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laws:chab
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CHAB
Description
Chaboche elasto-visco-plastic constitutive model with thermal and cyclic effects for solid elements at constant or variable temperatures with damage computation.
The model is highly adjustable and can be used for very simple laws (elastic, bilinear plasticity) as well as for more complex behaviors (visco-plasticity, isotropic hardening, kinematic hardening, cyclic hardening, …)
Implemented by: Hélène Morch, 2016-2019
Files
Prepro: LCHAB.F
Lagamine: CHAB.F, CHABDAM.F
Availability
| Plane stress state | NO |
| Plane strain state | NO |
| Axisymmetric state | NO |
| 3D state | YES |
| Generalized plane state | NO |
Input file
Parameters defining the type of constitutive law
| (2I5, 60A1) | |
|---|---|
| IL | Law number |
| ITYPE | 271 |
| COMMENT | Any comment (up to 60 characters) that will be reproduced on the output listing |
Integer parameters
| (9I5) | |
|---|---|
| NTEMP | number of temperatures at which material data is given |
| IANISOTH | = 1 if effect of maximum temperature in the loading history taken into account |
| = 0 else | |
| MAXITER | Maximum number of iterations for Newton-Raphson convergence (default = 25) |
| NAF | Number of Armstrong-Fredericks equations used to define the back-stress X (minimum value=1) |
| NAFY | Number of Armstrong-Fredericks equations taking into account evolution of the mean stress |
| NAFcyc | Number of Armstrong-Fredericks equations taking into account cyclic hardening |
| NINTV | number of time sub-steps in the material law |
| IDAM | = 1 for isotropic uncoupled damage computation |
| = 2 for isotropic coupled damage computation | |
| = 0 for no damage computation | |
| IARRH | = 1 expression of static recovery parameters using Arrhenius law |
| = 2 expression of all parameters as exponential function of temperature | |
| = 0 parameters are interpolated linearly between to defined temperatures | |
| ILCF | = 1 computation of stress amplitude for cyclic loading (for Optim) |
Real parameters
Parameters not depending on the temperature
| Line 1 (4G10) | |
|---|---|
| ETA | strain memory rate |
| PRECNR | precision for convergence of the Newton-Raphson algorithm (default=10-4) |
| PERIOD | period of cyclic loading (only if ILCF=1) |
| tH | Hold time in the cyclic loading (only if ILCF=1) |
| If IANISOTH=1 - Line 2 (3G10) | |
| BDG | Rate parameter controlling the evolution of Dγ |
| be | Rate of evolution of the weighted average factor fe |
| fes | Saturation value of the weighted average factor fe |
| If IDAM≠0 - Line 3 (2G10) | |
| h | micro-defects closure parameter (=0.2 in general for metals ; 1 if micro-defects closure not taken into account) |
| Dc | Critical damage value (<1) |
| τ | Specific time for the appearance of creep |
| If IARRH=1 - Line 3+i (i=1:nAF) (2G10)*i | |
| Ai | coefficient for expression of bi using Arrhenius equation |
| Bi | coefficient for expression of bi using Arrhenius equation |
Temperature-dependent parameters - Case where iarrh=0 or iarrh=1
2+IANISOTH+NAF+NAFcyc+NAFY lines repeated NTEMP times
Parameters must be introduced by increasing temperature order
| Line 1 (4G10) | |
|---|---|
| T | Temperature |
| E | Young's modulus at temperature T |
| NU | Poisson's ratio at temperature T |
| α | Thermal expansion coefficient at temperature T NB: in the preprocessor, the thermal expansion coefficient is transformed in its enthalpic formulation |
| Line 2 (5G10) | |
| σY | Yield stress at temperature T |
| b | Rate of isotropic hardening NB: to avoid convergence issues, b should be constant with temperature |
| Q | Total isotropic saturation size of the yield surface NB: to avoid convergence issues, Q should be constant with temperature |
| K | Drag stress in Norton-Hoff law |
| n | Viscosity exponent for Norton-Hoff law |
| Line 2+i (4G10) repeated NAF times (i=1:NAF) | |
| Ci | Prager's linear coefficient in the ith A-F equation |
| γi | Dynamic recovery parameter in the ith A-F equation |
| bi | Static recovery parameter in the ith equation |
| ri | Static recovery exponent in the ith equation |
| Line 2+NAF+i (4G10) repeated NAFcyc times (i=1:NAFcyc) | |
| Dγi | Parameter controlling the evolution of γi with increment of plastic strain norm |
| Aγi | Parameter controlling the saturation value of γi |
| Bγi | Parameter controlling the saturation value of γi |
| Cγi | Parameter controlling the saturation value of γi |
| Line 2+NAF+NAFcyc+i (4G10) repeated NAFY times (i=1:NAFY) | |
| αbi | Rate of evolution of the mean stress tensor Yi |
| Yst,i | Saturation value of the mean stress tensor Yi |
| If IDAM=1 - Line 2+NAF+NAFcyc+NAFY (8G10) | |
| A | Parameter of correction in the energy stored by hardening |
| m | Exponent parameter of correction in the energy stored by hardening |
| wD | Stored energy threshold for damage initiation |
| Sf | Fatigue damage parameter |
| expsf | Fatigue damage exponent parameter |
| Sc | Creep damage parameter |
| expsc | Creep damage exponent |
| k | Kachanov creep damage exponent |
Temperature-dependent parameters - Case where iarrh=2
laws/chab.1551701544.txt.gz · Last modified: 2020/08/25 15:34 (external edit)
