/FAIL/COCKCROFT
Block Format Keyword A nonlinear stress-strain based failure criterion with linear damage accumulation.
Is compatible with shells and solids. Fracture occurs when the accumulated equivalent strain modified by maximum principal tensile stress reaches a critical value. Is compatible with visco-elastic and elasto-plastic materials.
Format
(1) | (2) | (3) | (4) | (5) | (6) | (7) | (8) | (9) | (10) |
---|---|---|---|---|---|---|---|---|---|
/FAIL/COCKCROFT/mat_ID/unit_ID | |||||||||
C0 | Alpha |
(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 | (Optional) Unit Identifier. (Integer, maximum 10 digits) |
|
C0 | Cockcroft–Latham failure
criterion. 1
(Real) |
|
Alpha | Exponential moving average
filter on 1st principal stress
. 4
(Real) |
|
fail_ID | (Optional) Failure criteria identifier.
(Integer, maximum 10 digits) |
Example
#RADIOSS STARTER
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/UNIT/1
unit for mat
# MUNIT LUNIT TUNIT
Mg mm s
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/MAT/PLAS_TAB/1/1
Steel
# RHO_I
7.8E-9 0
# E Nu Eps_p_max Eps_t Eps_m
210000 .3 0 0 0
# N_funct F_smooth C_hard F_cut Eps_f VP
1 0 0 0 0 0
# fct_IDp Fscale Fct_IDE EInf CE
0 0 0 0 0
# func_ID1 func_ID2 func_ID3 func_ID4 func_ID5
1
# Fscale_1 Fscale_2 Fscale_3 Fscale_4 Fscale_5
1
# Eps_dot_1 Eps_dot_2 Eps_dot_3 Eps_dot_4 Eps_dot_5
0
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/FAIL/COCKCROFT/1/1
# C0 Alpha
0.4
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
#- 3. FUNCTIONS:
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/FUNCT/1
function_36
# X Y
0.00 270.00
0.01 298.39
0.02 313.04
0.03 324.89
0.04 335.23
0.05 344.58
0.06 353.20
0.07 361.26
0.08 368.87
0.09 376.11
0.10 383.03
0.20 441.33
0.30 488.52
0.40 529.69
0.50 566.89
0.60 601.21
0.70 633.30
0.80 663.61
0.90 692.43
1.00 720.00
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
#enddata
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
Comments
- This failure criterion is
defined based on the well-known Cockcroft–Latham criterion.
(1) Where,- First principal tension stress.
- The equivalent strain.
- No failure occurs in compression.
- When this failure is used with /MAT/LAW1, only N=1 (membrane) is supported. It does not work when N=0 global integration is used.
- An exponential moving
average filter is used for filtering the 1st principal
stress.
(2) Where,- Filtered stress.
- Degree of weighting decrease, a constant smoothing factor between 0 and 1. A higher value discounts previous values faster, which means the stress is less filtered.