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SUCHA
| Element law | SUCHA - Type 19 |
| Constitutive law | LICHA - Colaw Nb.95 |
| Loading state | 3D (2D line elements not implemented) |
Description
SUCHA elements are 3D surface-type elements used to define the application of an evenly distributed pressure (i.e., stress) over a bidimensional surface. This is particularly useful when conducting creep test simulations, where the axial force is held constant over time.
How to initialize in GMSH
The physical group where the SUCHA elements are contained must be named as:
SUCHA01x123y-0.2e-3z1.55
where:
| SUCHA |
|---|
| Is the standard element type name |
| 01 |
| Is the number of the element type group; different SUCHA groups can be created as SUCHA01, SUCHA02, .. |
| x123y-0.2e-3z1.55 |
| Indicates a point (x,y,z) located inside the surface. The coordinates of the point are defined by the letters of the corresponding axes followed by the position in the axis. The numbers can be of any real type and of any length. This point is used to indicate the desired direction of the normal vectors across all SUCHA elements. The desired direction is obtained as The direction is later verified while writing the *.lag file, and the order of the nodes is modified if necessary, according to the user input. An example of the verification algorithm is provided in the Figure below. |
In the figure, the point $x_{0},y_{0},z_{0}$ introduced as SUCHA01X$x_{0}$Y$y_{0}$Z$z_{0}$ is used to obtain the user-defined normal unitary vector $\hat{u}$. Then:
- The default normal vector of the surface composed by the nodes ABCD is indicated by the normal unitary vector $\hat{n}$.
- The direction of the surface normal vector $(\hat{n})$ is then compared to that of the user-defined normal $(\hat{u})$. This is performed by comparing the norm of the addition $|\hat{n}+\hat{u}|$ and subtraction $|\hat{n}+(-\hat{u})|$ of both normal vectors. In the Figure:
- If Case 1: The default normal vector $\hat{n}$ indicates the desired direction. The nodes of SUCHA surfaces belonging to the analyzed group are written following the default ABCD node order.
- If Case 2: The default normal vector $\hat{n}$ indicates the wrong direction. This is fixed during the *.lag file writing process by changing the order of the nodes belonging to the analyzed SUCHA group; from ABCD to ADCB.
