/FAIL/NXT
Block Format Keyword Describes the forming limit based on stresses. This failure model is available for Shell only.
Format
(1) | (2) | (3) | (4) | (5) | (6) | (7) | (8) | (9) | (10) |
---|---|---|---|---|---|---|---|---|---|
/FAIL/NXT/mat_ID/unit_ID | |||||||||
fct_ID1 | fct_ID2 | Ifail_sh |
(1) | (2) | (3) | (4) | (5) | (6) | (7) | (8) | (9) | (10) |
---|---|---|---|---|---|---|---|---|---|
fail_ID |
Definitions
Field | Contents | SI Unit Example |
---|---|---|
mat_ID | Material
identifier. (Integer, maximum 10 digits) |
|
unit_ID | Unit Identifier. (Integer, maximum 10 digits) |
|
fct_ID1 | Function identifier of
lower limit for fracture (S-R mode). (Integer) |
|
fct_ID2 | Function identifier of
upper limit for fracture (3D mode). (Integer) |
|
Ifail_sh | Shell failure flag.
(Integer) |
|
fail_ID | Failure criteria identifier. 5 (Integer, maximum 10 digits) |
Example (Steel)
#RADIOSS STARTER
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/UNIT/1
unit for mat
Mg mm s
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
#- 2. MATERIALS:
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/MAT/HILL/1/1
void_steel
# RHO_I
7.8E-9
# E NU
210000 .3
# A EPSILON_0 n EPS_max SIGMA_max
582 0.009 .258 0 0
# EPS_DOT_0 m
0 0
# r00 r45 r90 Iyield0
1.0 1.0 1.0 0
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/FAIL/NXT/1/1
# fct_ID1 fct_ID2 Ifail_sh
100 101 1
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/FUNCT/100
SR-mode
# X Y
-1.2 1.2
-1 1.3
-0.8 1.36
-0.6 1.42
-0.4 1.47
0.2 1.5
0.4 1.45
0.6 1.33
1 1.5
1.5 1.85
2 2.25
2.5 2.55
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/FUNCT/101
3D-mode
# X Y
-1.3 1.35
-1.1 1.6
-0.9 1.9
-0.7 2.2
-0.5 2.55
-0.3 2.85
-0.1 3.15
0 3.2
0.3 3.15
0.7 2.95
1.1 2.7
1.3 2.65
1.5 2.7
1.9 2.8
2.3 2.95
2.7 3.1
3.1 3.2
/MOVE_FUNCT/101
scale for 3D-mode
# Ascalex Fscaley Ashiftx Fshifty
0 2.0 0 0
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
#ENDDATA
/END
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
Comments
- A method to predict the fracture limit during a metal forming process based on the localized bifurcation theory and the instability theory for elastoplastic material.
- The forming limit diagram as presented
in Figure 1 is represented in the
plane where,
is the stress and h is the current
work-hardening modulus. The limit curves, SR and 3D represent the Stӧren-Rice's mode
(S-R) limit and the 3-dimensional localized mode limit respectively. The SR limit
can be regarded as the lower limit and the 3D limit and the upper limit for
fracture. The fracture should occur when the stress level reaches the 3D limit.
- To determine the failure zone, an
instability factor is defined as:
(1) According to the value of , the status for fracture is:
Free: if
Warning: if
Danger: if . In this case, the element failed. In this case, is set equal to 2.
- When this failure model is defined, it
automatically generates animation files containing three new outputs which are the
instability fracture
(NXT failure factor),
(SIGMA1/h), and
(SIGMA2/h).
Where, and are the two current principal stresses.
- The fail_ID is used with /STATE/BRICK/FAIL and /INIBRI/FAIL. There is no default value. If the line is blank, no value will be output for failure model variables in the /INIBRI/FAIL (written in .sta file with /STATE/BRICK/FAIL option).
- Available laws with this criterion are LAW2, LAW32, LAW36, LAW43, LAW73, and LAW78.