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Table of Contents
LICHA
Description
Constitutive law defining distributed loads on a line or a surface. Implemented by: S. Cescotto - mai 1986
The model
Definition of a uniformly distributed load (whether normal or tangent, whether in global axis) on a line (LICHA element) or on a surface (SUCHA element).
Files
Write here the names of the main subroutines of the law (those called by loi2 for Lagamine)
Prepro: LLICHA.F
Lagamine: LICHAB.F/SUCHAB.F (element subroutine)
Availability
| Plane stress state | YES |
| Plane strain state | YES |
| Axisymmetric state | YES |
| 3D state | YES |
| Generalized plane state | YES |
Input file
Parameters defining the type of constitutive law
| Line 1 (2I5, 60A1) | |
|---|---|
| IL | Law number |
| ITYPE | 95 |
| COMMENT | Any comment (up to 60 characters) that will be reproduced on the output listing |
Case 1: 2-D state (LICHA or SUCHA)
1.1 Uniform functions in local or global axes
| Line 1 (2I5) | |
|---|---|
| IVAL | = 1 in local axis |
| = 5 in global axis | |
| IMLIC | = 0 normal load for are-length method |
| = 1 dead load | |
| Line 2 (4G10.0) | |
| If IVAL = 1 | |
| PRESSF | Normal pressure |
| TAUF | Tangent load |
| PRESSD | Normal pressure |
| TAUD | Tangent load |
| If IVAL = 5 | |
| SIGXF | Total stress in X axis |
| SIGYF | Total stress in Y axis |
| SIGXD | Total stress in X axis |
| SIGYD | Total stress in Y axis |
During the non-linear analysis, PRESSF and TAUF will be multiplied by the load factor ALAMBF (= FMULT cumulated) while PRESSD and TAUD will be multiplied by the load factor ALAMBD (= DMULT cumulated).
1.2 Linear functions in local or global axis
| Line 1 (2I5) | |
|---|---|
| IVAL | = 2 in local axis |
| = 6 in global axis | |
| IMLIC | = 0 normal load for are-length method |
| = 1 dead load | |
If IVAL = 2
| Line 2 (4G10.0) | |
|---|---|
| PRESSF1 | Normal pressure for node 1 |
| TAUF1 | Tangent load for node 1 |
| PRESSD1 | Normal pressure for node 1 |
| TAUD1 | Tangent load for node 1 |
| Line 3 (4G10.0) | |
| PRESSF2 | Normal pressure for node 2 |
| TAUF2 | Tangent load for node 2 |
| PRESSD2 | Normal pressure for node 2 |
| TAUD2 | Tangent load for node 2 |
If IVAL = 6
| Line 2 (4G10.0) | |
|---|---|
| SIGXF1 | Total stress in X axis for node 1 |
| SIGYF1 | Total stress in Y axis for node 1 |
| SIGXD1 | Total stress in X axis for node 1 |
| SIGYD1 | Total stress in Y axis for node 1 |
| Line 3 (4G10.0) | |
| SIGXF2 | Total stress in X axis for node 2 |
| SIGYF2 | Total stress in Y axis for node 2 |
| SIGXD2 | Total stress in X axis for node 2 |
| SIGYD2 | Total stress in Y axis for node 2 |
Remarks:
If IVAL = 2 and NNODE = 3: Bilinear functions: The nodes N1 and N2 are the two nodes on the extremities of the LICHA element. The distributed load on node N3 is an linear interpolation of the distributed load on nodes N1 and N2.
During the non-linear analysis, PRESSF and TAUF will be multiplied by the load factor ALAMBF (= FMULT cumulated) while PRESSD and TAUD will be multiplied by the load factor ALAMBD (= DMULT cumulated).
1.3 Parabolic functions in local or global axes
| Line 1 (2I5) | |
|---|---|
| IVAL | = 3 in local axis |
| = 7 in global axis | |
| IMLIC | = 0 normal load for are-length method |
| = 1 dead load | |
If IVAL = 3
| Line 2 (4G10.0) | |
|---|---|
| PRESSF1 | Normal pressure for node 1 |
| TAUF1 | Tangent load for node 1 |
| PRESSD1 | Normal pressure for node 1 |
| TAUD1 | Tangent load for node 1 |
| Line 3 (4G10.0) | |
| PRESSF2 | Normal pressure for node 2 |
| TAUF2 | Tangent load for node 2 |
| PRESSD2 | Normal pressure for node 2 |
| TAUD2 | Tangent load for node 2 |
| Line 4 (4G10.0) | |
| PRESSF3 | Normal pressure for node 3 |
| TAUF3 | Tangent load for node 3 |
| PRESSD3 | Normal pressure for node 3 |
| TAUD3 | Tangent load for node 3 |
If IVAL = 7
| Line 2 (4G10.0) | |
|---|---|
| SIGXF1 | Total stress in X axis for node 1 |
| SIGYF1 | Total stress in Y axis for node 1 |
| SIGXD1 | Total stress in X axis for node 1 |
| SIGYD1 | Total stress in Y axis for node 1 |
| Line 3 (4G10.0) | |
| SIGXF2 | Total stress in X axis for node 2 |
| SIGYF2 | Total stress in Y axis for node 2 |
| SIGXD2 | Total stress in X axis for node 2 |
| SIGYD2 | Total stress in Y axis for node 2 |
| Line 4 (4G10.0) | |
| SIGXF3 | Total stress in X axis for node 3 |
| SIGYF3 | Total stress in Y axis for node 3 |
| SIGXD3 | Total stress in X axis for node 3 |
| SIGYD3 | Total stress in Y axis for node 3 |
Remarks:
If IVAL = 3 and NNODE = 2: Impossible
During the non-linear analysis, PRESSF and TAUF will be multiplied by the load factor ALAMBF (= FMULT cumulated) while PRESSD and TAUD will be multiplied by the load factor ALAMBD (= DMULT cumulated).
1.4 Y-dependent functions – Type 1
| Line 1 (I5) | |
|---|---|
| IVAL | = ± 4 in local axis |
| = ± 8 in global axis | |
| Line 2 (4G10.0) | |
| PRESSF | Normal pressure = PRESSA + PRESSB*y + PRESSC*y² + PRESSD*DMULT + PRESSF*FMULT |
| TAUF | |
| PRESSD | |
| TAUD | |
| Line 3 (6G10.0) | |
| PRESSA | Tangent load = TAUA + TAUB*y + TAUC*y2 + TAUD*DMULT + TAUF*FMULT y is the ordinate of the node where these stresses are applied |
| TAUA | |
| PRESSB | |
| TAUB | |
| PRESSC | |
| TAUC | |
If $F_n(y).F_n(y=0) \leq 0$ and IVAL = + 4 ⇒ $F_n= 0$ and $F_r= 0$
If $F_n(y).F_n(y=0) > 0$ and IVAL = - 4 ⇒ $F_n= 0$ and $F_r= 0$
During the non-linear analysis, PRESSF and TAUF will be multiplied by the load factor ALAMBF (= FMULT cumulated) while PRESSD and TAUD will be multiplied by the load factor ALAMBD (= DMULT cumulated).
1.5 Y-dependent functions – Type 2
| Line 1 (I5) | |
|---|---|
| IVAL | = ± 10 in local axis |
| = ± 11 in global axis | |
| Line 2 (4G10.0) | |
| PRESSF | Normal pressure = (PRESSF + PRESSA + PRESSB*y + PRESSC*y²)*FMULT + PRESSD*DMULT |
| TAUF | |
| PRESSD | |
| TAUD | |
| Line 3 (6G10.0) | |
| PRESSA | Tangent load = (TAUF + TAUA + TAUB*y + TAUC*y2)*FMULT + TAUD*DMULT y is the ordinate of the node where these stresses are applied |
| TAUA | |
| PRESSB | |
| TAUB | |
| PRESSC | |
| TAUC | |
If $F_n(y).F_n(y=0) < 0$ and IVAL = + 10 ⇒ $F_n= 0$ and $F_r= 0$
If $F_n(y).F_n(y=0) > 0$ and IVAL = - 10 ⇒ $F_n= 0$ and $F_r= 0$
During the non-linear analysis, PRESSF and TAUF will be multiplied by the load factor ALAMBF (= FMULT cumulated) while PRESSD and TAUD will be multiplied by the load factor ALAMBD (= DMULT cumulated).
1.6 Imposition gravity by SUCHA
| Line 1 (4I5) | |
|---|---|
| IVAL | = 9 |
| IMLIC | = 0 normal load for are-length method |
| = 1 dead load | |
| ISRW | = Formulation index for Sr,w |
| IMULT | = FMULT/DMULT multiplicator index |
| = 0 the gravity will be multiplied by FMULT | |
| = 1 the gravity will be multiplied by DMULT (Used only if ISRW ≠ 0) | |
If ISRW = 0
| Line 2 (2G10.0) | |
|---|---|
| PRESSF | Normal pressure |
| PRESSD | Normal pressure |
If ISRW ≠ 0
| Line 2 (3G10.0) | |
|---|---|
| GAMMAS | = $\rho_s.g$ [N/m3] |
| GAMMAW | = $\rho_w.g$ [N/m3] |
| POROS | = Soil porosity n |
| Line 3 (7G10.0) | |
| CSR1 | = 1st coefficient of the function Sr,w |
| CSR2 | = 2nd coefficient of the function Sr,w |
| CSR3 | = 3rd coefficient of the function Sr,w |
| CSR4 | = 4th coefficient of the function Sr,w |
| SRES | = Residual saturation degree ( = Sres ) |
| SRFIELD | = Field saturation degree ( = Sr,field ) |
| AIREV | = Air entry value [Pa] |
Remarks:
With IVAL = 9 and ISRW = 0, the gravity ($\rho g$) is imposed by mean of “PRESSF” multiplied by ALAMBF or “PRESSD” multiplied by ALAMBD.
With IVAL = 9 and ISRW ≠ 0, the gravity ($\rho g= (1-n) \rho_s*g+S_r*n*\rho_w *g$) is imposed and multiplied by ALAMBF if IMULT = 0, or by ALAMBD if IMULT = 1.
The obtained value (positive) will be used to impose gravity forces in the –Y direction. The SUCHA element is used so of course in a 2D analysis.
Case 2: 3-D state (SUCHA)
Stresses
Number of stresses
3 for 3D state
2 for the other cases
Meaning
For the 3-D state:
| SIG(1) | current value of the normal pressure |
| SIG(2) | current value of the tangent load in the ξ direction |
| SIG(3) | current value of the tangent load in the η direction |
For the other cases:
| SIG(1) | current value of the normal pressure |
| SIG(2) | current value of the tangent load |
State variables
Number of state variables
1
List of state variables
| Q(1) | = 0 (meaningless) |
