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laws:prevost
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PREVOST
Description
Nested surface model.
The model
This law is used for mechanical analysis of the cyclic behaviour of soils, with or without cohesion.
Files
Prepro: LPREVO.F
Lagamine: PREVOST.F
Availability
| Plane stress state | NO |
| Plane strain state | YES |
| Axisymmetric state | YES |
| 3D state | YES |
| Generalized plane state | NO |
Input file
Parameters defining the type of constitutive law
| Line 1 (2I5, 60A1) | |
|---|---|
| IL | Law number |
| ITYPE | 612 |
| COMMNT | Any comment (up to 60 characters) that will be reproduced on the output listing |
Integer parameters
| Line 1 (6I5) | |
|---|---|
| NINTV | = 0 : by default |
| ISOL | = 0 : Use of total stresses in the constitutive law |
| $\neq$ 0 : Use of effective stresses in the constitutive law (See annex 7) | |
| KRES | Resolution method (=1, 2 is not available any more) |
| ILODEF | Not used any more |
| ILODEG | Not used any more |
| ISURF | Surface type and hardening direction |
| = 1 : Von Mises shape | |
| = 2 : Drucker Prager shape and Mroz hardening rule | |
| = 3 : Drucker Prager shape and Prager hardening rule | |
| KMETH | = 2 : Actualised vgrad method |
| = 3 : Mean vgrad method (default) | |
Real parameters
| Line 1 (5G10.0) | |
|---|---|
| E | YOUNG's elastic modulus |
| ANU | POISSON's ratio |
| RHO | Specific mass |
| NSURF | Number of nested surfaces |
| DIV | DIV parameter |
| Line 2 (5G10.0) | |
| ACOH | $p'_0$ : Cohesion parameter (see Cerfontaine’s thesis) |
| IPVOL | = 0 : Basic volumetric hardening direction (P“) (default) |
| = 1 : Modified hardening direction | |
| ETA1 | First parameter of P” |
| ETA2 | Second parameter of P“ |
| ETA3 | Third parameter of P” |
| Line 3 (5G10.0) | |
| ANMAT | $p$-dependency of the stiffness, exponent $n$ |
| PREF | Reference pressure for the p-dependency |
| FMIN | Minimum pressure for the p-dependency |
| ARRET1 | First criterion of the local iterative process (variation/relative residual) |
| ARRET2 | Second criterion of the local iterative process (absolute residual) |
If IANA ≠ 4 (2D state)
| Line 4 (6G10.0) - Repeated NSURF times | |
|---|---|
| AH | Plastic modulus associated to surface i |
| AM | Radius associated to surface i |
| ALPHA(1) | Component of the backstress tensor ($\alpha_{11}$) |
| ALPHA(2) | Component of the backstress tensor ($\alpha_{22}$) |
| ALPHA(3) | Component of the backstress tensor ($\alpha_{33}$) |
| ALPHA(4) | Component of the backstress tensor ($\alpha_{12}$) |
Else if IANA = 4 (3D state)
| Line 4 (8G10.0) - repeated NSURF times | |
|---|---|
| AH | Plastic modulus associated to surface i |
| AM | Radius associated to surface i |
| ALPHA(1) | Component of the backstress tensor ($\alpha_{11}$) |
| ALPHA(2) | Component of the backstress tensor ($\alpha_{22}$) |
| ALPHA(3) | Component of the backstress tensor ($\alpha_{33}$) |
| ALPHA(4) | Component of the backstress tensor ($\alpha_{12}$) |
| ALPHA(5) | Component of the backstress tensor ($\alpha_{13}$) |
| ALPHA(6) | Component of the backstress tensor ($\alpha_{23}$) |
Stresses
Number of stresses
6 for 3D state
4 for the other cases
Meaning
The stresses are the components of CAUCHY stress tensor in global (X,Y,Z) coordinates.
For the 3-D state:
| SIG(1) | $\sigma_{xx}$ |
| SIG(2) | $\sigma_{yy}$ |
| SIG(3) | $\sigma_{zz}$ |
| SIG(4) | $\sigma_{xy}$ |
| SIG(5) | $\sigma_{xz}$ |
| SIG(6) | $\sigma_{yz}$ |
For the other cases:
| SIG(1) | $\sigma_{xx}$ |
| SIG(2) | $\sigma_{yy}$ |
| SIG(3) | $\sigma_{xy}$ |
| SIG(4) | $\sigma_{zz}$ |
State variables
Number of state variables
7
List of state variables
| Q(1) | Element thickness ($t$) in plane stress state |
| = 1 : Plane strain state | |
| Circumferential strain rate ($\varepsilon_r$) in axisymmetrical state | |
| = 0 : 3D state | |
| Element thickness ($t$) in generalized plane state | |
| Q(2) | Nothing |
| Q(3) | IYIELD : Active surface |
| Q(4) | ALIQU : Liquefaction indicator |
| = 1 if liquefaction | |
| = 0 otherwise | |
| Q(5) | TESTQM : $\rvert\rvert Q'_{n+1}\rvert\rvert$ |
| Q(6) | VOLUM : Volumetric deformation |
| Q(7) | DGAMMA |
| Q(8) | $\varepsilon_{xx}$ |
| Q(9) | $\varepsilon_{yy}$ |
| Q(10) | $\varepsilon_{zz}$ |
| Q(11) | $\varepsilon_{xy}$ |
| Q(12) | $\varepsilon_{xz}$ (if 3D) |
| Q(13) | $\varepsilon_{yz}$ (if 3D) |
| Q(14) | Previous time step |
| Q(15) | $\eta=\frac{q}{p'}$ |
| Q(16:) | AH(i) : Does not change but might |
| Q(17:) | AM(i) : Does not change but might |
| Q(18:) | ALPHA(i,1) |
| Q(19:) | ALPHA(i,2) |
| Q(20:) | ALPHA(i,3) |
| Q(21:) | ALPHA(i,4) |
| Q(22:) | ALPHA(i,5) if 3D |
| Q(23:) | ALPHA(i,6) if 3D |
laws/prevost.txt · Last modified: 2020/08/25 15:46 (external edit)
