0.9

1.2

0

0.3

0.6

0.9

1.2

1.5

Figure 3: Mises stress/True stress ratio against MLR function for the Remco Iron

It is worth noting that, after necking initiation, the true strain rate vs. true strain curves largely diverge from the corresponding curves expressing the engineering strain rate vs. eng. strain, as properly depicted in Figure 2. After such departure, the true strain rate is increased up to 6-8 times more than the engineering one.