Table of Contents
CFI3D
3D contact element
Description
Type: 212
The element consists of 4 or 8 nodes connected to the structure. The normal (red side in DESFIN) must go out of the structure.
The foundation, defined by a series of triangular or quadrangular sides, by a cylinder or a truncated cone, is defined in the “FOUND” section of the *.lag file. If the foundation is defined by a series of sides, the normal is given by the product of vectors $\vec{12}$ and $\vec{13}$ built on the nodes of the foundation $\vec{n}=\vec{12} \wedge\vec{13}$ of each side. This normal must be directed inwards the foundation.
If the foundation is cylindrical, it is represented by 3 nodes. The first 2 nodes represent the limits of the cylinder axis. The last node has coordinates $(R, \phi, 0)$, where $\phi$ represents the rotation of the cylinder ($\phi=0$ initially).
If the foundation is a truncated condeit is also represented by 3 nodes. The first 2 nodes represent the limits of the truncated cone axis. The last has coordinates $(R_1, R_2, \phi)$ where $R_1$ and $R_2$ are the radius at node 1 and 2, and $\phi$ represents the rotation of the truncated cone ($\phi=0$ initially).
This element can only be used with law COU2DC/COU3DC. It induces friction and thermal exchanges by radiation-convection or with thermal resistance. It can work in thermal, mechanical, or thermo-mechanical analysis.
Implemented by: J.P. Radu, 1989
Files
Prepro: CFI3DA.F
Lagamine: CFI3DB.F
Input file
| Title (A5) | |
|---|---|
| TITLE | “CFI3D” in the first 5 columns |
| Control data (2I5) | |
| NELEM | Number of elements |
| INSIG | = 0 no initial stresses |
| = 1 → initial stresses | |
| Initial stresses - only if INSIG = 1 (6G10.0) | |
| The pressure varies as: $PRESS = PRES0 + (Z*DPRES)$ Tau varies as: $TAUn = TAUn0+(Z*DTAUn)$ |
|
| PRES0 | Pressure of the contact at the axis origin |
| DPRES | Coefficient of variation of the pressure along Y (= 0 → constant pressure) |
| TAU10 | TAU along direction 1 at the axis origin |
| DTAU1 | Coefficient of variation of TAU1 along Z (= 0 → constant TAU1) |
| TAU20 | TAU along direction 2 at the axis origin |
| DTAU2 | Coefficient of variation of TAU2 along Z (= 0 → constant TAU2) |
| Definition of elements | |
| (5I5) | |
| NINTE | Number of integration points (1, 4, or 9) |
| LMATE | Material law |
| IFOUN | Number of the foundation or tool If the number of the foundation is equal to 0, the thermal flow between the boundary and the environment, without any mechanical mechanical contact with a foundation |
| 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. |
|
| 4 → Coupled solid/foundation piloted in displacement contact (only if pilot node) Only one contact element defined on the structure. Corresponds to the case where IRIGF = 2, but with a reduction of the size of LM and AK and without any necessity to repeat the calculation of MBAND and NHICO (see ISTRA(4)) The computation method of AK with perturbation is adapted to the notion of piloted foundation |
|
| 5 → Coupled solid/foundation piloted in rotation contact (only if pilot node) Only one contact element defined on the structure. Corresponds to the case where IRIGF = 2, but with a reduction of the size of LM and AK and without any necessity to repeat the calculation of MBAND and NHICO (see ISTRA(4)) The computation method of AK with perturbation is adapted to the notion of piloted foundation |
|
| NELMC | Number of layers of contact element for this element = 1 (by default) ≠ 0 → use CF3MLB instead of CFI3D |
| Only if NELMC > 1 (4I5) - Repeated NELMC-1 times | |
| NINTE | Number of integration points (1, 4, or 9) |
| LMATE | Material law |
| IFOUN | Number of the foundation or tool |
| IRIGF | Type of contact |
| (8I5) | |
| NODES(8) | List of nodes |
Results
Stresses:
Pressure, tangent stress in direction 1, tangent stress in direction 2, thermal flow. The positive direction of $\tau$ is along $-\xi$, $-\eta$
Internal variables:
The first values are the ones relating to the law (for Coulomb law, this will be: plasticity indicator, dissipation, information on mechanical dissipation in thermal flow). The 2 last values correspond to the contact geometry. They are:
- The segment number of the foundation in contact
- The interpenetration distance