PSI - Issue 61

Toros Arda Akşen et al. / Procedia Structural Integrity 61 (2024) 260 – 267 Toros Arda Akşen, Bora Şener, Emre Esener, Mehmet Firat / Structural Integrity Procedia 00 (2019) 000 – 000

265

6

The quarter model was prepared due to the symmetry conditions and segment to segment contact algorithm was used and penetration between blank and dies was minimized with the Lagrange multiplier optimization method. The die tools were taken into account as rigid surfaces. The blank holder force was applied as of 85 kN due to the orthogonal symmetric feature (340 kN was employed for the entire blank in the experiment). The friction coefficient was assumed 0.125 for punch-blank interaction and 0.05 between the blank and the other tools. After applying the entire blank holder force, the die moved vertically up to fracture initiated. The FE analyses were performed with the developed numerical model and the obtained results were presented in Section 4. 4. Results FE analyses of the rectangular cup deep drawing were made with the critical damage indicator values determined by uniaxial tension and bulge tests. The estimated fracture initiation regions, and the variations of the plastic work and equivalent plastic strain with the die displacement are shown in Fig. 6 and 7, respectively.

a

Fracture initiation

b

Fig. 6. Fracture initiation zones predicted by the damage indicators of (a) uniaxial tensile test; (b) bulge test

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

100 150 200 250 300 350 400 450 500

444 MPa

Plastic Work Plastic Strain

182.417 MPa

Critical damage

indicator (Uniaxial Tensile Test)

0.504

Plastic Work (MPa)

Equivalent plastic strain(-)

0.274

0 50

Critical damage indicator (Bulge Test)

0

20

40

60

80

100

Die Displacement (mm)

Fig. 7. Evolution of plastic work and equivalent plastic strain with respect to the punch displacement