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FAIL2D
Interface 2D fault
Description
Type: 210
The element consists of 2, 3, 4, or 5 nodes (line, parabola) and is related to a predefined foundation or tool. This element is dedicated to soil mechanics and in particular to structure-structure contact (fault). It includes pressure, friction, flow axial to the fault, the flow transversal to the fault (along the thickness).
Convention: when the element is considered in increasing order of nodes (1 → 2 → 3), the first body is to the left, and the tool or foundation to the right.
This element can be used with:
- mechanical law INTME2/INTME3 and flow law INTEC2 (the transversal flow is then computed in the flow law);
The element is compatible with plane stress state, plane strain state, and generalized plane state, as well as axisymmetric state. It can be used for mechanical, thermal, or thermo-mechanical analysis.
Implemented by: R. Charlier, 1989 (taken from CNTCP)
Files
Prepro: FAIL2A.F
Lagamine: FAIL2B.F
Input file
| Title (A5) | |
|---|---|
| TITLE | “FAIL2” in the first 5 columns |
| Control data (3I5) | |
| NELEM | Number of elements |
| INSIG | = 0 no initial stresses |
| = 1 or 2 → initial stresses | |
| IDOMA | Number of the ES group to which the elements are connected (necessary in case of remeshing) |
| Initial stresses - only if INSIG = 1 | |
| If law = COU2DC or INTME2/INTME3 (4G10.0) | |
| The pressure varies as: $PRESS = PRESS0 + (Y*DPRES) \text{ for } P\geq 0$ Tau varies as: $TAU = TAU0+(Y*DTAU)$ |
|
| PRES0 | Pressure of the contact at the axis origin |
| DPRES | Coefficient of variation of the pressure along Y (= 0 → constant pressure) |
| TAU0 | TAU at the axis origin |
| DTAU | Coefficient of variation of TAU along Y (= 0 → constant TAU) |
| If law ≠ COU2DC or INTME2/INTME3 (7G10.0) | |
| All stresses vary as: $SIGnn=SI0nn+(Y*DSIG)$ | |
| SI0nn | Stresses at the axis origin (y=0) expressed in local axes |
| SI0tt | |
| SI0nt | |
| SI0zz | |
| DSIG | Coefficient of stress variation along Y ( = 0 → constant SIGnn) |
| DTAU | |
| RIGM | Penalty = 1.0 by default = 1/e inverse of the element thickness |
| Definition of the elements (6I5/3I5) | |
| NINTE | Number of integration points (1 to 10, 5 max can be drawn by DESFIN - recommanded value: 2) |
| LMATM | Mechanical law number |
| LMATF | Flow law |
| IFOND | Number of the foundation or tool If the foundation number is equal to 0, the boundary thermal flow is calculated with the ambient, without mechanical contact with any foundation. |
| INTYP | Type of numerical integration (recommanded value: 0) 0 → Gauss 1 → Lobatto 2 → Newton-Cote |
| IRIGF | Type of contact |
| 0 → rigid foundation or tool | |
| 1 → uncoupled solid/solid contact One contact element on each structure, the interpenetration distance is divided by 2. Suitable for solids with similar stiffnesses. |
|
| 2 → coupled solid/solid contact Only one contact element must be defined on a solid, the other being its foundation. The computation of MBAND and NHICO must be actualized (see ISTRA(4)). Suitable for solids of different stiffnesses, with one (the foundation) can be more roughly approximated. |
|
| 3 → coupled solid/solid contact One contact element on each structure, the force is divided by 2. None of the structure is privileged. The computation of MBAND and NHICO must be actualized (see ISTRA(4)). Suitable for solids of different stiffnesses, both must be properly represented. |
|
| NODES(3) | List of nodes (2, 3, 4, or 5) |
Results
If the law is COU2DC or INTME2/INTME3:
Stresses: pressure, tangent stress, 0, 0, longitudinal flow, stored flow, transversal flow
Internal variables: The first values are the ones relating to the law (for INTME2/INTME3, this will be: plasticity indicator, dissipation, fault closing $V$, fault opening $D$).
The 6 next values correspond to the contact geometry. They are:
- The segment number of the foundation in contact
- The interpenetration distance
- The jacobian
- NOCO the contact indicator given by CALFON
- The relative tangent rate
- The relative sliding
The last values are those relating to the flow law; for INTEC2, they are:
- 0
- The longitudinal peremability
- The transversal transmissivity
If the law is not COU2DC or INTME2/INTME3:
Stresses:
- $\sigma_{11}$, $\sigma_{22}$, $\sigma_{12}$, $\sigma_{33}$ in local axes
- Longitudinal flow, stored flow, transversal flow
