Issue 37

G. Cricrì et alii, Frattura ed Integrità Strutturale, 37 (2016) 333-341; DOI: 10.3221/IGF-ESIS.37.44

1

1

NODAL SOLUTION STEP=2 SUB =113 TIME=2 SY (AVG) RSYS=0 DMX =1.5 SMN =-10.117 SMX =-5.645

NODAL SOLUTION STEP=4 SUB =105 TIME=4 SY (AVG)

JUL 18 2011 19:34:24

JUL 18 2011 19:33:52

MX

RSYS=0 DMX =3

MX

SMN =-29.77 SMX =-15.389

MN

MN

Y Z

Y Z

X

X

-10.117

-9.124

-8.13

-7.136

-6.142

-29.77

-26.574

-23.378

-20.182

-16.987

-9.621

-8.627

-7.633

-6.639

-5.645

-28.172

-24.976

-21.78

-18.585

-15.389

1

1

NODAL SOLUTION STEP=5 SUB =105 TIME=5 SY (AVG)

NODAL SOLUTION STEP=6 SUB =105 TIME=6 SY (AVG)

JUL 18 2011 19:33:18

JUL 18 2011 19:26:29

RSYS=0 DMX =4

RSYS=0 DMX =6

MX

SMN =-74.449 SMX =-39.655

SMN =-732.132 SMX =-408.093

MX

MN

MN

Y Z

Y Z

X

X

-100

-86.667

-73.333

-60

-46.667

-732.132

-660.123

-588.115

-516.106

-444.097

-93.333

-80

-66.667

-53.333

-40

-696.128

-624.119

-552.11

-480.102

-408.093

Figure 4 : Axial stress σ y

[MPa] at different steps of compaction process (loading phase).

1

1

NODAL SOLUTION STEP=7 SUB =105 TIME=7 SY (AVG) RSYS=0 DMX =5.88 SMN =-147.778 SMX =-81.943

NODAL SOLUTION STEP=8 SUB =105 TIME=8 SY (AVG) RSYS=0 DMX =5.856 SMN =-105.222 SMX =-16.223

JUL 18 2011 19:34:41

JUL 18 2011 19:34:57

MX

MX

MN

MN

Y Z

Y Z

X

X

-147.778

-133.148

-118.518

-103.888

-89.258

-105.222

-85.444

-65.667

-45.889

-26.112

-140.463

-125.833

-111.203

-96.573

-81.943

-95.333

-75.555

-55.778

-36

-16.223

Figure 5 : Axial stress σ y

[MPa] at different steps of compaction process (unloading phase).

In Figures 6-7 numerical results of pressure exerted by metal powder on die walls are shown, considering the step of maximum loading exerted by punches and friction coefficient equal to  = 0.1 and   = 0.05, respectively. Contact pressure distribution is not uniform along surfaces of punches and die walls, because of powder mechanical behaviour, strongly influenced by local and global friction. Contact pressure exerted on upper and lower punches reaches a peak in the edges close to die walls, where friction stress is maximum, whilst presents a mean value of 570 MPa in the zones far from edges. Specifically, peak values are equal to an increase by 15% and 7% than mean outcome, when friction coefficient is   = 0.1 and  = 0.05 respectively.

338